Quote:
Originally Posted by cjatx
I've never been able to get the stock temp gauge working right in my car. I replaced the engine harness and the temp sending unit. Prior to starting the car the gauge sits at about 125 degrees. When I start the car, it drops to zero, but in a couple minutes it's at 250 degrees. With the car warmed up, readings at the sending unit with a temp gun show between 175 - 185 degrees. I'm using a 180 degree T-stat.
I'm wondering if I have a bad ground somewhere or a bad gauge. Does anybody have any experience with this?
Thanks,
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It sounds like your sender isn't providing any resistance to ground after the coolant starts to warm up.
Unplug the wire to the sender with the key on, and the gauge needle should drop all the way to cold.
Then, with the wire unplugged and key on, you can touch the wire to ground with the key on,
but that can be very hard on the gauge/needle as it will slam into the stop peg on the high end of the gauge. So, a better solution would be to touch the wire to a 45 ohm resistor that is grounded. Doing this should peg the gauge to the hot side (or come very close) without hurting the gauge.
Probably 99% of all the commercially available sending units from parts stores WILL NOT allow your gauge to read properly. They are designed for lates 70's and later cars, even though the application book says theyll work for rthe 67-74 cars.....they don't and are not accurate. The easiest and cheapest thing you can do is to order a temp sender from these guys:
http://www.lectriclimited.com/mainpage.htm
If your gauge still doesn't work properly, it might be the printed circuit for the gauge (they DO go bad) or the gauge itself.....also not uncommon for a 35-40 year old component. After that about all that's left is the wiring in the dash harness.
Try the easy stuff first.