Automatic Glow Time Control Module - J179- And Glow Plug Checking

General Description

The glow plugs are activated by the Engine Control Module -J623- through the Automatic Glow Time Control Module -J179-. The voltage on the individual glow plugs is adjusted over the frequency of the PWM pulses. For quick start with an ambient temperature of less than 64° F (18° C), a maximum voltage of 11.5 volts is present during preheating. This ensures that the glow plug heats up as quickly as possible (maximum two seconds) to over 1832° F (1, 000° C), thus reducing the preheating time of the engine. Post-heating is performed up to a coolant temperature of 64° F (18° C) after the engine start for a maximum of five minutes. Post-heating helps reduce hydrocarbon emissions and combustion noise during the engine warm-up phase.

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 .

NOTE:

The Glow Plug terminal / connector is not repairable. The harness must be replaced if damaged.

Test Procedure

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers concern. Refer to PRELIMINARY CHECK . -- Was Concern verified?	-- YES: GO TO: Step 2. -- NO: GATHER more information from customer about the complaint.
2	Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY . -- Are fault codes present for the Glow Plugs -- ?	-- YES: GO TO: Step 5. -- NO: GO TO: Step 3.
3	DISCONNECT: Automatic Glow Time Control Module -J179- harness connector. IGNITION: ON. CHECK: Automatic Glow Time Control Module -J179- harness connector terminals 6 and 11 to ground for voltage. CHECK: Automatic Glow Time Control Module -J179- harness connector terminal 7 to battery voltage for voltage. SPECIFIED VALUE: Battery voltage. IGNITION: OFF. -- 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 7.
4	CHECK: Automatic Glow Time Control Module -J179- harness connector terminal 10 to Engine Control Module -J623- harness connector terminal T91 / 55 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: REPLACE: Automatic Glow Time Control Module -J179-. Refer to appropriate Service Information. GO TO: Step 7. -- 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 7.
5	DISCONNECT: Automatic Glow Time Control Module -J179- harness connector. IGNITION: ON. CHECK: The faulty Glow Plug -- (Per DTC Stored) connector terminal to ground for resistance. Refer to the proper wiring diagram for terminal and connector location. SPECIFIED VALUE: 1.3 Ω (+/- 0.3 Ω at about 20° C). IGNITION: OFF. -- Was Value obtained?	-- YES: GO TO: Step 6. -- NO: REPLACE: The faulty Glow Plug --. Refer to appropriate Service Information. GO TO: Step 7.
6	CHECK: Automatic Glow Time Control Module -J179- harness connector terminals 1, 2, 3, 4, 5, 8 to faulty Glow Plug -- terminals for resistance. (Refer to the proper wiring diagram for terminal and connector location). SPECIFIED VALUE: 0.5 [Ω] (+/- 0.3 Ω). IGNITION: OFF. -- Was Value obtained?	-- YES: REPLACE Automatic Glow Time Control Module -J179- Refer to appropriate Service Information GO TO: Step 7. -- 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 7.
7	Final Procedure Perform a road test to verify repair. Do any DTC's return:	-- YES: Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY . Perform the diagnostic procedure for that DTC. FAULT RETURNS: no malfunction are detected in the wiring. REPLACE: Engine Control Module - J623-. Refer to proper Service Information for removal and replace procedures. -- NO: Repair is complete, Generate readiness code. Refer to READINESS CODE . Return vehicle to Customer.