Thread: Cooling System Nightmare (P0117, P0116)

I've had an issue with my 06 GXP coolant temp gauge randomly bottoming out and jumping to beyond hot for about 4 months now. It does it randomly, then returns to normal temperature readings. I've flushed the coolant, replaced the temp sensor and thermostat, and back traced the pins from the temp sensor to the PCM. All of these things seem to be fine, but I still cant track down my issue. I don't know if it's related but the only time the horn has worked in the entire time I've owned the car was for a random week where I was having no electrical issues. This leads me to believe it must be something ground related but I can't figure out where any of the grounds go on the car. I hit a point where I decided to ignore the issue, but now that it's getting hotter outside the "A/C off for engine safety" is really starting to get on my nerves. Any suggestions, help, or ideas would be greatly appreciated.

I had actually checked the fuse box after posting this. Do you happen to have a diagram of the ground locations on the GXP's? That was going to be my next step

Originally Posted by tomsteve

along with what bandook suggested, check the length of the grounds themselves. a breach in the insulation= moisture and salt( i think illinois uses chloride now,too? that stuffs worse than salt) getting in there and wreaking havoc.
you can also hook up an ohm meter to the coolant temp wires and start wiggling them while its running. a meter with sound helps here. easier to just listen than to have to keep an eye on the meter.

Happen to have a diagram of the grounds on the GXP? That was going to be my next step. I back-traced the temp sensor with a multi meter and the wires for it checked out.