Why is my temp Gauge pegged on high? (1 Viewer)

[twoturtlesracing]

Hello Guys,

So last week I pulled apart my gauge cluster apart to clean it up and do the light shields mod, then put it back together the way it came apart. I also pulled the headlight switch out to repair the broken rheostat for my dimmer switch (I had to solder one of the rheostat loops because it was broken near the bright end.) Both, I have put together just the way that I took them apart. But now, my temperature gauge is pegging on high, and my fuel gauge may or may not be pegging also. (Can't remember how much I've driven since I put fuel in it) My ammeter and oil pressure seem to be working fine though. Everything worked just fine before I pulled them apart, so I really rather doubt something went bad... I've pulled everything out to double check... Haven't seen anything out of order... Felt the engine to see how hot it was, warm, but not more than normal, (In fact it was cool, I could stick my finger in the coolant.) I had just started it, it ran for about 3 minutes when it started climbing and now climbs every time I turn the key on. The thermostat is new as is the temp sensor. ( I also knocked on the thermostat housing in case it was stuck)

Any thoughts? I am wanting to put my on new Alcan lift, not be tearing apart stuff I should be done with!

Thanks for the input Guys!

 

[Trollhole]

Your grounding the temp sensor to the housing of the cluster. Check for continuity between the cluster case and the terminals of the sending unit.

Don't fix it and you will burn the gauges out.

Take the cluster out and run continuity.

 

[twoturtlesracing]

Thanks TrollHole. I will go put the ohmmeter on it right now. Thanks!

 

[twoturtlesracing]

!

So let me make sure that I'm doing this correctly... I hooked one lead to the cluster housing. (One of the screws that hold the guage panel into the housing to be precise.) And the other lead onto the temperature sensor. I am showing continuity between these two... That should not be there correct?

Thanks!

 

[Texican]

Correct

the fuel and temp gauges work via ground coming from the senders, for instance an easy test on both is to unhook them from the sender, key on, ground them, the needle should peg to hot or full

 

[twoturtlesracing]

So I tried that... Yep, the temp goes up to hot... Trying the fuel... pzzzzppptt! Oh shoot! I don't think that was supposed to do that...

It sparked and made a little bubble in the PCB. I still have continuity through the fuel gauge though. (That means that It's still good right?)

I am not knowledgeable enough to know for sure what that means. Does it mean that my problem is somewhere in the fuel gauge circuit? Or is it still a problem in the gauge cluster? And if so, where should I start looking? The "gasket" between housing and gauges is still there... But with the screws holding them together, their should be continuity there anyway right? So I must have a short somewhere?

Am I thinking along the right lines?

 

[Alaskan_IB]

Back when I was younger I also had a ground issue with the temperature sensor. This was of course for a 1975 F-250. In the intern I fixed the problem only to notice my fuel gauge was not working at all. So being young and dumb not realizing that the fuel sensor or sending unit works off resistance I hooked up the battery right to it. Needless to say I am surprised to this day that I didn't blow myself up because the sending unit was in the fuel tank behind my seat in the cab. The only thing that saved me (besides God) was the fact that the sending unit wasn't in the fumes but in the gas.

Robert

 

[twoturtlesracing]

So any common places I should start looking? And I should be looking for a short in the wiring somewhere? I'm a little confused. And why, when I went to ground the fuel guage did it spark? And what does that mean? Sorry to be rather ignorant on the subject, but there is only one way to learn right? Thanks for the help guys!

And Alaskan IB, God takes care of fools and little children doesn't He? Sometimes it's a combination of both! I think that I was ok, as the hot wire was disconected. ( Not sure if that's right yet..)

 

[Texican]

Do ya have a wiring diagram for this rig?
Know how to read one?

If not get one and follow the path, my guess is that you have something on the cluster either wrong or grounded.

 

[twoturtlesracing]

Texican,

I do have a wiring diagram for my rig, thankyou. And as far as having something wired wrong, I don't think that is possible. The only wires that I connected or disconnected are where the factory harness plugs into the PCB, and it can only go back in one way... No other wires to connect or disconnect.

I'm thinking that I must have an intermittent short somewhere in the wire between the sensor and gauge is all I can figure, because I plugged it back in this morning and it is working right so far. As soon as I finish putting my lift on, I'll go drive it and see if it acts up again.

 

[Texican]

You can break or pinch the circuit board on the back of the cluster, all those little copper lines in the board.......transmit voltage.......

Butch

 

[twoturtlesracing]

Yeah, that makes sense, but I have looked for cracks, etc and haven't found any. The only damage to it was, regrettably, from when I attempted to ground out the fuel guage last night as you mentioned in an earlier post, and it blew the circuit for the fuel gauge. (I still don't understand why that happened, any thoughts?) I actually had to run a wire to bypass the blown circuit as it looks to be to delicate of a spot to try to and solder. A good fix, just not factory.

 

[Trollhole]

If you loosen the terminals holding the gauge on the back of the pcb board and don't get them centered correctly you can ground out the terminal on the side of the gauge metal mouting plate. There are insulators that should help prevent them. Assuming they are on correctly.

 

[twoturtlesracing]

Thanks TrollHole,

I've been wondering about that. I will look specifically for that if I still have a problem. Thanks for your patient answers! And btw, are you going to post more vids of the big gay? I think that several of us would enjoy some of it being wheeled!

 

[twoturtlesracing]

Well, I don't know if I had a washer that wasn't centered on the back of the pcb- that aligned itself when I took it back apart- or what, but I don't seem to be having any issues since I finally got my lift on and was able to drive it around. I appreciate all the input guys. Gotta love 'Mud! to all!

 

[Hugh Heifer]

When I saw this I was dying to say two worthless things:

Your engine is running hot.

Your Gauge is broken.

Sorry. Had to.