temp gauge not working?

[dedgar]

So today I drove out to get my new hardtop and noticed my temp gauge doesn't seem to be working. I drove 40 minutes at 70 so I know the engine heated up. When the ignition is off the gauge goes all the way to the left. I turn on the truck and it raises to the just started position and then never moves. It should go up I know but didn't.

Is it the thermostat going bad or the connector? or something else? How can I diagnose it?

I drove the heater at full blast just in case and it was a hot ride.

 

[jw0747]

temp sensor...

 

[B RON CO]

Hi, to test the gauge, you unplug the wire at the temp sensor on the engine and momentarily ground the wire. If the gauge is working properly the needle will go full sweep to hot, and return to cold when you remove the jumper from ground. You can test all your factory gauges this way. Good luck

 

[dedgar]

Hi, to test the gauge, you unplug the wire at the temp sensor on the engine and momentarily ground the wire. If the gauge is working properly the needle will go full sweep to hot, and return to cold when you remove the jumper from ground. You can test all your factory gauges this way. Good luck

so that would be with with ignition to on (not engine), then use another wire to stick in the temp sensor female end and touch it to the engine block? and see if the gauge moves?

 

[B RON CO]

Hi, yes, key on, ground sensor wire. Gauge goes full sweep. You are testing factory gauge in dash, correct?
If you have a digital thermometer you can check the temp at the thermostat housing. If the thermostat is stuck open the engine may not reach operating temp, otherwise put your hand on the upper hose. It should be too hot to hold for long. Good luck

 

[dedgar]

Hi, yes, key on, ground sensor wire. Gauge goes full sweep. You are testing factory gauge in dash, correct?
If you have a digital thermometer you can check the temp at the thermostat housing. If the thermostat is stuck open the engine may not reach operating temp, otherwise put your hand on the upper hose. It should be too hot to hold for long. Good luck

Yes all 1970 parts. I turned the ignition to on, put a wire up the sensor and touched the engine block. My wife sat inside to watch and said nothing moved. I think a bad thermostat would be easier to replace.

Any other tests or have I figured it out.

 

[B RON CO]

Hi, do the fuel and oil gauges work? The gauges (except amp gauge) are powered by the same instrument cluster voltage regulator.
Check the temp sender wire for damage, and gently scrape or clean the plug end. If you cannot get the gauge to move by grounding the sender wire, the trouble is probably in the gauge or the wire to the sender. You have to get behind the dash to check the gauge and wires. Good luck

 

[B RON CO]

Hi, you said you put a wire to the sensor and touched the block. The test is to ground the sensor (sender) wire, not the part that is screwed into the block! Momentarily ground the wire and see what happens (key on). Good luck

 

[dedgar]

So I tested it one more time and the sensor wire just snapped off about 7 inches in. So I'm guessing the wire was frayed under the tape and will just need a new wire. But it sounds complicated.

 

[B RON CO]

Hi, this could be an easy fix. Follow the wire back past the damaged hardened area and cut the bad part out. Next try the grounding test. If the gauge goes full sweep, just splice in a new section to the sender and maybe attach it to the sender with a loop terminal and nut. Good luck

 

[dedgar]

Okay turns out it was the temp gauge. Had to fix the wire though. I bought one from Autozone and it doesn't really tighten down as much as the original? It's really snug so I don't think it will pop out. I don't see any leaks so far. Is there a better one out there?

 

[Slowleak]

Dedgar, Did you mean that you replaced the sending unit?

Different years need different senders. If you get the wrong one, you gauge reading my be off. My ‘77 needed a TS58T to be accurate.

This thread may help. It has the senders for a ‘70.
http://classicbroncos.com/forums/showthread.php?t=202857

 

[dedgar]

Dedgar, Did you mean that you replaced the sending unit?

Different years need different senders. If you get the wrong one, you gauge reading my be off. My ‘77 needed a TS58T to be accurate.

This thread may help. It has the senders for a ‘70.
http://classicbroncos.com/forums/showthread.php?t=202857

i just replaced the sensor

 

[Slowleak]

i just replaced the sensor

If it doesn’t fit right, doesn’t look like the old one, or the temp isn’t reading accurately, then they may have sold you the wrong one. Check the thread in my earlier post for the part numbers.