With Manufacturer's Scan Tool
Motronic Engine Control Module (ECM) Power Supply Relay -J271-, Checking
Special tools and equipment
- V.A.G 1526 A
- V.A.G 1594 A
- V.A.G 1598/31
NOTE: The Motronic Engine Control Module (ECM) Power Supply Relay -J271- supplies ignition coils with output stages as well as ECM on Pin 121 with power.
Test sequence
- Remove engine cover -arrows-.
- Disconnect 4-pin connector -1- from ignition coil -2-.
- Connect multimeter as follows to measure voltage.
Connector terminal Measure to
1 Engine ground (GND)
- Switch ignition on.
- Specified value: approx. battery voltage (B+)
If specified value is not obtained:
- Switch ignition off.
- Disconnect power supply relay -1- under cover on left bulkhead.
NOTE: To remove protective cover on vehicles with relay carrier on bulkhead, disconnect and lower. If necessary, disconnect connector from mass air flow sensor.
- Check for open circuit in following wiring according to wiring diagram:
Relay carrier under cover on left Connection of ignition coils.
bulkhead, terminal terminal
2 1
- Repair open circuit, if necessary.
If wiring is OK:
- Check voltage supply of Motronic Engine Control Module (ECM) Power Supply Relay -J271-.
- Check activation of Motronic Engine Control Module (ECM) Power Supply Relay -J271-.
Checking power supply
- Switch ignition off.
- Disconnect power supply relay -1- under cover on left bulkhead.
NOTE: To remove protective cover on vehicles with relay carrier on bulkhead, disconnect and lower. If necessary, disconnect connector from mass air flow sensor.
- To measure voltage connect multimeter as follows:
Relay carrier under cover on left Measure to
bulkhead, terminal
1 Engine ground (GND)
3 Engine ground (GND)
- Specified value: approx. battery voltage (B+)
If specified value is not obtained:
- Perform following tests, specified by below:
- Check Fuse S10 (in fuse carrier, location 10).
- Check Fuse S134 (110A) in main fuse box/battery.
- Check wiring from Battery + (30) through fuses S134 and S10 to Motronic Engine Control Module (ECM) Power Supply Relay -J271- (under cover on left bulkhead).
Checking activation
- Switch ignition off.
- Disconnect power supply relay -1- under cover on left bulkhead.
NOTE: To remove protective cover on vehicles with relay carrier on bulkhead, disconnect and lower. If necessary, disconnect connector from mass air flow sensor.
- To measure voltage connect multimeter as follows:
Relay carrier under cover on left Measure to
bulkhead, terminal
5 Battery voltage (B+)
- Switch ignition on.
- Specified value: approx. battery voltage (B+)
If specified value is not obtained:
- Switch ignition off.
- Connect test box V.A.G 1598/31 to wiring harness for ECM; do not connect ECM. Electrical Testing Using VAG1598/31 Test Box
- Check following wire connections for open circuit and short circuit to Ground (GND) and B+:
Relay carrier under cover on left VAG 1598/31 Test Box
bulkhead, terminal Socket
5 21
- Repair open circuit, if necessary.
If no malfunction is detected:
- Replace the Motronic Engine Control Module (ECM) Power Supply Relay -J271-.