Checking power supply relay for Motronic system -J271 — AUDI
Checking power supply relay for Motronic system -J271 on Audi: factory workshop procedure for engines AKC, AMK, ANK, AQF.
Workshop procedure for AUDI — the factory write-up, straight from real workshop data.
📐 20 workshop diagrams for AKC
Real factory drawings for this job — timing marks, bolt locations and routing. Locked in the free view.
📋 Procedure
BAM
Special tools and workshop equipment required
V.A.G 1526 A
V.A.G 1594 A
V.A.G 1598/31
Note:
The power supply relay for Motronic -J271 supplies the ignition coils with output stages as well as the engine control unit on Pin 121 with voltage.
Test sequence
Remove engine cover-arrows-.
Unplug 4-pin connector -1- from one of the ignition coils -2-.
Connect multimeter as follows to measure voltage.
Connector / Contact · Measure to
1 · Engine earth
Switch the ignition on.
Specified value: approx. battery voltage
If specified value is not attained:
Switch ignition off.
Disconnect the power supply relay -arrow- under left cover at the bulkhead.
Note:
To remove the protective cover in vehicles with dome strut, detach and lower relay holder at the bulkhead. If necessary, unplug connectors from air mass meter.
Check for open circuit in the following wiring according to wiring diagram:
Relay carrier under left cover at the bulkhead / Contact · Connection of ignition coils. / / Contact
2 · 1
Rectify open circuit, if necessary.
If the wiring is OK:
Check the voltage supply of the power supply relay -J171 => Page
28-16
.
Check the actuation of the power supply relay -J271 => Page
28-18
.
Checking power supply
Switch ignition off.
Disconnect the power supply relay -arrow- under left cover at the bulkhead.
Note:
To remove the protective cover in vehicles with dome strut, detach and lower relay holder at the bulkhead. If necessary, unplug connectors from air mass meter.
Connect multimeter as follows to measure voltage.
Relay carrier under left cover at the bulkhead / Contact · Measure to /
1 · Engine earth
3 · Engine earth
Specified value: approx. battery voltage
If specified value is not attained:
Carry out the following tests (marked with dots):
Check fuse S10 (in fuse box, position 10).
Check fuse S134 (110 A) in main fuse box/battery.
Check wiring from battery + (terminal 30) via fuse S134 and fuse 10 to power supply relay for Motronic -J271 (under left cover at bulkhead) for open circuit.
=> Current Flow Diagrams, Electrical Fault-finding and Fitting Locations binder
Checking actuation
Switch ignition off.
Disconnect the power supply relay -arrow- under left cover at the bulkhead.
Note:
To remove the protective cover in vehicles with dome strut, detach and lower relay holder at the bulkhead. If necessary, unplug connectors from air mass meter.
Connect multimeter as follows to measure voltage.
Relay carrier under left cover at the bulkhead / Contact · Measure to /
5 · Battery positive
Switch the ignition on.
Specified value: approx. battery voltage
If specified value is not attained:
Switch ignition off.
Connect test box V.A.G 1598/31 to wiring harness for engine control unit; do not connect the engine control unit => Page
24-19
.
Check for open circuit and short to positive or earth in the following wiring connection:
Relay carrier under left cover at the bulkhead / Contact · Test box V.A.G 1598/31 / Socket
5 · 21
Rectify any open/short circuit as necessary.
If no fault is found:
Replace the power supply relay -J271.
TorqFix answers live for your specific car — tell it the engine code and it serves the matching sequence, torque figures and wiring for that exact variant.
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Who makes these pages, and how
TorqFix was built by a mechanic — after a 2,700 km drive with five roadside repairs that no diagnostic tool could explain.
The figures on this page come from manufacturer workshop documentation and are shown as they are. The page is assembled automatically from that data — it is not written by an AI. The AI works in the chat, where it answers for your specific car. It writes nothing here.
Variants of the same model differ. Cross-check torque against the factory manual for your engine before final tightening.
Seen a figure that does not match your manual? Write to us — we correct it and note when. support@torqfix.com
The story behind TorqFix →Workshop data on this page last updated 20 Sep 2026.