Motronic Engine Control Module Power Supply Relay - J271-, CHECKING

General Description

The following procedure is used to diagnose the Motronic Engine Control Module Power Supply Relay -J271- and the Engine Control Module -J623- power supply voltage that is provided by 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 automatic transmission, ensure the selector lever position is in "P".
Vehicles with manual transmission, ensure the shifter lever position is in "N" with the parking brake applied.
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 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 2 . -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. DISCONNECT: Motronic Engine Control Module Power Supply Relay -J271- from the Fuse Panel B -SB- in the engine compartment (refer to appropriate wiring diagram). IGNITION: ON. CHECK: Motronic Engine Control Module Power Supply Relay -J271- terminals B1 and 41 to ground for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- Were Values obtained?	-- YES: GO TO: Step 3 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 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 6 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 6 .
3	REMOVE: Engine Control Module -J623-. Refer to appropriate service information. CONNECT: Jumper wire, between the Motronic Engine Control Module Power Supply Relay -J271- terminals B1 and 3A. IGNITION: ON. CHECK: Engine Control Module -J623- harness connector T91a / 5 and T91a / 6 to ground for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- Were Values obtained?	-- YES: GO TO: Step 4 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 4 . -- NO: GO TO: Step 5 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 5 .
4	DISCONNECT: Jumper wire, between the Motronic Engine Control Module Power Supply Relay -J271- socket terminals B1 and 3A. CHECK: Motronic Engine Control Module Power Supply Relay -J271- terminal 42 to the Engine Control Module -J623- harness connector T91a / 7 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: REPLACE: Motronic Engine Control Module Power Supply Relay -J271-. Refer to appropriate service information. GO TO: Step 6 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 6 . -- 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 6 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 6 .
5	DISCONNECT: Jumper wire, between the Motronic Engine Control Module Power Supply Relay -J271- socket terminals B1 and 3A. REMOVE: Appropriate fuse (refer to appropriate wiring diagram for correct fuse). CHECK: Downstream (output) side of appropriate fuse to the Engine Control Module -J623- harness connector T91a / 5 and T91a / 6 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Fuse panel. Refer to appropriate service information. GO TO: Step 6 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 6 . -- 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 6 Motronic Engine Control Module Power Supply Relay - J271-, CHECKING - 6 .
6	Final Procedure Perform a road test to verify repair. -- Does the original DTC return?	-- YES: CHECK: Engine Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: Engine Control Module -J623-. Refer to appropriate service information. Clear the DTC's. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY . Repair is complete. Generate Readiness Code. Refer to READINESS CODE . Return vehicle to Customer. -- NO: Perform the diagnostic procedure for any DTC's. If no DTC's return, the repair is complete. Return vehicle to customer.