Checking Signal From the Transmission Control Module

Checking The Signal From The AW 50-42 Transmission Control Module
- Start the engine and idle it.
- Select scrolling values.
- Move gear selector lever to N and note Volvo Scan Tool (ST) gear position reading.
- Move gear selector lever to D and note Volvo Scan Tool gear position reading.
- Compare the readings in the table (see image) to continue fault-tracing.





Select A Suitable Alternative

Alternative 1:
^ Proceed to test step below.

Alternative 2:
^ Proceed to Checking The Signal Cable, Constant P/N section below.

Alternative 3:
^ Proceed to Checking The Signal Cable, Constant R/D/3/L section below.





Cleaning Idle Air Control Valve Connector
- Clean and grease engine control module (ECM) and idle air control (IAC) valve connectors.
- Check if engine speed still dips.
- Do the fault symptoms persist?

Yes:
^ Try a new idle air control valve.

No:
^ Operation done.





Checking The Signal Cable, Constant P/N
- Ignition off.
- Wait approx. 150 seconds.
- Disconnect the transmission control module (TCM).
- Connect the test box to the transmission control module wiring.
- Ignition on.
- Connect a voltmeter between # 29 (# A29) and # 44 (# B14) on the test box.
- The reading should be 7 - 9 Volts.

If reading is OK:
^ Check the signal from the gear selector to the transmission conrol module.

If value is higher:
^ Check cable between engine control module # B24 and transmission control module (# B14) for a short-circuit to supply voltage.

If value is lower:
^ Check cable between engine control module # B24 and transmission control module (# B14) for an open-circuit.





Checking The Signal Cable, Constant R/D/3/L
- Ignition off.
- Wait approx. 150 seconds.
- Disconnect the transmission control module.
- Connect the test box to the transmission control module wiring.
- Ignition on.
- Connect a voltmeter between # 29 (# A29) and # 44 (# B14) on the test box.
- The reading should be 7 - 9 Volts.

If reading is OK:
^ Check the signal from the gear selector to the transmission control module.

If value is lower:
^ Check cable between engine control module # B24 and transmission control module # B14 for a short-circuit to ground.