Reducing Agent Heater Control Module -J891-, Checking

General Description

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

The Reducing Agent Heater Control Module -J891- contains the following components:

Reducing Agent Heater Control Module -J891-
Reducing Agent Line Heater (Heating Circuit 2) -Z104-

The Reducing Agent Heater Control Module -J891- components cannot be serviced separately, and must be serviced as a unit.

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.
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 Reducing Agent Heater Control Module -J891-, CHECKING - 2 . -- NO: GATHER more information from customer about the complaint.
2	IGNITION: OFF. DISCONNECT: Reducing Agent Heater Control Module -J891- harness connector. IGNITION: ON. CHECK: Reducing Agent Heater Control Module -J891- harness connector terminals 3 and 5 to ground for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- Were Values obtained?	-- YES: GO TO: Step 3 Reducing Agent Heater Control Module -J891-, 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 4 Reducing Agent Heater Control Module -J891-, CHECKING - 4 .
3	REMOVE: Engine Control Module -J623-. Refer to appropriate repair manual. CHECK: Reducing Agent Heater Control Module -J891- harness connector 1 to the Engine Control Module -J623- harness connector T94 / 41 for resistance. CHECK: Reducing Agent Heater Control Module -J891- harness connector 2 to the Engine Control Module -J623- harness connector T94 / 31 for resistance. CHECK: Reducing Agent Metering System Control Module -J880- harness connector 3 to the Engine Control Module -J623- harness connector T94 / 40 for resistance. CHECK: Reducing Agent Metering System Control Module -J880- harness connector 4 to the Engine Control Module -J623- harness connector T94 / 9 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: REPLACE: Reducing Agent Heater Control Module -J891-. Refer to appropriate repair manual. GO TO: Step 4 Reducing Agent Heater Control Module -J891-, CHECKING - 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 Reducing Agent Heater Control Module -J891-, CHECKING - 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. 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. If all electrical connections are OK: REPLACE: Engine Control Module -J623-. Refer to appropriate repair manual. 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.