fault code on 2004 Trailblazer: low fan speed
 

Check engine light on, only one fault code appears: slow fan speed. I can erase the fault code, and drive for 50+ miles, or whatever without the "check engine" light coming on - but as soon as I stop and turn off the engine, to get gas for instance, as soon as I start back up, the check engine light comes in before I can get out of the driveway! It doesn't matter if I drive 5 miles or 50, the light remains out until I turn off the ignition, then restart!
I replaced the fan clutch last year and it cleared up for about 6 months, and now......IT'S BaaaaaaCK!
Any ideas? It can't get through inspection under present conditions.

whats the actual code?

Fault code on 2004 Trailblazer
 

Hey Cleveland, thanks for the quick response!
The fault code is P0526
Any suggestions? I'm going to check the plug connections - unplug and replug to make sure they're not loose.
While driving, I did also note that the water temperature is running at about 199 F. It typically ran at around 209 F over the years. My mechanic also replaced the T-stat a little over a year ago because of a "low temp" reading. It apparently was stuck in the open position.
Your thoughts?
Buddy

New Fan Clutch, still same fault code!
 

OK, I bit the bullet this weekend and installed a new fan clutch. I checked wires at fan shroud for chaffing, but OK.
I cleared the fault code and reset the check engine light. Started up and let it idle up to temperature - which is now about 208 degrees, it used to run at 211 degrees for years.
Drove a few miles to store, no light. Turned off ignition, went in to store for about 5 minutes. Returned, started engine, and "check engine" light came on before I dropped it in gear.
Again, it does not matter if I drive 8 miles or 80 miles - the light remains off until I stop the engine. When I restart the engine, the light comes back on, even if it is the next day before I restart it! Now, I'm beginning to think it is the PCM unit that is at fault. Any help guys?????? Thanks!

did you test the wires resistance/continuity? sometimes you can miss something with just a quick visual inspection. I've had wires broken inside the insulation but on the outside everything looked perfect. Wiring or the clutch would be the most likely suspects check anywhere that the harness is mounted, ziptied, angled or bent.

Thanks Cleveland
 

Will check continuity tonight. I do have the 5 volt reference, but will check the rest tonight , including grounds. Thanks for your help!
Buddy

New wrinkle in P0526 error code
 

Ok, removed and wirebrushed chasis surface and wire connections to assure good ground. Looked for wiring problems at entrance to ECU, pushed ECU plugs onto their respective mounts. Cleared the "check engine" light, and started the vehicle. No warning light appeared in the test drive of 12 miles. Got back home and shut off engine, waited a few minutes and re-started the engine.... immediate "check engine" warning light with out moving an inch! But this time the P0526 code was gone! It was replaced by P0340 code - camshaft position sensor! WTF!!!!!!!!
Beginning to suspect the ECU itself. The engine runs fine, as always, but at slightly lower operating temp than ever before, around 195 degrees.
Any thoughts.... anyone????