Thunderbolt V Ignition System
Contents
1. TO ENGINE TO DISTRIBUTOR HARNESS A p ee 2 T a gt 2 2 S D lt 2 WO I 5 2 lt 7 0 E C 20 See NOTE 1 5 i T 2 2 Z w 1 Tou 2 00 44 T xt f 4 RHO KNOCK 5 CONTROL MODULE IGNITION CONTROL MODULE 18 S 75069 NOTE 1 Alpha Models Are Equipped With A Shift Cut Out Switch Brav2. Spark Plugs Tammy Lubricants Sealers and Adhesives DESCRIPTION PART NUMBER Loctite 271 Obtain Locally Thermalconductive Grease Coil Specifications Coil Part Number 392 7803A4 Primary Resistance 60 80 Ohms Secondary Resistance 9 400 11 700 Ohms faa a Index FU EDEL 90 823226 1 996 IGNITION SYSTEM 4B 1 Exploded View for Thunderbolt IV Distributor For V 6 Engines Distributor Cap Vent Gasket Rotor Sensor Wheel Screw 3 E Clip Shaft Screw 2 0 Lockwasher 2 4B 2 IGNITION SYSTEM 72058 Sensor Ignition Amplifier Screw 2 Distributor Housing Lockwasher Nut Gasket Washer Gear Roll Pin 90 823226 1 996 MCM V 6 262 CID 4 3L with Thunderbolt IV Module Part Number 805361 T 1 Identification Mark V6 14 Module Advance 14 Initial Timing 8 BTDC Total Advance 22 35 30 lt 2 25 lt lt 20 gt n E 2 15 10 5 500 1000 1500 2000 2500 3000 3500 ENGINE R P M Index 90 823226 1 996 4000 4500 5000 MIN 70808 7 IGNITION SYSTEM 4B 3
3. 4B 11 General Description 4B 12 Idle Speed Spark Control 4B 12 Acceleration Spark Advance 4B 12 Mean Best Timing MBT Spark Advance 4B 12 Over Speed 0 0 4B 12 Knock Retard Spark Control 4B 12 Thunderbolt V Spark Control Graph 4B 13 Circuit Description 4B 14 Ignition Control Module 4B 14 Knock Control Module 4B 14 Ignition Control System Timing Lead 48 14 Ignition System Wiring Diagram 4B 15 Timing and Idle Adjustment Procedures For Thunderbolt V Ignition 4B 16 Setting Base Ignition Timing 4B 16 Adjusting Idle Mixture 4B 16 Adjusting Engine Idle Speed 4B 16 Troubleshooting Thunderbolt V Ignition 4B 17 Ignition Control Module Coil Distributor 4B 17 Knock Control Module 4B 18 Spark 95 4B 19 Spark Plug Wires 4B 20 Index Thunderbolt IV Ignition System a Ignition Module 72722 Special Tools MERCURY MARINE SPECIAL TOOLS DESCRIPTION PART NUMBER 91 99379 91 99750 91 63209 92 41669 92 25711 2 Timing Light Multi Meter DVA Torch Lamp Insulating Compound Quicksilver Liquid Neoprene Torque Specifications 598 656 95 5
4. The locating key will appear as a clean edged 1 8 in 3 mm wide sloped ramp at the bottom of the splined hole 72980 Locating Key Screws Hex Head Sensor Wheel Locating Pin IGNITION SYSTEM 4B 5 there is any doubt if sensor wheel is located properly lay sensor wheel on top of the figure above with sensor fingers facing up toward you Line up three screw holes and locating pin hole on sensor wheel with the figure If wheel is in dexed properly all the fingers on wheel will line up with those in the figure there are pieces of material shaved off the key or if it appears to have been damaged by being forced down while misaligned with slot in distribu tor shaft the rotor must be replaced Check rotor for burned or corroded center con tact Check rotor for cracks and carbon tracks using magneto analyzer and instructions supplied with analyzer rotor is damaged replace rotor by removing three hex bolts and separating sensor wheel from rotor Reinstall sensor wheel to new rotor making sure locating pin on rotor is installed in locating hole in sensor wheel Tighten three hex bolts se Bend carbon brush tang upward slightly until a distance of 1 4 in 6 4 mm is obtained between rotor and tang 72979 1 4 in 6 5 mm 10 Put 2 drops of Loctite 271 or Quicksilver Loctite Type A into the rotor so it lands on the locating key Index 4B 6 IGNITION SYSTEM
5. 11 12 13 14 15 Put 2 drops of Loctite 271 in keyway on upper portion of distributor shaft Immediately install rotor assembly onto distribu tor shaft Make sure rotor locating key is aligned with keyway in distributor shaft before pressing rotor all the way down on the shaft until it stops with the palm of your hand Let Loctite cure over night with distributor in inverted position The rotor should fit very tight It may be necessary to heat rotor with torch lamp to properly install It is important not to let any Loctite run down distrib utor shaft Loctite could get into top distributor housing bushing Reinstall distributor cap on distributor Install spark plug wires if removed Refer to Spark Plug Wires in this section Sensor 1 2 Remove rotor and sensor wheel Remove two screws that hold sensor into distrib utor housing Remove sensor from housing 72732 a Mounting Screws b Sensor Assembly 90 823226 1 996 4 Use magnifying glass and light to inspect the 3 Adjust spark plug gaps with a round feeler gauge two metal jumper leads for cracks If a crack is Refer to Specifications for proper spark plug found in either metal jumper lead install a new gap sensor 72733 a Jumper Leads CAUTION Do not use any type of silicone sealer on the in side of the distributor Most silicone sealers give off an acidic vapor during the curin
6. sensor wheel and rotor as pre viously outlined Install distributor as outlined in Distributor Instal lation Index 90 823226 1 996 Distributor Installation Engine Not Disturbed 1 2 Install new gasket on distributor housing Turn rotor approximately 1 8 turn in a counter clockwise direction past mark previously scratched on distributor housing Work distributor down into position in engine block with distributor positioned as noted during removal lt may be necessary to move rotor slightly to start gear into mesh with camshaft gear but rotor should line up with the mark when distributor is down in place Distributor shaft must enter oil pump shaft for complete installation Replace and tighten distributor hold down bolt and clamp Connect leads Also install spark plug and coil secondary wires if removed Install cap Refer to Spark Plug Wires and in Stall wires Plug wiring harness into ignition amplifier on dis tributor housing Time ignition as outlined under Ignition Timing IGNITION SYSTEM 4B 9 Engine Disturbed A CAUTION If timing chain has been aligned as outlined Section 3A Timing Chain and Sprocket the No 4 cylinder is on compression TDC and the distributor MUST BE installed with the rotor posi tioned at the No 4 post on the distributor cap Electrical timing on No 1 spark plug remains the same as outlined following Te Locate No 1
7. high or too low a false signal can also be sent TESTING KNOCK MODULE AND SENSOR NOTE A digital volt ohmmeter DVOM and an un powered test light low power test light or less are needed to conduct the following test Avoid fire or explosion Ensure that engine compartment is well ventilated and gasoline va pors are not present when performing electrical tests inside the engine compartment Sparks generated by electrical tests could ignite gaso line vapors causing fire or explosion 1 Start engine and warm it up to normal operating temperature 2 Connect the positive lead from the DVOM to the PURPLE WHITE timing terminal that comes from the engine harness see previous wiring dia gram Connect the negative lead from the DVOM to a good engine ground With the en gine running there should be 8 10 volts on this circuit If voltage is not present check to ensure that there is 12 volts to the knock module PUR PLE wire Terminal 3 Advance the throttle to approximately 1500 RPM Disconnect the harness connector BLUE wire from the knock sensor Connect the unpowered test light to a positive 12 volt source To simu late an AC voltage rapidly tap the knock sensor harness terminal with the test light If knock mod ule and wiring is functioning properly you should see a voltage drop onthe DVOM a voltage drop is not seen check the BLUE wire from the sensor to the knock modul
8. piston in firing position by either of two methods described below a Remove No 1 spark plug and with finger on plug hole crank engine until compression is felt in No 1 cylinder Continue cranking until pointer lines up with timing mark on crank shaft pulley or Remove rocker cover and crank engine until No 1 intake valve closes continuing to crank slowly until pointer lines up with timing mark on crankshaft pulley Position distributor to opening in block in normal installed attitude Position rotor to point toward No 1 cylinder on cap with distributor housing held in installed atti tude then turn rotor counterclockwise approxi mately 1 8 turn more and push distributor down to engage camshaft It may be necessary to ro tate rotor slightly until camshaft engagement is felt While pressing down firmly on distributor hous ing engage starter a few times to make sure oil pump shaft is engaged Install hold down clamp and bolt and snug up bolt Place distributor cap in position and check that rotor lines up with terminal for No 1 spark plug Install cap Refer to High Tension Leads and install wires Refer to Specifications for firing order Time ignition as outlined under Ignition Timing Index 4B 10 IGNITION SYSTEM Ignition Timing 1 Connect timing light to No 1 spark plug Connect power supply leads on light to 12 volt battery Re fer to Specifications for cylinder
9. temperature Refer to the Operation and Mainte nance Manual for the correct idle speed 1 Disconnect the throttle cable from carburetor IMPORTANT In order to properly set idle speed the ignition module MUST BE locked in the Base Timing Mode This is necessary because of the Idle Speed Control feature that exists in the ignition module See information on the previous pages about this feature 2 Connect a shop tachometer to engine Using a jumper wire connect the ignition system timing lead 13 PUR WHT wire to a good en gine ground This locks the ignition module into the Base Timing Mode 4 Start engine and allow it to reach normal operat ing temperature 5 Adjust idle soeed to recommended RPM Stop engine Readjust cable barrel and reinstall the throttle IMPORTANT Be sure to disconnect the jumper wire from the ignition system test terminal before attempting to resume normal operations If the jumper wire is left in place the ignition module will operate in the Base Timing Mode This means that the additional timing advance fea tures would not be functioning 7 Remove the jumper wire from the timing terminal 90 823226 1 996 Troubleshooting Thunderbolt V Ignition Ignition Control Module Coil Distributor Check to ensure that tachometer GRY lead is not shorted to ground at the tachometer or within the harness Check all Terminal Connections at Di
10. ELECTRICAL SYSTEMS Index Table of Contents Page Thunderbolt IV Ignition System 4B 1 Special 4B 1 Torque Specifications 4B 1 Lubricants Sealers and Adhesives 4B 1 Coil Specifications 4B 1 Exploded View for Thunderbolt IV Distributor For V 6 Engines 4B 2 MCM V 6 262 CID 4 3L with Thunderbolt IV 4B 3 Replacement Parts Warning 4B 4 Spark 5 4 Firing 4 Distributor Advance Curves 4B 4 Repair 4B 4 Precautions 4B 4 Distributor 4 5 Rotor Sensor Wheel 4B 5 svcd hare hae E 6 Spark 5 7 Ignition Module 4B 8 Spark Plug Wires 4B 8 Distributor Repair 4B 8 Removal 8 Disassembly 8 Reassembly 9 Distributor Installation 4B 9 Engine Not Disturbed 4B 9 Engine Disturbed 4B 10 Ignition Timing 4B 10 Thunderbolt V Ignition System 4B 11 Identification
11. Mark distributor housing in reference to engine block Remove bolt and hold down clamp and remove distributor To simplify distributor installation do not turn crankshaft when distributor is removed from en gine Disassembly 1 Remove rotor sensor wheel and sensor as pre viously outlined Remove roll pin washer and driven gear from distributor shaft Check for side play between shaft and distributor housing bushings Maximum side play is 002 in 0 05 mm Remove shaft from housing and check shaft for being bent with a dial indicator and V blocks Maximum runout is 002 in 0 5 mm 90 823226 1 996 Reassembly 1 Lubricate shaft with engine oil Install E clip if re moved on shaft in housing Install washer on shaft Install original gear slide onto shaft and install roll pin Hole may be offset and gear will only fit in one di rection If installing new gear the gear will come drilled on one side Slide gear onto shaft align hole in gear with hole in shaft Using these holes as guides drill through other side of gear with a 3 16 in carbide tripped drill lf anew gear has only a dimple you will have to drill through one side of the gear before you slide gear onto shaft In most cases it is recommended to have a machine shop complete the drilling op eration for new gear installation 72735 Drill Press 3 16 In Carbide Tip Drill V Block New Gear Install sensor
12. Replacement Parts Warning Electrical ignition and fuel system components on your MerCruiser are designed and manufac tured to comply with U S Coast Guard Rules and Regulations to minimize risks of fire and explo sion Use of replacement electrical ignition or fuel system components which do not comply with these rules and regulations could result in a fire or explosion hazard and should be avoided Spark Plugs Gen Spark Plug 035 In 045 In Gap 0 9 mm 1 1 mm AC MR43LTS Spark Plug NGK BR6FS NGK BPR6EFS Type Champion Champion RV8C RS12YC AC MR438T Firing Order Firing Order 1 6 5 4 3 2 72976 Index 4B 4 IGNITION SYSTEM Distributor Advance Curves 1 Distributor advance curve charts do not include the initial engine timing Basic initial timing must be added to chart for total advance curve 2 The spark advance is controlled by the ignition module Repair Precautions When performing the following procedure be sure to observe the following e Be sure that engine compartment is well ventilated and that no gasoline vapors are present to avoid the possibility of fire e Be sure to keep hands feet and clothing clear of moving parts 9 Do touch or disconnect any ignition system parts while engine 15 running 9 Do not reverse battery cable connections System is negative ground 9 Do not disconnect battery cables while en gine is running 90 823226 1 996 D
13. T The graph below shows the typical advance ranges for a Thunderbolt V ignition control module The numbers plotted on the graph are not representative of any particular model It is only pres ented to provide an understanding of how the system functions TOTAL SPARK ADVANCE MINUS INITIAL TIMING 0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000 ENGINE R P M Base Timing Advance Curve Idle Speed Advance Range Knock Retard Range Acceleration Advance Range S MBT Advance Range Index FU EDEL 90 823226 1 996 IGNITION SYSTEM 4B 13 Circuit Description Refer to the circuit wiring diagram on the following page for reference to this circuit description Ignition Control Module The ignition module receives its power thru the PURPLE wire 9 Ignition module ground is accomplished thru the BLACK wire 10 There is also a Case Ground wire 12 that is connected to one of the ignition module attaching SCrews The 12 volt signal from the ignition module to the distributor is carried thru the WHITE RED wire 8 to the distributor sensor and back to the ignition module thru the WHITE GREEN wire 7 The tachometer signal 15 carried to the instrument panel thru the GRAY wire 11 PURPLE WHITE wire 3 carries the signal from the knock control module to the ignition control module There are two BLACK wires 5 that
14. ck is present the Knock module will remove the 8 10 volt signal to the Ignition Control Module Knock Sensor System a Positive Lead 12 Volts b 8 10 Volts To Knock Sensor Knock Sensor It is extremely important that the correct knock mod ule and sensor be used for the engine application Using an incorrect knock module or sensor will result unrecognized spark knock and engine damage The Knock module terminal B is powered by 12 volts from the ignition switch If the 12 volt power source is not present the knock module cannot send an 8 10 volt signal to the ignition control module and a false constant spark retard will result Terminal of the knock module is the signal line from the knock sensor If this circuit opens or shorts to ground the knock module will never remove the 8 10 volt signal from terminal C to and no spark re tard will occur The ground circuit for the knock mod ule is connected to terminal D If the ground circuit opens the knock module will not be able to remove the 8 10 volt signal and spark knock cannot be con trolled IMPORTANT If Knock sensor wire is routed too close to secondary ignition wires the Knock module may see the interference as a knock sig nal resulting in false timing retard Index 4B 18 IGNITION SYSTEM IMPORTANT If there is abnormal mechanical en gine noise rattles or knocks they may give a false knock retard signal If fuel octane is too
15. dule will control ignition timing to maintain a calibrated idle speed This is accom plished by making small spark advance adjustments This feature is only active within a certain RPM range This range may be slightly different from one engine model to another The approximate range is 400 700 RPM Acceleration Spark Advance This feature is active during acceleration only When accelerating the ignition module may add more spark advance to the Base Spark Timing Curve The amount of spark advance added is totally de pendant on how fast RPM increases how fast the throttle is moved This feature is also active within a certain RPM range This range may be slightly differ ent from one engine model to another The approxi mate RPM range for this feature is 1200 4000 RPM Within this range the module can add approximately 10 degrees of spark advance to the base spark timing curve Mean Best Timing MBT Spark Advance During light load cruising the ignition module searches for the optimal ignition timing This is also accomplished by small changes to the spark ad vance At a given RPM the module will try to add a small amount of advance and wait to see if there is an RPM change If RPM increases it will try to in crease timing more The module will continue to ad vance timing until it no longer gets an increase in RPM Conversely if it senses an RPM drop it will start to retard some of the spark timing The approxi mat
16. e RPM range for this feature is 1200 4000 RPM Within this range the ignition module can add approximately 10 15 degrees of spark advance to the base spark timing curve Index 4B 12 IGNITION SYSTEM NOTE The Audio Warning System is also connected into the ignition module circuit If the audio warning system becomes activated by the closing of one of the audio warning system switches the MBT feature is deactivated Over Speed Control The ignition module will prevent the engine speed from exceeding a preset limit by stopping the spark This feature has an RPM range that varies from mod el to model The over speed limit for a particular en gine is set slightly higher than the top end of the RPM range for that model For example if the recom mended range is 4600 5000 RPM the over speed limit would be set at 5100 RPM When RPM reaches this limit spark is turned off until engine RPM drops down to a Reset RPM which would be approxi mately 4750 RPM for this example At this point Spark comes back on Knock Retard Spark Control The knock control feature helps provide protection from harmful detonation Knock control is handled by the Knock Control Module This module receives a signal from a sensor that is mounted on the engine block The knock control module works in conjunc tion with the ignition module to retard the timing if spark knock is present 90 823226 1 996 Thunderbolt V Spark Control Graph IMPORTAN
17. e for a short or open circuit If the circuit is functioning properly to this point the knock sensor may not be functioning Proceed to the following step 5 Reconnect the knock sensor harness connector to the sensor 6 While still watching the DVOM lightly and rapidly tap on the engine block near the knock sensor with a small hammer If the knock sensor is func tioning properly you should see the voltage de crease If a voltage drop is not seen the knock sensor is faulty 90 823226 1 996 INSTALLATION OF KNOCK SENSOR IMPORTANT If installing a new knock sensor be sure to replace it with an identical part Knock sensors are very sensitive and designed for each specific application IMPORTANT It is very important that the knock sensor be torqued to the exact specification In correct torque procedure will result in unsatis factory performance DO NOT use sealer on threads 1 Install Knock sensor in engine block Torque to 12 16 lb ft 16 3 21 7 N m a Knock Sensor 2 Connect electrical connector to knock sensor Index 90 823226 1 996 Spark Plugs 1 Inspect each plug individually for badly worn electrodes glazed broken or blistered porcelain and replace where necessary 2 Inspect each spark plug for make and heat range All plugs must be the same make and number and heat range Refer to Specifications for spark plug numbers 3 Adjust spark plug gaps with a round feeler gauge Re
18. fer to Specifications for proper spark plug gap 12134 Porcelain Insulator Insulator Cracks Often At This Point Shell Proper Gap Side Electrode Bend To Adjust Gap Center Electrode File When Adjusting Gap DO NOT Bend 4 Clean spark plug seating area Do not use gas kets on taper seat plugs Install soark plugs and torque to specifications Where used gasket must be fully compressed to complete heat trans fer and provide a gas tight seal in cylinder For this reason as well as the necessity of maintain ing correct plug gap correct torque 1 very impor tant during installation IMPORTANT Tapered seat spark plugs are not in terchangeable with non tapered with gasket spark plugs Spark Plug Wires Inspect spark plugs for damage 2 Check spark plugs for continuity using Multi Me ter DVA 91 99750 or similar 3 Replace any wires that are cracked cut or have damaged spark plug boots 4 Replace any wires that do not show continuity from end to end 5 Reinstall wires in proper order Observe the fol lowing IMPORTANT Proper positioning in spark plug wire supports is important to prevent cross fir ing IMPORTANT Before installing coil wire to coil apply approximately 1 2 oz of insulating com pound around top of coil lead tower Force nipple into coil and wipe off excess Make sure boot does not hydraulically back off the distributor ca
19. g stage of the sealer This acid can cause corrosion on the igni tion components 5 Install sensor into housing and install two retain ing screws 6 Install sensor wheel rotor and distributor cap Spark Plugs 1 Inspect each plug individually for badly worn electrodes glazed broken or blistered porcelain and replace where necessary 2 Inspect each spark plug for make and heat range All plugs must be the same make and number and heat range Refer to Specifications for spark plug numbers Index 90 823226 1 996 0 OW 72734 Porcelain Insulator Insulator Cracks Often Occur at This Point Shell Proper Gap Side Electrode Bend to Adjust Gap Center Electrode File when Adjusting Gap DO NOT BEND Clean spark plug seating area Do not use gas kets on taper seat plugs Install soark plugs and torque to specifications Where used gasket must be fully compressed to complete heat trans fer and provide a gas tight seal in cylinder For this reason as well as the necessity of maintain ing correct plug gap correct torque Is very impor tant during installation Tapered seat spark plugs are not interchange able with non tapered with gasket spark plugs IGNITION SYSTEM 4B 7 Ignition Module 1 Unplug wiring harness connector from ignition module mounted on distributor Remove stainless steel screws retaining ignition module to distributor body Remove mod
20. have bullet connectors This circuit is reserved for future options On current models the two BLACK wires must be connected for the system to function properly The TAN BLU wire 6 carries a signal from the Audio Warning circuit to the ignition module Index 4B 14 IGNITION SYSTEM Knock Control Module knock control module receives its power from the PURPLE wire 4 Knock module ground is accomplished thru the BLACK wire 2 PURPLE WHITE wire 3 carries the signal from the knock control module to the ignition control module 9 BLUE wire 1 carries the signal from the knock sensor to the knock module Ignition Control System Timing Lead The ignition control system has lead with bullet connector 11 that is connected into the PURPLE WHITE wire 3 This lead is used for performing the following tests and procedures Setting Base Ignition Timing Setting Engine Idle Speed Setting Idle Mixture Testing Knock Control Circuit This lead when connected to an engine ground locks the ignition control module into the Base Tim ing mode 90 823226 1 996 Ignition System Wiring Diagram
21. istributor Cap 3 Loosen four distributor cap retaining screws 4 Remove distributor cap 5 Cleancap with warm soap and water and blow off with compressed air 6 Check cap contact for excessive burning or cor rosion Check center contact for deterioration 7 Check cap for cracks or carbon tracks using mag neto analyzer 8 Check condition of distributor cap gasket Re place gasket if damaged or missing 9 If high tension leads are removed from cap refer to Spark Plug Wires in this section and the fol lowing illustrations for installation Wiring Alignment Notch 12978 a Vent Index 90 823226 1 996 Rotor Sensor Wheel 1 Remove distributor rotor sensor wheel assembly from distributor shaft Rotor and sensor wheel are secured to the shaft with Loctite Use two flat blade screwdrivers The screwdrivers are posi tioned opposite each other with the blade tips on the underside of the rotor and sensor wheel as sembly Make sure blade tips are toward distribu tor shaft until they come in contact with shaft A downward push on both screwdriver handles at the same time will pry off rotor sensor wheel as sembly The use of torch lamp will also aid in the removal of the rotor sensor wheel assembly Wear protective gloves when handling heated ro tor sensor wheel assembly to avoid severe burns With the rotor sensor wheel assembly removed inspect the locating key inside the rotor
22. numbering and location Connect tachometer to engine Start engine and run at normal idle speed 4 Aim timing light at timing tab located on timing 2 O gear cover and crankshaft torsional damper GM engine timing marks on tab are in 2 degree increments LH engines will have A Ad vance mark to the left of O Timing must be set on the A side of 0 Top Dead Cen ter 12872 Degree Marks Timing Mark Adjust timing by loosening distributor clamp and rotating distributor body as required until timing mark on damper or pulley lines up with the mark on tab specified in Specifications Tighten clamp and recheck location of timing mark Stop engine and remove timing light 90 823226 1 996 Thunderbolt V Ignition System Identification The Thunderbolt V ignition system uses the same distributor as the Thunderbolt IV system The Ignition Control Module and Knock Control Module are mounted with the ignition control module 13999 Ignition Control Module b Knock Control Module Index IGNITION SYSTEM 48 11 90 823226 1 996 General Description The Thunderbolt V ignition system has several spark control features that will be described following idle Speed Spark Control Acceleration Spark Advance Mean Best Timing Spark Advance Over Speed Control Rev Limiter Knock Retard Spark Control Idle Speed Spark Control The ignition mo
23. o Models Will Have Two BLACK Leads Connected Together NOTE 2 Some Wiring Harnesses Will Not Have The Bullet Connector In This Location Bravo Only Wiring Har ness Will Have A BLACK Wire Harness Used For Bravo And Alpha Will Have A WHITE GREEN Wire 1 Knock Sensor Wire 8 Distributor Wire 2 Ground Wire For Knock Module 9 Battery Positive Wire To Ignition Module Knock Module Signal Wire 10 Ground Wire For Ignition Module 4 Battery Positive Wire To Knock Module 11 Tachometer Wire 5 Ground For Future Options 12 Ignition Module Case Ground 6 Audio Warning System Wire 13 Timing Lead For Setting Timing and Other Tests 7 Distributor Wire index el 90 823226 1 996 IGNITION SYSTEM 4B 15 Timing and Idle Adjustment Procedures For Thunderbolt V Ignition Setting Base Ignition Timing 1 Connecttiming light to number 1 spark plug Con nect timing light power supply leads if applica ble to 12 volt source Connect a shop tachometer to engine Using jumper wire connect the ignition system timing lead 13 PUR WHT wire to a good en gine ground This locks the ignition module into the Base Timing Mode 4 Start engine and run at normal idle speed Allow engine to reach normal operating temperature 5 Aim timing light at timing tab located on the tim ing gear cover and crankshaft torsional damper 6 Adjust timing using the conventional method IMPORTANT Be s
24. p terminal Index 4B 20 IGNITION SYSTEM 90 82322
25. stributor Ignition Module and Ignition Coil Battery OK Distributor Clamping Screw Tight Check Engine With Key in RUN Position and Instrument Check for 12 Volts at Positive Wiring Harness Terminal on Ignition Coil Volts Battery Cables Key Switch Unplug WHT RED bullet connector from Distributor 0 Check for 12 volts Volts on lead coming from module Reconnect WHT RED bullet connectors Remove High Tension Lead from Distributor to Coil Insert a Spark Gap Tester from Coil Tower to Ground Disconnect Replace Ignition WHT GRN Lead from Distribu Sensor in tor Place Ignition Key in RUN at Coll Position Rapidly strike the Ter minal of the WHT GRN Lead that comes from module against Ground See IMPORTANT below Distributor No Spark at Coil at Coil Substitute a New Ignition Spark Install New Coil Repeat Above Test at Coil Ignition Coil No Spark at Coil Replace Ignition Module IMPORTANT The WHT GRN lead must be touched against ground 2 3 times per second to ornate a running engine Repeat this test several times to ensure that spark is present Index 90 823226 1 996 IGNITION SYSTEM 4B 17 Knock Control Module The Knock Control Module contains solid state cir which monitors the knock sensor s AC voltage signal and then supplies an 8 10 volt signal if no spark knock is present to the Ignition Control Mod ule If spark kno
26. ule Thermalconductive Grease 92 805701 must be applied to the back of the ignition module to con duct heat away from the module and to prevent corrosion Apply a thin coat of Thermalconductive Grease evenly across the back of the ignition module Install ignition module using the stainless steel screws Torque screws 10 10 15 in 1 1 Check that terminals of wiring harness connector are clean and free of corrosion Plug connector into ignition module Spark Plug Wires Inspect spark plug wires for damage Check spark plug wires for continuity Replace any wires that are cracked cut or have damaged spark plug boots Replace any wires that do not show continuity from end to end Reinstall spark plug wires in proper order Ob serve the following Proper positioning in spark plug wire supports is important to prevent cross firing Before installing coil wire to coil apply approxi mately 1 2 oz of insulating compound inside nip ple of coil wire Force nipple into coil and wipe off excess Make sure boot does not hydraulically back off the distributor cap terminal Index 4B 8 IGNITION SYSTEM Distributor Repair Removal 1 Unplug wiring harness from ignition amplifier on distributor housing Remove distributor cap Do not remove high ten sion leads unless necessary Crank engine over until timing marks line up and rotor is pointing toward No 1 cylinder on distribu tor
27. ure to disconnect the jumper wire from the ignition system test terminal before attempting to resume normal operations If the jumper wire is left in place the ignition module will operate in the Base Timing Mode This means that the additional timing advance fea tures would not function 7 Make sure that the distributor has been tight ened Remove the jumper wire from the timing terminal 8 Stop engine and remove timing light Adjusting Idle Mixture The procedure for adjusting carburetor idle mixture can be found in the appropriate engine service manu al This procedure also requires that the ignition mod ule be locked in the Base Timing IMPORTANT In order to properly set idle mixture the ignition module MUST BE locked in the Base Timing Mode This is necessary because of the Idle Speed Control feature that exists in the ignition module See information on the previous pages about this feature Index 4B 16 IGNITION SYSTEM 1 Using a jumper wire connect the ignition system timing lead 13 PUR WHT wire to a good en gine ground This locks the ignition module into the Base Timing Mode Adjust idle mixture following the procedure in the appropriate engine service manual 3 Remove the jumper wire from the timing terminal Adjusting Engine Idle Speed This procedure should be done with boat in the water drive unit in neutral and engine at normal operating
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