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

WARNING: This page is about a different car, the 2010 Audi Q7, 2009 Audi Q7, 2008 Audi Q7, and 2007 Audi Q7. However, it is still accessible from the selected car via links, so may be relevant.

General Description

The Engine Control Module -J623- tells 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.

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.
Coolant Temperature: ≥ 80° C.
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

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 -- 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 terminals 3 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 connector. CRANK: Engine. CHECK: Fuel Delivery Unit -GX1- harness connector terminals 1 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 repair 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 terminal 1 to the Fuel Pump Control Module -J538- harness connector terminal 1 for resistance. CHECK: Fuel Delivery Unit -GX1- harness connector terminal 4 to the Fuel Pump Control Module -J538- harness connector terminal 2 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 Control Module -J623-. Refer to appropriate repair information. CHECK: Fuel Pump Control Module -J538- harness connector terminal 5 to Engine Control Module -J623- harness connector terminal T94 / 70 for resistance. SPECIFIED VALUE: 0.5 Ω (± 0.3 Ω). -- Was Value obtained?	-- YES: REPLACE: Fuel Pump Control Module -J538-. Refer to appropriate repair 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 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 repair information. Clear the DTCs. 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.