eames23

My Problem. Turn the headlights on and the temp gauge goes through the roof.

I understand this is VERY common to our Foxes. Everyone recommends checking grounds first. On that note I have since replaced the ground from Firewall to back of driver side cylinder-head. Replaced negative battery cable and made sure ground to frame was good. Next, I replaced ignition switch. No joy.

A few anomalies I have noticed. When messing w/ dimmer switch the temp will go up/down. Same for when I hit turn signals/brights. I'm thinking it could be one of the following but your opinions are appreciated and maybe you'll see a connection I don't:

1. bad dimmer switch
2. bad ICV in gauge cluster
3. bad headlight switch
4. bad turn signal switch
5. bad ECT sensor

Thanks Ahead!

mattdel

The gauges are doing that because you're sending voltage into the cluster ground, which is shared by: main light switch, hazard warning switch, exterior light warning chime, and heater control illumination. Figure out which one of those is feeding voltage into the ground circuit.

eames23

Thanks for the response mattdel. Excuse my ignorance regarding electrical wiring but another few questions. Could you possibly point me in the direction of a wiring diagram for instrument gauges showing grounds and such? Also, what would you recommend as the preferred method for finding which of those switches is feeding voltage into the ground circuit? I'm a newb so I appreciate your patience/help greatly.

I know this is a common issue but I've yet to find a definitive thread on the Google Machine

eames23

Any hints on where the instrument cluster ground is located?

Going off the below diagram:
http://www.auto-wiring-diagram.com/w...generation.jpg

TrimDrip

Connector B9

eames23

TrimDrip - You Rock! I was going blind on reading wiring diagrams from the ol' Chilton Manual and you posted. Thanks a million. Started looking at that plug just as you posted...and guess what....the ol' Nickel and Dime wiring job. Getting late but I'm pretty sure I'm getting close. TWSS

eames23

Eeesh....Everything is wrong on this two connectors per this URL:

http://diagrams.hissind.com/?p=257

I should have known better than buying a car in Arkansas lol. Hopefully the above is accurate for 92 and up...but either way...I feel a lot better now. Thanks all for the help again. I'll post up when I get the wires situated per the diagram.

eames23

Please tell me there's a trick to pulling wires out of these harnesses. I'm probably being too delicate but I'm afraid I'll break harnesses and really be SOL.

eames23

Meh...NM...push down on the plastic piece below and not the metal one on top.

eames23

Looks like all the wires were in their collective locations.

Back to square one. I did notice one thing tonight. If I removed the dimmer switch the temp gauge would behave with lights on. I'm really in need of some help guys.

I'll buy a multimeter this wknd and start testing wires. That being said, I've never used a multimeter before. What kind of voltage should I be looking for on Instrument Cluster wires and/or what would lead me to believe a wire is bunk?

Thanks for putting up with me and all the help so far.