BMW 3 Series Service Manual
Contents
1. 2 Turn on A C or shift car into drive Idle should remain steady or increase slightly 3 If valve is not buzzing or if idle decreases in step 2 stop engine and disconnect harness connector from valve Check resistance of valve across its terminals See Fig 30 Test values are listed below NOTE If you suspect an intermittent fault lightly tap the valve while testing resistance Fig 30 Idle speed control valve terminal identification Idle Speed Control Valve Coil Resistance Values e M50 S50US engine Terminals 1 and2 00000 20 5 ohms Terminals 2and3 00008 20 5 ohms Terminals 1 and3 0 000 40 5 ohms 4 With valve harness connector disconnected check for battery voltage at red white wire in connector with igni tion turned on e if there is no voltage check wiring between connec tor and main relay terminal 87 See Electrical Wiring Diagrams NOTE The idle speed control valve receives positive bat tery voltage from the main relay 5 If voltage is present as described above check wiring between ECM and vaive If no wiring faults are found check ECM signal to valve BOSCH DME M3 1 AND M3 3 1 COMPONENT TESTS AND REPAIRS Version electronica licenciada a Hernan Fulco hfulco iplan com ar tel 54 11 4855 3088 Buenos Aires Argentina2. 130 20 FUEL INJECTION 0011603 Fig 29 Throttle position sensor terminal identification on M50 engine Table g Throttle Position Sensor Tests DME 3 1 3 3 1 Harness connector 3 and ground 5 VDC approx disconnected igni in harness tion on connector 1 and 3 at sen sor terminals Harness connector disconnected igni tion off 4 k ohms approx Throttle plate rotat ed from idle to full throttle position Variable from 1 4 k ohms approx with out interruption 1 and 2 at sen sor terminals NOTE On cars with traction control do not confuse the throttle position sensor on the main throttle body with the throt tle position switch on the secondary throttle body where applicable idle speed control valve testing Idle speed is maintained by the ECM through the idle speed control valve The idle contro function compensates for engine load and engine operating conditions Idle speed is adaptive through the ECM and no idle speed adjustments can be made Before testing the valve confirm that the throttle position sensor is working correctly NOTE e The tests given below are electrical checks only They gt do not check the mechanical operation of the valve If the valve is suspected of causing poor idle substitut ing a known good valve is the best way to check for a mechanical fault 1 With engine running check that idle speed control valve is buzzing
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