This morning, I was able to tear into a power seat issue and trace the bad orange wire to the seat plug and get my power seat working.
Downside is now the gas gauge is pegged to the 5 o'clock position and the low fuel light is working as there is low fuel in the tank. errr. I've read that this could be due to a bad ground. The gauge worked fine until I tore into the harness under the driver's side carpet so I am thinking I inadvertantly may have caused damage to the ground wire in that area. again...errrr. My question is if there is a specific ground wire I should be concentrating on in that part of the harness as it seemed like there were multiple ones and how can I test the ground with a test light? I was thinking about clipping the test light to a jumper off the fuse panel and probing the ground wires. Am I on the right track as I don't want to do any more damage to the harness. Suggestions and advice is greatly appreciated at this point before I pull my hair out. Thanks in advance!
I love the forum and the info that I get from everyone here!
racechaplain

 

What on earth did you do to that poor wiring harness?

You don't say what year yours is, but 2001 Blazer gas gauges are controlled by the PCM, based on a signal circuit sent through the sending unit in the tank back to the PCM. As with old cars, an open anywhere in this sending unit circuit would cause the gauge to read overfull. Fuel level signal to the PCM is on the purple wire. Low level reference to the PCM is black/white. There that should get you going. Be careful to not put power to any circuit going to the PCM, even through a test light. PCMs are not designed to control test lights and provide a ground for their bulbs! Gotta know what's on the other end of a wire and how things work before you start doing things! I never work on electrical problems without a factory wiring schematic. AllDataDIY.com has them with their subscriptions + I always buy a set of factory manuals for my vehicles. Set for my Blazer was pretty pricey, but is definitely worth it if you expect to fix much on a second gen Blazer.

 

Crazy, but when I disconnected the pwr. seat harness at the carpet and pushed the ground wire back up into the socket and reinstalled, the gas gauge worked! Quick fix that I was very thankful for.

 

now I just gotta figure out the pwr. seat harness and gas gauge on my 96'! ugh! The needle on the 96' is always on the empty. New fuel pump module in it too so I'm not sure if it is the sending unit but not surprised since it was a cheapy. lessons learned!

 

Glad to hear you have it working correctly again.