Service Bulletin #05-06-04-008A
Diagnostic Trouble Code (DTC) P1172 or P2636, Fuel Gauge Reads Empty, Service Engine Soon (SES) Light On (Relocate Auxiliary Fuel Tank Vent Hose)
Date: April 14, 2005
Document ID: 1647390
[GM Logo]
Subject: Diagnostic Trouble Code (DTC) P1172 or P2636, Fuel Gauge Reads Empty, Service Engine Soon (SES) Light On (Relocate Auxiliary Fuel Tank Vent Hose)
Models:
- 2001-2005 Chevrolet Silverado (Cab Chassis Models Only)
- 2001-2005 GMC Sierra (Cab Chassis Models Only) with Auxiliary Fuel Tank
Revision Note
This bulletin is being revised to clarify the difference between the auxiliary fuel tank balance hose and vent hose. Please discard Corporate Bulletin Number 05-06-04-008 (Section 06 -- Engine/Propulsion System).
Condition
Some customers may comment that the SES light comes on and the fuel gauge reads empty. This may occur when the vehicle is parked on an incline with the engine running.
Diagnosis with a scan tool may reveal a DTC P1172 and/or P2636.
Cause
Important: A similar condition may occur if the vehicle is fueled with the engine running AND the rear tank is fueled first. The engine must be shut off (as required by law) during vehicle refueling.
The auxiliary fuel tank vent hose is located in the same "T" connection on the main tank vent hose as the auxiliary tank balance hose. During fuel transfer, the fuel is pumped out of the auxiliary tank to the main tank via the balance hose. The fuel is then sucked back into the auxiliary tank via the vent hose rather than dumping the fuel into the main tank. When the Powertrain Control Module (PCM) does not detect a fluid level transfer between the main tank and the auxiliary tank, the PCM shuts off the auxiliary tank pump and the fuel gauge goes to empty.
Correction
| DO THIS | DON'T DO THIS |
|---|---|
| Relocate the auxiliary fuel tank vent hose. | Replace fuel level senders, fuel modules or PCMs. |
Service Procedure
Follow the service procedure below to correct this condition.
- Depending on the body upfitter, it may be necessary to raise the vehicle in order to gain access to the auxiliary tank balance hose. Refer to Lifting and Jacking the Vehicle in General Information (SI Document ID #899664).
- Depending on the body upfitter, it may be necessary to remove the left rear tire/wheel assemblies in order to gain access to the auxiliary tank balance hose. Refer to Tire and Wheel Removal and Installation (SI Document ID #656965).
- Locate the auxiliary fuel tank vent hose. The vent hose is the smaller diameter of the two hoses that comes from the auxiliary fuel tank and feeds into the main tank vent hose.
- Disconnect the auxiliary tank vent hose from the main tank vent hose connection. Refer to Quick Connect Fitting(s) Service (Metal Collar) (SI Document ID #802920).
- Install the cap supplied with kit, P/N 15213990, to the main tank vent hose connector where the auxiliary tank vent hose was just removed.
- Locate the section of vent hose on the main tank between the fuel filler neck and the metal pipe. The smaller of the two hoses on the filler neck.
- Cut the main tank vent hose between the filler neck and the metal pipe using an appropriate cutting tool.
- Install the "T" and the two hose clamps supplied with kit, P/N 15213990, into the main tank vent hose.
Tighten: Tighten the hose clamps to 2.5N·m(22 lb in).
- Install the new auxiliary tank vent hose and clamp supplied with kit, P/N 15213990, to the "T" that was just installed.
Tighten: Tighten the hose clamp to 2.5N·m(22 lb in).
- Connect the new vent hose to the original auxiliary tank hose.
- Secure the newly installed vent hose and the original auxiliary tank vent hose with plastic ties supplied in kit, P/N 15213990.
- If necessary, reinstall the left rear tires/wheels assemblies. Refer to Tire and Wheel Removal and Installation (SI Document ID #656965).
- If necessary, lower the vehicle.
- Using a scan tool, clear the DTCs.
- Start the vehicle and inspect for leaks.
[Diagram illustrating the rear axle and suspension area, highlighting fuel lines and connections.]
[Diagram showing a 'T' fitting being installed into a fuel hose, with hose clamps.]
Important: Advise the customer that a similar condition may occur if the vehicle is fueled with the engine running AND the rear tank is fueled first. The engine must be shut off (as required by law) during vehicle refueling.
Parts Information
| Part Number | Description | Qty |
|---|---|---|
| 15213990 | Kit, Aux Fuel Tank Hose Kit | 1 |
Parts are currently available from GMSPO.
Warranty Information
| Labor Operation | Description | Labor Time |
|---|---|---|
| J7802 | Hose, Filler Tube Vent, Aux Tank - Relocate | 0.4 hr |
| Add | R&R Left Rear Wheel | 0.2 hr |
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
[ASE Certified Logo]
For more details, visit: http://gsi.xw.gm.com/si/showDoc.do?docSyskey=1647390&from=sm
