Bad temp gauge

[Tannerm]

Been trolling this site, and others, but couldn't find my answer. So I signed up.

1996 XLT 5.0 63K miles
-Replaced the sender unit (the gauge one, not the ecu sensor).
-does not overheat.
-heater blows HOT.
-tstat is 10-4

The gauge has the needle pegged below C. Common issue I know. But if I try to ground the wire to the sender, it's supposed to peg the temp gauge at H. Mine does not. So, I got a cluster or wiring issue. I took the cluster out and inspected the back. Then I took of the front cover and pulled the temp/fuel gauges. Nothing seems amiss there. Now, if I move the temp gauge needle by hand, plug the cluster back in, and hit the ignition to ON, the needle drops back below C.

I'm about to buy a replacement temp/fuel cluster off eBay (I hate aftermarket gauges... look shotty). I'm curious if there is something I'm missing.

 

[koda2000]

Only other thing I can think of is to test for continuity on the sender wire.

 

[Tannerm]

Elaborate. Not a big electrical guy. Actuality, I hate electrical stuff.

 

[koda2000]

Elaborate. Not a big electrical guy. Actuality, I hate electrical stuff.

Really quite easy to do with some sort of continuity tester. Think of the sender wire from the sender to the gauge as a water hose. You need to make sure water/electricity flows from one end of the hose to the other. My volt/ohm meter (VOM) has a continuity test setting, but there are also less expensive devices that light up if there is continuity. I find owning a good quality VOM is a very useful tool.

 

[Tannerm]

And what does this prove that grounding the same wire doesn't? U gotta forgive my ignorance. I don't have a voltmeter but could eventually get one. I'm not too rushed to fix it since she doesn't run hot or overheat. I wish this issue was engine related... I know these Windsors like the back of my hand. Dang

 

[Tannerm]

Hell, I guess I could pull the cluster and swap it with my wife's 99 expl... that would definitely tell me that the gauge is kapputt!

 

[koda2000]

And what does this prove that grounding the same wire doesn't? U gotta forgive my ignorance. I don't have a voltmeter but could eventually get one. I'm not too rushed to fix it since she doesn't run hot or overheat. I wish this issue was engine related... I know these Windsors like the back of my hand. Dang

It would prove the sender wire is good or bad. If the wire's good then the gauge must be bad. With a VOM you could have also tested the sender to see if it was working by measuring the resistance as the engine warmed up.

I guess if you have a lot of time on your hands you could try swapping in the cluster from your other truck, but in addition to the time you'll spend you run the risk of damaging something on the truck that was working fine. For example, the shift cable for the PRNDL display is easily broken.

BTW, if your going to remove gauge clusters, do yourself a favor and replace the six #194 gauge illumination bulbs with Long Life bulbs.

 

[Tannerm]

Ok thank you. I appreciate your help. It's about time I got a VOM anyways.

 

[koda2000]

Ok thank you. I appreciate your help. It's about time I got a VOM anyways.

It's a great tool to have. I use mine all the time, whether on vehicles, appliances or anything electrical. Mine is a Craftsman digital meter that measures AC or DC volts, Amps, Ohms, continuity and even has a temperature probe, is auto-ranging and has more functions I've never even used. I paid around $70-$80 for mine over 10 years ago. It has saved me a lot of time and money over the years, paying for itself many times over. One thing it does for me is that I never buy sensors and other automotive electrical components needlessly, as I can test them first.

You can get something that will work for around $20-$25 and you can spend over $100.