Since I bought my truck, the instument cluster gauges max out when I turn the key on. Over the last couple of days, I have torn out the wiring harness in the cab and looked it over. I also took the ground wires and put them into a new area that I sanded down. I have replaced the regulator on the back of the instrument cluster. I still have the same problem and was wondering what else could be wrong. Would a missing ground strap from the motor cause this problem?

 

Doing a continuity test between the battery ground and instrument panel ground would verify the ground is ok or not.

 

Go out the engine. Find the oil pressure sensor wire(it will probably be red/white or white/red) and turn the key on but don't start the engine, and take the sensor wire and ground it to the engine block, and then unground it. Your oil pressure gauge should swing back and forth when you do this.

You can test the engine temp guage the same way, it will have the opposite color of the oil sensor wire(red/white or white red) and see if it swings back and forth.

If they swing full scale back and forth, the guage and the wiring are good, and there is something wrong with the sensors.

 

Thanks for the info. I already tried the ground test for the instument cluster but not the wires off of the sensors yet. thanks. Also do you guys know what the small silver box is that is close to the silinoid switch, on the passenger side. I know its not the egnition box. I believe that it has 3 wires to it and 2 of them are yellow.

 

You've only said the vehicle is a '76 yr model. What are you working on 'exactly'? -- F150, F350?... 300 I6? --V8? -- or maybe a diesel? --- need more info.

 

His profile says '76 250.

 

ahh so it does. ~ my mistake. -- but that doesn't provide very much more info really.
-- especially with respect to certain types of electrical issues (in my experience).

 

Sounds like you're referring to an external voltage regulator.

 

A photo would help....

 

Sorry - site double-posted

 

The silver box does sound like the voltage regulator. The 2 yellow wires will go to the "A" terminal, a red/green going to the "s" terminal and a orange going to the "f" terminal.

 

I know that my voltage regulator has a blue top it. The a silver box that I am talking abou is about 1/3 the size of the voltage regulator. It is located on the passeger side. The battery is first then the siliniod, then a little silver box that measures about 1.5"x 1.5"x3". I do appreciate the help. Sorry I can not post pictures yet.

 

I think if you use PhotoBucket you can....A PhotoBucket account is free.

 

1976/79 F100/350, 1976/80 Econoline and 1978/79 Bronco came with instrument cluster backs made from a composition material that can TURN TO DUST before your very eyes!

There are two types, with or without oil/amp gauges. This also applies to the printed circuit board.

1981: Ford came out with hard plastic cluster backs. Were installed in Econolines and were the service part replacements for the POS composition cluster backs.

Some were replaced under warranty, some by owners, but some were never replaced.

E1PZ-10848-A .. Cluster Back-Use with Oil/Amp Gauges: 1981/91 Econoline. Service part replacement: 1976/79 F100/350 / 1976/80 Econoline / 1978/79 Bronco.

E1PZ-10848-B .. Cluster Back-Use with Oil/Amp Warning Lights: 1981/86 Econoline. Service part replacement: 1976/79 F100/350 / 1976/80 Econoline / 1978/79 Bronco.

Dennis Carpenter has over 500 NOS E1PZ-10848-A / About 100 of E1PZ-19848-B / 800-476-9653.
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D1AZ-10804-A .. ICVR ~ Instrument Cluster Voltage Regulator-attaches to printed circuit board (Motorcraft GR-513)

When this litle charmer begins to fail, the temp and fuel gauge needles sometimes do "the hula" swing wildly back/forth on their own. When it fails, the needles peg.

ALL: 1971/86 F100/350 & Bronco / 1971/91 Econoline.

Note: With an oil pressure gauge, the sending unit is different than with an oil warning lamp.

 

Thank you. I did some more testing and one of my fusable links comming from the altenator was hitting 15 volts briefly. If that is the case and the regulator behind the cluster had been hit with that kind of voltage, would that cause the regulator on the cluster go bad.