temp gauge issues

takotruckin · Post by **takotruckin** » Tue May 29, 2007 6:35 pm

sorry for the long winded post here...
for background, my baja runs a watercooled v6, so i run a coolant temp gauge to keep an eye on the engine. my thermo switch for the fan went out, so i hot wired it to run any time the key is on.
i logged alot of driving time in the dunes this weekend and noticed something odd. during the day (70*-80* F), the car runs at about 190, give or take (180 tstat), never really goes over 200. but when i went out at night (50*-60*) the guage kept going back and forth from like 190-225*, im thinking that the 2 headlights and 4 offroad lights all being on had something to do with it. is there any chance of this? i have a 110A alt, so the car should have enough juice to run everything. but its almost like the lights being on is making the gauge read high for some reason, is this possible?

Speedy Jim · Post by **Speedy Jim** » Tue May 29, 2007 6:58 pm

Switch the lights on and off repeatedly and watch the gauge.

You could also connect a multimeter to monitor the voltage
going to the gauge (from fuse) and see if it varies a lot.

It could also be a ground loop issue. This can occur if there is
a small resistance between engine and chassis ground.
Current flowing from the alternator (for example) will create a
small voltage in the ground return which will affect a gauge sender
since it is in the same path.

MNAirHead · Post by **MNAirHead** » Tue May 29, 2007 9:15 pm

Speedy..

Definition request

http://www.shoptalkforums.com/viewtopic ... 070#800070

takotruckin · Post by **takotruckin** » Wed May 30, 2007 6:13 pm

at one point, i turned the lights off, and the temp gauge dropped, not sure if it was because i turned the lights off, or just part of the cycling it was doing. i will mess with it further this weekend

takotruckin · Post by **takotruckin** » Sun Jun 03, 2007 6:39 pm

ok, it's definitely a power issue. with the fan and headlights on, the power at the guage drops over a full volt with the engine running. i guess it's time to run some more wire to the front of the car. thanks for the help guys

MNAirHead · Post by **MNAirHead** » Mon Jun 04, 2007 7:07 am

Has your car been tapped into like many of us?

I've learned pulling off all the cheezewad splices and repairing also helps.

takotruckin · Post by **takotruckin** » Mon Jun 04, 2007 5:56 pm

oh, its been tapped into WAY too much. it needs a whole rewire, but im trying to band aid it until i build the new chassis

MNAirHead · Post by **MNAirHead** » Tue Jun 05, 2007 1:14 pm

REally funky thing happened.. I pulled all the little splice connectors off ALL the gremlins went away.