Engine Control Module Power Supply Relay -J271-, CHECKING

The following procedure is used to diagnose the Motronic Engine Control Module Power Supply Relay -J271-.

Special tools and workshop equipment required

Multimeter.
Wiring diagram.
Scan tool.

Test requirements

Fuses OK.
Battery voltage OK.
Switch OFF all electrical and electronic accessories.
Vehicles with Auto. Transmission, ensure Selector Lever position is in "P".
Vehicles with Man. Transmission, ensure Shifter Lever position is in "N" with Parking Brake applied.
Coolant Temperature: ≥ 80° C.
Observe all safety precautions: SAFETY PRECAUTIONS .
View clean working conditions: CLEAN WORKING CONDITIONS .

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers complaint. Refer to PRELIMINARY CHECK . -- Was complaint verified?	YES: GO TO Step 2. NO: GATHER more information from customer about the complaint.
2	REMOVE: Motronic Engine Control Module Power Supply Relay -J271-. Refer to the appropriate repair information. CHECK: Motronic Engine Control Module Power Supply Relay -J271- harness connector terminal 1 to ground for voltage. CHECK: Motronic Engine Control Module Power Supply Relay -J271- harness connector terminal 3 to ground for voltage. CHECK: Motronic Engine Control Module Power Supply Relay -J271- harness connector terminal 5 to ground for voltage. SPECIFIED VALUE: Battery voltage. -- Were values obtained?	YES: GO TO Step 3. NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 4.
3	REMOVE: Engine Control Module -J623-. Refer to the appropriate repair information. CHECK: Motronic Engine Control Module Power Supply Relay -J271- harness connector terminal 2 to Engine Control Module -J623- harness connector terminal T91 / 87 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was value obtained?	YES: REPLACE: Engine Control Module -J623-. Refer to the appropriate repair information. PERFORM: Road Test to verify repair. FAULT DOES NOT RETURN: Generate readiness code. Refer to READINESS CODE . GO TO: Step 4. NO: PERFORM: Visual Inspection of wiring and component. CHECK: Wiring for open, high resistance, short or harness connector for damage, corrosion, loose or broken terminals. REPAIR: Faulty wiring or connector. GO TO: Step 4.
4	Final Procedure Perform a road test to verify repair. Do any DTC's return:	YES: Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY . Perform the diagnostic procedure for that DTC. NO: Repair is complete. Generate readiness code. Refer to READINESS CODE . Return vehicle to Customer.