Automatic Glow Time Control Module -J179- AND GLOW PLUG CHECKING

Function

The glow plugs are activated by the Engine Control Module -J623- over theAutomatic Glow Time Control Module -J179-. The voltage on the individual glow plugs is adjusted over the frequency of the PWM impulses. 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 (1000°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

Test Requirements

A/C switched off
All electrical consumers switched off
Battery voltage at least 12.5 volts
Engine control module fuses OK
Ground connections between engine/transmission/chassis OK
Ignition switched Off
Vehicles with automatic transmission, shift selector lever in park or neutral

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 concern
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. CHECK: Automatic Glow Time Control Module -J179- harness connector terminals 7 to Battery voltage. SPECIFIED VALUE: Battery voltage IGNITION: OFF -- Was Value obtained?	-- YES: GO TO: Step 4 -- NO: CHECK: wiring for open, high resistance, short or electrical connector for damage, corrosion, loose or broken terminals REPAIR: faulty wiring or connector REPLACE: any open Fuses 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 repair information GO TO: Step 7 -- NO: CHECK: wiring for open, high resistance, short or electrical 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 T6t / x 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 repair 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 T6t / xx 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 repair information GO TO: Step 7 -- NO: CHECK: wiring for open, high resistance, short or electrical 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 repair information for removal and replace procedures. -- NO: Repair is complete, Generate readiness code. Refer to READINESS CODE . Return vehicle to Customer