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Checking disconnection of full-loadenrichment

Symptom: Diagnostic trouble codes generated in the MOTRONIC.

Checking disconnection of full-load enrichment


Fault symptom

Diagnostic trouble codes generated in the MOTRONIC.



Diagnostic procedure


1. Study what is described in "Disconnection of full-load enrichment".

2. If other diagnostic trouble codes have been generated in the MOTRONIC, or if any of the trouble codes B1406, B1407 or B1408 have been generated in the TCS, deal with them first. If no trouble codes have been generated, continue with point 3.



Drive the car on the road and check whether any trouble codes are generated afresh in the MOTRONIC. If they are, proceed as follows:

3. With the ignition switched off, connect a BOB to the TCS. While the engine is still hot and switched off, and with the ignition switch in the Drive position, check whether a 100 Hz PWM signal (0.2-0.82 ms (+), 2-8.2 %% (+), 0.25-1.0 V) is present on pin 11.


If it is not, the fault is in the MOTRONIC system.

If the signal is OK, continue with point 4.

4. With the engine still hot and switched off, and with the ignition switch in the Drive position, check whether a 31 Hz PWM signal is present on pin 21. The signal should be about 6 V.


If the signal is OK, check the cable to pin 38 of the MOTRONIC control module for continuity.

If the signal is not OK, check the cable to pin 38 of the MOTRONIC control module for shorting to ground.

5. If the lead connected to pin 38 of the MOTRONIC control module is OK and no signal is received although it is present on pin 21 of the TCS control module, see "Before replacing a control module" for further meausres.