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· Registered
11 Posts
Discussion Starter · #1 · (Edited)
Everything seems to working ok, good power, up to 100mph on the Autobahn, starts right up, no hesitation, etc. There is a squeak (sorta like one of them box turkey calls) in the front driver side when going over bumps...guessing shocks, but want to fix the SES first. I have about 60K miles on it, stock/original parts except the radio, new tie rod ends, new tail lights/circuit boards, and new tires. No real servicing other than in 2003/2004 the AC would go on/off, and the dealer fixed that. I've been overseas with my TB since July 2004.

Most all of my driving is <6 miles at a time--military overseas, living on base. The SES light is off normally. If I drive like 20 miles/half hour or more, the light will come on, while driving on the Autobahn, stay on for about a week, and then turn off. This has happened 3 or 4 times, and want to find out what I need to do to fix it. I have auto hobby shops at my disposal for DIY repairs, but garages off base are hit and miss as to working on American cars.

Some of the codes I looked up are 4x4 related. The Service 4X4 light came on about two or three winters ago after a startup, remained on for the day, and was off before I got home, and never saw it again. I'm guessing those codes might be from that.

Besides the codes, I'm looking to do a bunch of maintenance on it soon, starting with the easy stuff. This site is an amazing resource!! I'm not a very educated mechanic, but willing to learn...a few buddies of mine are willing to help, so I am taking them up their assistance. I didn't know what tie rod ends were before two weeks ago when I failed inspection for them, but with their help, made my first repair on my TB.

And lastly, I get about 260 miles on a tank, so about 13MPG...a little low, but could be due to short trips. Before the codes, my buddy was thinking O2 sensor, but didn't look like those codes showed. I'll probably clean the throttle body, and get a new fuel filter and O2 sensor anyways and try those out to see if it helps, as it has for a lot of folks here it seems.

I had a buddy pull codes, here they are as displayed from the device...not all had descriptions. I'm going to get my own scanner in the next week or so to help nail this down. Thanks in advance for anything to point me in the right direction!! Anyways, here are the codes:

U1238 (History) (Immature)
C0305 Front Speed Sensor Malfunction (History) (Immature)
C0306 (History) (Immature)
C0324 (History) (Immature)
C0359 (History) (Immature)
C0374 General System Malfunction (History) (Immature)
C0379 (History) (Immature)

BO770 (History) (Immature)
BO775 (History) (Immature)
BO780 (History) (Immature)
BO790 (History) (Immature)
B2725 ATC Mode Switch Circuit Malfunction(History) (Immature)

C0237 Rear Wheel speed signal erratic (History)
C0281 Brake Switch Circuit(History)
U1152 Loss Of ACM Serial Data Communication

From looking up codes:
C0305 - Front Speed Sensor Malfunction
C0306 - Motor A or B Circuit
C0324 - T-Case Lock Circuit High
C0359 - Four Wheel Drive Low Range (4LO) Discrete Output Circuit
C0379 - Front Axle System
# B0770 - All Wheel Drive (AWD) Indicator Circuit
# B0775 - Four Wheel Drive High Range (4HI) Indicator Circuit
# B0780 - Four Wheel Drive Low Range (4LO) Indicator Circuit
# B0785 - Two Wheel Drive High Range (2HI) Indicator Circuit
# B0790 - Transfer Case Neutral Indicator Circuit

· Banned
2004 gmc
26,436 Posts
Yes. Forget the historical codes. See what CURRENT code is causing the SES light.

Squeak may be anti-sway bar bushings or end links or control arm bushings Upper or lower) or the plastic screw hood bumpstops even.

Careful and topical application of WD40 on one bushing at a time might show up the culprit.

· Registered
11 Posts
Discussion Starter · #3 ·
You might be on to something. It was a very dewey morning, and didn't notice the squeak going over the bumps. I was thinking shocks initially as I had a wobble on certain roads, but that seemed to go away with new tie rod ends

I don't know what those parts are or what they look like, but I'll do my homework, I promise!

I appreciate your insight and help!

I'll get the scanner on order this week, and when it comes in, I'll clear the codes, and go on a little road trip to see if I can get the light to trip again.
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