Voltmeter and temp guage (Page 1/1)
creaky78 OCT 02, 06:22 PM
Voltmeter on my 87 GT reads around 13V with key on, engine not running. When I start the engine, the needle indicates about 15V, but after the engine runs a few minutes, the needle maxes out and stays there. Voltage check shows when running indicates around 14V even though the gauge is pinned. Temp gauge reads approx 100 degrees when starting the engine, goes to about 160 degrees when warmed up but a laser temp gauge shows engine temp to be 180-190. I know it is not a critical issue, but OCD me would like to fix this.
Rexgirl OCT 02, 08:41 PM
With the ignition on, check the voltage on both sides of the "Gauges" fuse. If it measures the same as your battery, then check ground G 201, located to the right of the instrument cluster and above the center console.
theogre OCT 03, 12:29 AM
Above May help or not...
Most Cabin things go to 2 grounds, G201 & G202, but diagrams often don't show that.
See my Cave, Wire Service

For Volt gauge problems... always check volts w/ a real gauge in back.
High Volts will wreck many things including ECM. ECM may trip codes too if problem last more then a few seconds but Don't trust a code for this. CEL/MIL light may blink or stay On during high volt.

help or not because Dash gauges often lie and problem(s) can be anywhere.
Example: my oil gauge is nearly always "pegged" even after cleaning/fixing most grounds, replacing sender, gauge, even replace the engine.
Even tested w/ ~ 45 & 90Ω resistors and gauge still way off.
Think somewhere in wiring between sender to gauge is adding resistance so the gauge lies. Even the dash board and connectors and clips used there can have crap connection at 1 or many points.

Clean/Fix all ground in the engine bay. May not fix current issue but helps guessing and does help a lot of other problems. Use silicone or brake grease for any wire bolted/screwed to block etc.

Temp gauge reading "off" isn't easy to check w/ IR on outside of engine.
Try pointing that at the sender or intake manifold next to it. May read close to same.
Pointed anywhere else then IR unit may lie too because Engine Temp at a given point can be way different.
If has T-stat or other problems then sender and ECM's ECT maybe correct reading high for V6. But may not "boil over" because local hot spots may not make this happen.
See my Cave, Crushed Pipe and rest of section.

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

creaky78 OCT 03, 06:17 PM
Thanks guys, I will check all that you have posted and hope for the best.