Reducing Agent Heater Control Module -J891-, CHECKING

General Description

This procedure can be used to diagnose the Reducing Agent Heater Control Module -J891-, which controls the reducing agent heaters.

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 .

For Hybrid vehicles refer to: HIGH VOLTAGE SYSTEM GENERAL WARNINGS .

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 T5ai / 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 4.
3	REMOVE: Engine Control Module -J623-. Refer to appropriate Service Information. DISCONNECT: Reducing Agent Tank Heater (Heating Circuit 1) -Z102- harness connector. DISCONNECT: Reducing Agent Pump Heater (Heating Circuit 2) -Z103- harness connector. DISCONNECT: Reducing Agent Line Heater (Heating Circuit 2) -Z104- harness connector. 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. CHECK: Reducing Agent Heater Control Module -J891- harness connector T5ai / 1 to the Reducing Agent Line Heater (Heating Circuit 2) -Z104- harness connector terminal 2 for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector T5ai / 2 to the Reducing Agent Pump Heater (Heating Circuit 2) -Z103- harness connector terminal 2 for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector T5ai / 4 to the Reducing Agent Tank Heater (Heating Circuit 1) -Z102- harness connector terminal 2 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Reducing Agent Heater Control Module -J891-. Refer to appropriate Service Information. 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. -- 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.