Temp Gauge Jumps With Lights On

[jrhone]

New problem. Temp gauge jumps all the way to hot when I turn lights on at idle. Goes back to normal when I'm driving. If I switch on the electric fan while driving temp goes all the way up then goes back to normal slowly. It had an upgraded alternator and a new optima red top battery. Ideas?

[Chamonix72]

Have you grounded your gauge cluster? I'd try that first. It's cheap and it usually does the trick.

[jrhone]

yes i did the ground mod to the gauge cluster, but this isnt that it flickers.  Turn the lights on and t goes from1/3 up which is where it normally reads to ALL THE WAY up and stays there.  Lights also dim and brighten when revving.  If I drive, rev the car or turn the lights off the temp gauge jumps back down to normal.  Otherwise with my lights on and stationary the temp gauge is pegged on hot.  

[Chamonix72]

Hm. Well. My gas gauge was acting goofy and it turned out the multi-plug wasn't in all the way. That's my last cheap, easy suggestion. After this, I got nothin'.

[dbmw2002]

WoW Sounds like diptheria of the temp gauge, before sellin the car to an unsuspecting faqer, check this. My theria is start with basics, trade out the sending unit, I bought a brand new one and have ended up with my 40 year old part performing and the new in cds neighbs pool. Double check ground to gauge, the big tip though is dimming lights at idle, upgrades are great, if they work right, check all cons to batt, alt and reg. Drive down to homey OReillys and have the alt checked. I put a 320 rad in Riah and have been running hot ever since, will switch back to stock asap. Sounds like reg/alt troubles to me, not throwing right volts, ifin all cons are right

[jrhone]

Solved I think. I looked in my engine bay and saw the ground wire broken. Time to order a new one.

[Mike Self]

Don't forget to clean your fuses....those instruments operate on very small voltages/wattages and are really sensitive to resistance in the form of corrosion or bad ground paths...

 

mike