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

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General Description

The Engine 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 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-.

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 complaint. Refer to PRELIMINARY CHECK . -- Was Complaint verified?	-- YES: GO TO: Step 2 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 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 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 7 . -- NO: GO TO: Step 3 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 3 .
3	DISCONNECT: Fuel Pump Control Module. -J538- harness connector. IGNITION: ON. CHECK: Fuel Pump Control Module -J538- harness connector terminal 5 to 4 and to ground for voltage. CHECK: Fuel Pump Control Module -J538- harness connector terminal 4 to battery positive for voltage. IGNITION: OFF. SPECIFIED VALUE: Battery voltage. -- Were Values obtained?	-- YES: GO TO: Step 4 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, 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 7 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 7 .
4	RECONNECT: Fuel Pump Control Module -J538- harness connector. DISCONNECT: Fuel Delivery Unit -GX1- harness connector. CRANK: Engine. CHECK: Fuel Delivery Unit -GX1- harness connector terminals 2 to 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 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 7 . -- NO: GO TO: Step 5 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 5 .
5	DISCONNECT: Fuel Pump Control Module -J538- harness connector. CHECK: Fuel Delivery Unit -GX1- harness connector terminal 2 to the Fuel Pump Control Module -J538- harness connector terminal 2 for resistance. CHECK: Fuel Delivery Unit -GX1- harness connector terminal 4 to the Fuel Pump Control Module -J538- harness connector terminal 4 for resistance. CHECK: Fuel Delivery Unit -GX1- harness connector terminal 4 to ground for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Were Values obtained?	-- YES: GO TO: Step 6 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 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 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 7 .
6	REMOVE: Engine Control Module -J623-. Refer to appropriate service information. CHECK: Fuel Pump Control Module -J538- harness connector terminal 6 to the Engine Control Module -J623- harness connector T91 / 9 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 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 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 Fuel Delivery Unit -GX1- / Fuel Pump Control Module -J538-, CHECKING - 7 .
7	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.