DTC 223

EF. DTC 2-2-3
2-2-3 TP sensor signal too low

Principle of operation

Supplied by a sensor mounted at the throttle, via the Motronic 1.8 ECM, the TP sensor signal describes the degree of throttle opening. The signal can vary from 0.2 to 4.8 V, increasing with the opening. The value should be between 4.0 and 4.8 V at WOT and between 0.2 and 1.0 V at CTP. Among other functions, the TCM uses the signal to control the gearshifting points and transmission line pressure.

Fault description

The TCM input signal is too low (below 0.2 V). The lock-up function is inoperable and gearshifting is 'hard'. The TCM emergency program is activated and the MIL lights. Troubleshooting should indicate if the fault is in the TP sensor, the Motronic 1.8 ECM, the TCM or the leads between the modules (short-circuit to ground, loose lead).





Circuit description

The circuit consists of the TCM, six connectors, the TP sensor and the Motronic 1.8 ECM.





1
Display Motronic 1.8 DTCs In test mode 1

Using test mode 1, check whether DTC have been stored in Motronic 1.8 diagnostics. How to display codes for Motronic 1.8 can be found in Computers and Control Systems, Testing and Inspection. Testing and Inspection

- If DTC have been recorded, carry out troubleshooting as described in Computers and Control Systems, Testing and Inspection. Testing and Inspection

- If no DTC has been recorded, proceed to step 2.





2
Measuring TP sensor signal from Motronic 1.8 ECM to AW 30-4O/AW 30-43 TCM

- Switch off ignition.
- Connect break-out box between AW 30-40/AW 30-43 TCM and wiring.
- Switch on ignition.

Connect voltmeter across # 31 (VTH) and # 12 (SG) on break-out box.

- Instrument should indicate low voltage (at least 0.2 V) at CTP and high voltage (max. 4.8 V) at WOT.

Proceed to step 3.

3
Checking ground terminal connections on transmission

- Switch on ignition.

Connect voltmeter across # 12 (SG) and ground terminal at A-post. Note reading for comparison with reading in step 5.

- Instrument should indicate less than 0.7 V if TCM is connected securely to ground terminal.
If readings in this and previous measurement are correct, proceed to step 5 to check Motronic 1.8 ground connection.

Otherwise, proceed to step 4.





4
Measuring TP sensor signal from Motronic 1.8 ECM

- Switch off ignition.
- Remove fuse 24.
- Connect break-out box to Motronic 1.8 ECM.
- Install fuse 24.
- Switch on ignition.

Connect voltmeter across # 49 (VTH) and # 19 (SG) on break-out box.

Instrument should indicate low voltage (at least 0.2 V) at CTP and high voltage (max. 4.8 V) at WOT.

Proceed to step 5.

- If instrument indicates other value, carry out troubleshooting for DTC in Computers and Control Systems, Testing and Inspection. Testing and Inspection

5
Check Motronic 1.8 ECM ground terminal connection

- Switch on ignition.

Connect voltmeter across # 19 (SG) and ground terminal at A-post.

- Instrument should indicate less than 0.7 V if ECM is connected securely to ground terminal.

Conclusions

- If difference between voltage measured in steps 3 and 5 exceeds 0.1 V, ground terminal connections are poor. Check and rectify connections.

Return to Testing and Inspection. Diagnostic Procedures

- If instrument indicates other value, carry out troubleshooting for DTC in Computers and Control Systems, Testing and Inspection. Testing and Inspection