3rg Gen Rallye Dash Fuel and Oil Pres. Gauge Dont Work

[bordin34]

Does anybody know why they wouldnt work. They dont even quiver when I turn the car on. Do they have a fusible link? Every other gauge works.
Thanks,
Dan

[moparguy01]

check the fuel guage. Go under the car and check for power at the sending unit. if not theres a distinct possibility that you blew what is called the instrument cluster voltage regulator. but usually when you blow that all the guages go screwy.

[bordin34]

Where is this power sending unit and what does it look like?

[Charger1973]

Its the blue wire that comes up through the trunk floor and into your wiring harness.

[moparguy01]

    

just find the wire and check for any power. key on naturally.

[Charger1973]

   

just find the wire and check for any power. key on naturally.

[bordin34]

I think that the entire gauage isnt getting any power because the oil pressure gauge doesnt work either.

[bordin34]

OK the fuel gauge is getting power it goes from the left of E to E when i turn the car on. Where does the power for the oil pressure gauge come from. It sounds like it is getting oil pressure and idle smooth once warm.

[moparguy01]

i bet its the instrument cluster voltage regulator then. I remember when mine went out i almost crapped myself. Imagine driving down the highway around 100 mph then every guage except the speedo starts bouncing and drops off like it was pushed off a cliff.

Not sure if you can still buy the limiter at parts stores, but its worth a look.

[Nacho-RT74]

if voltage limiter gets damaged then oil/temp/gas gauges stop to work at the same time.

Rallye gauges get power on any position, including accesories.

Source from sender is purelly grounds, with variable resistors to send the level to propper gauge.

Voltage limiter gets power from fuse box, on accesories side.

Standart cluster gets power just on RUN position and START when throught ballast the power is coming back.

[bordin34]

My temp gauage works fine so I guess thats not it.

[Nacho-RT74]

try to direct ground the gauges on stud to check if you get full scale... ( the colored plug side )

[Paul G]

Would your temp gauge be reading lower than normal? It is comman for the instrument voltage regulator to be outputting a low voltage. It should be around 5 volts. Easiest way to measure it is to put a volt meter between the wire that goes to the temp sending unit and ground. You want 5 volts. The factory regulator is a pulsed output. Really crappy way to do it. Measure it there on the DC scale and tell us what you get.

It is possible to have a bad ground at the sending unit on the tank, and have a bad oil pressure sender too. 

try to direct ground the gauges on stud to check if you get full scale... ( the colored plug side )

Lift the wire at the oil pressure sending unit and ground it. Your oil pressure gauge should read full scale and pegged. Do the same to the wire for the fuel sender if you can access it.

[Nacho-RT74]

try to direct ground the gauges on stud to check if you get full scale... ( the colored plug side )

Lift the wire at the oil pressure sending unit and ground it. Your oil pressure gauge should read full scale and pegged. Do the same to the wire for the fuel sender if you can access it.

I'm talking directly on gauge stud to discard the gauge once what is the worse it could happen and then if get read search on wiring up to sender