Fuel Delivery Unit - GX1- / Fuel Pump Control Module - J538-, Checking

General Description

The engine /Motor Control Module -J623- informs the Fuel Pump Control Module -J538- the demand needed for fuel volume and pressure and activates the Transfer Fuel Pump -G6-. The Transfer Fuel Pump -G6- transfers fuel to the rest of the fuel system, where it is monitored by the engine /Motor Control Module -J623- through sensors, and controlled through regulators and/or metering valves.

Note the Transfer Fuel Pump -G6- is also known as the Fuel Delivery Unit -GX1-.

The Fuel Delivery Unit -GX1- contains the following components:

Transfer Fuel Pump -G6-.
Fuel Level Sensor -G-.

The Fuel Delivery Unit -GX1- components cannot be serviced separately, and they 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 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

NOTE:

When the door is opened or the ignition is turned to the ON position the fuel pump is activated for 2 seconds to build up the pressure in the fuel system.

Step	Procedure	Result / Action to Take
1	PERFORM: Preliminary Check to verify the customers concern. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2. -- NO: GATHER more information from customer about the complaint.
2	IGNITION: ON. LISTEN: Fuel Delivery Unit -GX1- should be heard running for 2 s. IGNITION: OFF. SPECIFIED VALUE: Transfer Fuel Pump ON for 2 s. -- Was Value obtained?	-- YES: CONDITION: May be intermittent. 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. -- NO: GO TO: Step 3.
3	DISCONNECT: Fuel Pump Control Module -J538- harness connector. IGNITION: ON. CHECK: Fuel Pump Control Module -J538- harness connector terminal 5 to 4 for voltage. CHECK: Fuel Pump Control Module -J538- harness connector terminal 4 to battery voltage for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- 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	RECONNECT: Fuel Pump Control Module -J538- harness connector. DISCONNECT: Fuel Delivery Unit -GX1- harness connectors. CRANK: engine. CHECK: Fuel Delivery Unit -GX1- harness connector T4ap / 1 to T4ap / 4 for voltage while engine is cranking. IGNITION: OFF. SPECIFIED VALUE: 7 - 11 V. -- Was Value obtained?	-- YES: REPLACE: Fuel Delivery Unit -GX1-, Refer to appropriate Service Information. GO TO: Step 7. -- NO: GO TO: Step 5.
5	DISCONNECT: Fuel Pump Control Module -J538- harness connector. CHECK: Fuel Delivery Unit -GX1- harness connector T4ap / 1 to the Fuel Pump Control Module -J538- harness connector terminal 3 for resistance. CHECK: Fuel Delivery Unit -GX1- harness connector T4ap / 2 to the Fuel Pump Control Module -J538- harness connector terminal 2 for resistance. CHECK: Fuel Delivery Unit -GX1- harness connector T4ap / 3 to the Fuel Pump Control Module -J538- harness connector terminal 1 for resistance. CHECK: Fuel Delivery Unit -GX1- harness connector T4ap / 4 to ground for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: GO TO: Step 6. -- 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.
6	REMOVE: engine /Motor Control Module -J623-. Refer to appropriate Service Information. CHECK: Fuel Pump Control Module -J538- harness connector terminal 6 to the engine /Motor Control Module -J623- harness connector T91 / 42 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: REPLACE: Fuel Pump Control Module -J538-. 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. -- Does the original DTC return?	-- YES: CHECK: engine /Motor Control Module -J623- harness connector for any damaged, pushed-out pins. REPAIR: As necessary. If all electrical connections are OK: REPLACE: engine /Motor 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.