Motronic ECM Power Supply Relay-J271, checking

Motronic Engine Control Module (ECM) Power Supply Relay-J271, checking

The Engine Control Module (ECM), ignition coils and valves for camshaft adjustment are powered via the ECM power supply relay, -J271.

The ECM power supply relay -J271 will be activated with the ignition on.

Test conditions
- Battery voltage OK

Checking activation of the ECM power supply relay







NOTE: The ECM power supply relay is located in the electronics box in the front passenger's footwell, (relay panel, relay position 2).


- Switch ignition off.
- Connect VAG1598/31 test box to wiring harness for engine control module. Do not connect to the engine control module itself. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG1598/31 Test Box" Testing and Inspection

Specification: The ECM power supply relay should be activated.

If the relay is now activated but not while switching ignition on:
- Replace Engine Control Module (ECM)
- If the relay does not activate:
- Check voltage supply for the ECM power supply relay







Checking voltage supply for ECM power supply relay
- Check fuse for ECM power supply relay -J271.

If the fuse is not faulty:
- Remove ECM power supply relay from the relay panel (relay position 2).







- Connect hand-held multimeter (voltage measurement range) between Ground (GND) and terminal 4 on relay panel.

Specification: approx battery voltage

If the specification is not obtained:
- Check wiring

If the specification is obtained:
- Test for open circuit and short to B+ or Ground (GND) in the following wiring connection:

Micro central electrics VAG1598/31 test
in passenger's footwell box
(right), relay position 2

terminal Socket
9 23

- Repair any open/short circuit as necessary.

If no malfunction is detected in the wire:
- Replace ECM Power Supply Relay -J271.
- Display readiness code. The readiness code must be regenerated if the DTC memory was erased.
Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Readiness Code" Testing and Inspection
Refer to "Monitors, Trips and/or Drive Cycle (Readiness Codes)/Generating Readiness Code" Testing and Inspection

Activating Cruise Control System (CCS)
- Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01". When doing this the ignition must be switched on. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAS5051 or VAG1551" Testing and Inspection

Indicated on display


Rapid data transfer HELP
Select function XX


- Press button -1- twice to select "Log-in procedure" function and confirm entry with -Q- button.

Indicated on display


Log-in procedure HELP
Input code number XXXXX


- Input code number 11463 and confirm entry with Q key.
- Select (for measure of control) "address word" 01 to select control module for engine control module.

Indicated on display


4D0907558.. 4.2L V8/5V G D.. ->
Coding 06753 WSC 06388


Specified value: "G"