Oil and temp gauges died at once?

[AMXguy]

I did some detailing under the hood but never messed with the wiring but my rally gauges for oil and temp don't work at all . they're fresh rebuilt and worked great until now. any ideas where to look? all the fuses are good but I don't know where they get their power from or where to start.

[GoodysGotaCuda]

How is the battery > engine ground? Whip out the 'ol test light too and see if your getting a 'pulse' of power to the sender wires with the key on.

[Chryco Psycho]

the voltage regulater is on the back of the guages & pulses 5-6 V to the guages but it feeds the fuel guage as well so the problem could be the connections at the firewall plug , the fuel gauge doesn`t go through the firewall plug

[basement]

I agree. Nearly all of my electrical problems have been traced to the passthrough connector on the firewall. All of the years of chemicals and heat make that connector very brittle.

[AMXguy]

I'll test the sender wires, 5-6 volts? it could be in the plug in area as I put a new wiper motor on and maybe I moved something there.  thanks guys

[AMXguy]

Ok no power to the sender, the firewall plug ins look good and clean and I moved them all around but still nothing. fuel gauge is working , does it have to be the plug in ?  any other ideas?

[Chryco Psycho]

power goes from the voltage regulator on the dash to the guage & to the sender to ground so you need to trace it back to where you have power , it could definatly still be the firewall plug if the connectors are loose

[AMXguy]

 nothing on the inside of the firewall either, so it must be the regulator or a connection there.  isn't that on the back of the cluster? 

[Chryco Psycho]

yes

[Bullitt-]

If it were the voltage limiter on the gauges the fuel gauge would be affected too. I think it just about has to be in the wiring.

[Moparal]

Maybe check your steering column plug. Sometimes it will unplug half way when it's been tampered with.

[MEK-Dangerfield]

nothing on the inside of the firewall either, so it must be the regulator or a connection there.  isn't that on the back of the cluster? 

The thing is, this same regulator feeds your gas gauge, so it is apparently working.   Are you trying to measure the voltages between sending unit wire and ground? You would have to do this with the key in the "on" position.


  Mike

[AMXguy]

  I tried it from several place on the sender wire to ground and with the key on and I can't get juice anywhere. are you sure the gas gauge feeds off the same regulator?  a friend is a B body guy and he says the gas gauge has it's own power separate from the oil/temp and he's run into this before. maybe they're different?

[Bullitt-]

E-bodys use 1-voltage limiter.
I just ran a test on mine to see what should happen. Using a digital mutimeter set to DCVolts on the 20V scale & ignition ON motor cold & not running, pulled the temp. sensor wire, inserted  + lead to wire - lead to sensor terminal. Meter flashed 4.XX then 0.00 then 3.XX then 0.00 numbers continually. Got the same results with - lead to ground.  The voltage limiter oscillates on & off so the 0.00 readings are when its open. 

[Chryco Psycho]

all 3 guages are powered from the regulator with a triple connecter wire