Reducing Agent Heater Control Module - J891-, Checking

General Description

The Reducing Agent Heater Control Module -J891- controls the reducing agent heater functions.

NOTE:

Reducing Agent Reservoir Sensor -G697-, Reducing Agent Reservoir Processing Unit -G698-, Reducing Agent Tank Heater (Heating Circuit 1) -Z102-, Reducing Agent Temperature Sensor -G685-, and Reducing Agent Heater Control Module J891 are all contained within the Reducing Agent Delivery Unit Located inside the Adblue tank. Should one component be faulty, the whole assembly will need to be replaced.

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. -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. DISCONNECT: Reducing Agent Heater Control Module -J891- harness connectors. IGNITION: ON. CHECK: Reducing Agent Heater Control Module -J891- harness connector T5ai / 3 and 5 to ground for voltage. IGNITION: OFF. 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 5.
3	REMOVE: Engine Control Module -J623-. Refer to appropriate Service Information. CHECK: Reducing Agent Heater Control Module -J891- harness connector T4qc / 1 to the Engine Control Module -J623- harness connector T91 / 28 for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector T4qc / 2 to the Engine Control Module -J623- harness connector T91 / 37 for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector T4qc / 3 to the Engine Control Module -J623- harness connector T91 / 11 for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector T4qc / 4 to the Engine Control Module -J623- harness connector T91 / 36 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: 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 5.
4	CHECK: Reducing Agent Heater Control Module -J891- harness connector T5ai / 1 to ground for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector T5ai / 2 to ground for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector T5ai / 4 to ground for resistance. SPECIFIED VALUE: 1 - 5 Ω (@ approx. 25° C). -- Were Values obtained?	-- YES: REPLACE: Reducing Agent Heater Control Module -J891-. Refer to appropriate Service Information. GO TO: Step 5. -- NO: PERFORM: Visual Inspection of wiring and components. 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 5.
5	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.