5.3 Multiple Issues & Solutions

[brianelton]

Hey guys, this is my first post.

I own a 2003 Avalanche. Over the years I have done quite a bit of work on this Avalanche and decided I'd like to share the symptoms and solutions:

Hard to start - turn key on/off several times and it starts right up. Without troubleshooting I replaced the fuel pressure regulator (FPR). (I think only 2002 & 2003 models have the FPR on the rail, the rest are in the tank with the fuel pump. Issue still existed. Hooked up fuel press gauge - turn key on/off several times, pressure eventually builds to 55 psi, but immediately drops to zero. I assumed check valve on fuel pump bad - cut out floor board and replaced pump with a brand new AC Delco pump. Issue still existed. Stumped! I disconnected fuel return line at the rail and put a quick connect line on it with a schrader valve. Turn key on - pressure builds up to like 80psi and holds forever. At that point I hit the schrader valve on the return side - pressure dropped to zero. FPR was not holding back the pressure. Brand new FPR was bad out of the box. Got new FPR, issue resolved. FYI...neither of the bad FPR's leaked gas out the nipple, and both raised the fuel pressure by +5 psi when running with vacuum line off.

I forget the codes, but years ago my truck would run like poo when outside temp was below 48 degrees F. After truck warmed up, it ran fine. Threw a "Lean in Bank 2" code. Theory - intake gasket shrinking when cold, expanding when warmer. Replaced intake gaskets. Issue resolved.

Roaring noise in rear. Took rear diff pan off. Covered in metal. Took carrier out. Inspected carrier. Pasenger side carrier bearing pitted like a mofo. Bought a new bearing, carried to service dept at dealer, and kindly asked them to press old one off and put new one on. No charge. Uh oh, carrier won't go back in! Read all the scary stuff about backlash, blah blah blah. Crap. Now what? Well, it has to go back in! I don't remember for sure, but I think I filed down the passenger side shim with a hand file - file/try, file/try, file/try over and over until I could beat it in with a mallet. Its been fine for years.

Clunk sound when turning. Body mounts are shifting. Shim the body mounts. Issue resolved.

Vibration in steering. Replaced intermediate shaft. Issue resolved.

A/C blows hot when idling in traffic on hot Louisiana days. Installed an extreme duty fan clutch to make it pull more air across the condenser. That solved that problem! The fan will make a bit of noise when you first start and drive truck for first minute or two.

Wheel roaring. Replaced front driver side hub.

Service air bag light. Had dealer pull air bag code for me (a regular OBD wont do it). Had code 044. It cant see the air bag in steering wheel. Troubleshot the SIR Coil aka Clockspring aka Clock spring - remove connector under dash (not the one behind the kick panel), connector is designed to ground out pins when disconnected. Remove air bag (easy). Put test leads in each air bag connector - should have continuity. Turn steering wheel from extreme left to right and make sure continuity maintains. One connector OK. Other connector loses continuity intermittently throughout steering range right of center.

Issues I haven't worked too hard on yet -
Carpet getting wet on passenger side front when it rains a lot. Appears water is entering underneath the carpet. I havent looked into it at all yet, but first guess is clogged sunroof drain.

Twice I get audible alert and message on the DIC "Service Brake System" and ABS goes into disabled mode. I turn truck on and off and issue goes away. Has only happened when driving on Interstate at steady high rate of speed and driving straight. I think there were a bunch of codes indicating loss of connectivity to the brake control module. Brake control module going bad or bad connection? Pulled harness, sprayed with contact cleaner and inserted dialectic grease in connector pins.

Speed gauge off by 10mph or so - more off at higher speeds. Had about 100,000mi and was about 8 years old. Called GM Service. I got the guy all flustered and somehow and for some reason he said GM would pay for it if it was determined to be a failure of the part. I took to the dealer, got new gauge cluster, paid for it out of pocket, called GM Service center, requested reimbursement, they declined, I played back the call recording, after a few calls with some supervisor/manager chick, they finally sent me a check.

It sounds like I have done a lot, but it has been a good truck for 140,000mi. The gauge was expensive. The clock spring is expensive (b/c I have steering wheel controls) but I got a used one from salvage. All in all, I havent spent that much money on it.

I hope all these problems and solutions help someone else!