DTC 134

DL. DTC 1-3-4
1-3-4 Faulty load signal

Principle of operation

The engine load signal (TQ) supplies information on the torque developed by the engine. The signal indicates if the engine is idling or if the fuel cut-out function is active, and also indicates the engine speed.

Fault description

TCM receives no engine load signal (TQ) although speed sensor on transmission indicates that engine is delivering power. Troubleshooting should indicate if fault is due to faulty Motronic 1.8 ECM wiring, faulty signal from Motronic 1.8 or faulty TCM.





Circuit description

The circuit consists of the TCM, Motronic 1.8 ECM and associated wiring and connectors.





1
Checking load signal lead

- Switch off ignition.
- Remove fuse 24.
- Connect break-out box to AW 30-40/30-43 wiring.
- Disconnect Motronic 1.8 ECM connector.

Connect ohmmeter between # 46 (TO) on break-out box and Motronic 1.8 terminal 3.9.

- Instrument should indicate approx. 0 Ohm if lead is intact (no open-circuit).

Connect ohmmeter between # 46 (TQ) and # 12 (SG) on break-out box.

- Instrument should indicate Infinite resistance if lead is not shorted to ground.





2
Checking ground terminal (signal ground)

Connect ohmmeter between # 12 (SG) on break-out box and Motronic 1.8 terminal 1.9.

- Instrument should indicate approx. 0 Ohm if lead is intact (no open-circuit).





3
Checking transmission ground terminal (power ground)

- Connect break-out box between TCM and wiring.
- Reconnect Motronic 1.8 connector.
- Install fuse 24.
- Switch on ignition.

Connect voltmeter across # 11 (PG) and # 12 (SG).

- Instrument should indicate less than 0.7 volt, otherwise ground connections are poor. In this case, check leads and connections to ground terminals as described in Testing and Inspection. Component Tests and General Diagnostics

Check that no non-factory-fitted system is connected to signal ground. Systems of this type may cause interference.

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