Engine Speed Dips When Gear Is Engauged (Automatics)

FAULT TRACING INFORMATION

Conditions
^ DTCs absent
^ Engine warm.
^ Fault permanent.

Fault Sources
^ Break in signal lead from AW 30-43.
^ Signal lead short circuited to ground.
^ Contact resistance in contacts.
^ Defective gear selector or Idle Air Control (IAC) Valve.

TESTING PROCEDURE





Check Signal From AW 30-43
^ START engine and allow to idle.
^ Move gear selector to N and note what the Scan Tool (ST) reads for gear position.
^ Move gear selector to D and note what the ST reads for gear position.





^ Compare values in table for continuous fault tracing.





Check IAC Valve Connector
^ Clean and grease ECMs and IAC valve connectors.
^ Check whether engine still slows.

If engine does not slow:
- Source of fault is bad contact in IAC valve connector.
If engine still slows:
- Test with a new IAC valve,





Check Signal Lead, Constant Park / Neutral
^ Ignition OFF.
^ Remove fuse 1 (11B/1) in central relay unit.
^ Disconnect AW module.
^ Connect breakout box with adapter P/N 9813194 to wiring.
^ Replace fuse 1.
^ AW-ECM disconnected.
^ Ignition ON.





^ Connect a voltmeter between #15 on TCM connectors (position 45 in breakout box) and #11 (position 11 in breakout box).

Voltmeter should read over 5 Volts.

If value OK:
- Check signal from gear selector to ECM.
If value differs:
- Check lead between Motronic module connector #42 and AW-ECM 16-pin connector #15 for break.





Check Signal Lead, Constant R/D/3/L
^ Ignition OFF.
^ Remove fuse 1 (11B/1) in central relay unit.
^ Disconnect AW-ECM.
^ Replace fuse 1.
^ Ignition ON.
^ Check what ST reads for gear position.

If ST continues to read R/D/2/1 or R/D/3/L.
- Check lead between Motronic module connector #42 and AW-ECM 16-pin connector #15 for short circuit to ground.
If ST reads P/N.
- Check signal from gear selector to TCM.