Motronic Engine Control Module Power Supply Relay J271, Checking

Motronic Engine Control Module Power Supply Relay J271, Checking

Special tools, testers and auxiliary items required
- Multimeter
- wiring diagrams

NOTE: The manufacturers test box Adapter Cable (121-point) VAG1598/31 is available for purchase or rental.

Test requirements
- The fuse for the engine electronics OK.
- The Ground (GND) connections at the engine and transmission OK.
- The battery voltage at least 12.5 V.
- The generator OK.
- The ignition is switched off.

Test procedure
- Perform a preliminary check to verify the customers complaint. Preliminary Check

Start diagnosis

Test sequence
- Switch the ignition on.
- Using the Multimeter, check the following wiring connections for voltage.

Motronic Engine Control Measure to
Module (ECM) J623 electrical
connector T94 terminal or
test box socket
4 Battery Positive (B+)
69 Engine Ground (GND)

Specified value: 12.5. battery voltage.

- Switch the ignition off.

If the specified values are not obtained:
- Using the Multimeter, check the wiring connections for an open circuit.

Specified value: Wire resistance max 1.5 Ohms.
- If necessary, repair the wiring connection.
- Erase the DTC memory. Diagnostic Modes 01 - 09.
- Perform a road test to verify repair.

If the DTC does not return:
Repair complete, Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes
- End diagnosis.

If the DTC does return and no malfunction is detected in the wiring and the voltage supply was OK:
- Replace the Motronic Engine Control Module (ECM) J623.
- Assembly is performed in the reverse of the removal.

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:

1. Check the DTC memory. Diagnostic Modes 01 - 09
2. If necessary, erase the DTC memory. Diagnostic Modes 01 - 09
3. If the DTC memory was erased, generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

End of Diagnosis