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

Function

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 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. Refer to: SAFETY PRECAUTIONS .
View clean working conditions. Refer to: 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 . -- NO: GATHER more information from customer about the complaint.
2	DISCONNECT: Motronic Engine Control Module Power Supply Relay -J271- from the SB Fuse box in the engine compartment. CHECK: Motronic Engine Control Module Power Supply Relay -J271- socket terminal 30 to ground for voltage. CHECK: Motronic Engine Control Module Power Supply Relay -J271- socket terminal 85 to ground for voltage. SPECIFIED VALUE: Battery voltage. -- Were Values obtained?	-- YES: GO TO: Step 3 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING . -- 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, SB fusebox or connector. REPLACE: Any open fuses. GO TO: Step 6 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING .
3	REMOVE: Engine Control Module -J623-. Refer to appropriate repair service information. CONNECT: Jumper wire, Motronic Engine Control Module Power Supply Relay -J271- socket terminals 30 and 87. CHECK: Engine Control Module -J623- harness connector T94 / 3, 5 and 6 to ground for voltage. SPECIFIED VALUE: Battery voltage. -- Were Values obtained?	-- YES: GO TO: Step 4 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING . -- NO: GO TO: Step 5 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING .
4	REMOVE: Jumper wire, Motronic Engine Control Module Power Supply Relay -J271- socket terminals 30 and 87. CHECK: Motronic Engine Control Module Power Supply Relay -J271- socket terminal 86 to the Engine Control Module -J623- harness connector T94 / 69 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 repair service information. GO TO: Step 6 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING . -- 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. REPLACE: Any open fuses. GO TO: Step 6 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING .
5	REMOVE: Jumper wire, Motronic Engine Control Module Power Supply Relay -J271- socket terminals 30 and 87. REMOVE: Engine Control Module -J623-. Refer to appropriate repair service information. REMOVE: Fuse 11 (On Fuse Panel B) -SB11-. Refer to appropriate repair service information. CHECK: Downstream (output) side of Fuse 11 (On Fuse Panel B) -SB11- to Engine Control Module -J623- harness connector T94 / 3, 5 and 6 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Fuse Panel B -SB- fuse box. Refer to appropriate repair service information. GO TO: Step 6 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING . -- 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. REPLACE: Any open fuses. GO TO: Step 6 Motronic Engine Control Module Power Supply Relay -J271-, CHECKING .
6	Final Procedure Perform a road test to verify repair. Do any DTC's return:	-- YES: FAULT DOES RETURN: REPLACE: Engine Control Module - J623-. Refer to appropriate repair service information. FAULT DOES NOT RETURN: 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.