stock guages problem

[68rustbucket]

I installed a 73 wiring harness and dash from my parts bronco into my 68 rebuild project. After firing up the rebuilt 289, I had max readings on all of my guages, except ammeter. After a trip to the local NAPA, bought and installed a new guage cluster voltage regulator. Now I can only get the fuel guage to read 1/2 a tank, oil pressure will only read 10 PSI, and the temp guage never leaves C. I have 13.5 volt on the black/green wire coming into the voltage regulator, and a pulsating 5-8 volts leaving the regulator. Is this the correct voltage in and out of the regulator? I have replaced the wiring harness to the engine compartment, the oil pressure and water temp sending unit, coil, and fuel tank sending unit during the rebuild. Any help would be appreciated, I would rather use my stock guages.

 

[Broncoholics]

I wonder if the differnet years have somthing to do with it. You can get the painless wiring kit that makes for an easy install and upgrades the fuse block and all.

 

[68rustbucket]

I think I will swap out the guages from the 68 dash and see if that works. I'd hate to change out the wiring harness. It is in very good shape, no splices or piece outs.

 

[beaubear]

I don't think it has anything to do with the year of the vehicle or changing guages or the wiring harness because I have the same exact problem with my 77 and it started while I was driving down the highway. The symptoms at first were that all of my guages pegged to the right and after trouble shooting the problem I came to the same conclusion as you, the instument cluster voltage regulator. I swithed it with a new one and now have the same symptoms as you, I get low readings on everything. I've tried two different regulators because I thought it might be a bad one the first time but that is not the case. I haven't been able to come up with a good reason for it so if you or anybody has a solution I would like to hear about it.

 

[Bully Bob]

It's poss. the gages were damaged when they "pegged" (meaning they had 12v thru them for an extended period of time.

A known "good" gage installed could prove this... i.e. if a diff. fuel gage is installed & reads correctly, chances are the other two are faulty as well.

Did you test the old reg. to see if it was 12v in & 12v out ? (should be approx. 6v as stated above)

 

[68rustbucket]

It's poss. the gages were damaged when they "pegged"  (meaning they had 12v thru them for an extended period of time.A known "good" gage installed could prove this... i.e. if a diff. fuel gage is installed & reads correctly, chances are the other two are faulty as well.

Did you test the old reg. to see if it was 12v in & 12v out ?  (should be approx. 6v  as stated above)

20797[/snapback]

​

Thanks for the reply. I haven't changed out the gauges yet, it is next on my bronco chore list!

 

[beaubear]

I didn't see anything more about the guage problem and since the indications in my guages are exactly the same as yours I am curious if you found an answer. I've already purchased two of the instrument cluster regulator and it's not solving the problem and I can't imagine that all of my gauges are bad although I guess it's possible since it started with my original regulator shorting and all of my guages getting 12 volts+.

 

[Seabronc]

My EVTM says the following about all gages being erratic , High or Low.

Check engine to body ground. ( On my truck, that is a ground strap from the back of the engine to the firewall).

Check instrument voltage regulator ground.

Check voltage to the Voltage regulator.

The output of the voltage regulator is approximately 5V.

The attached diagrams are from the 1983 EVTM but I believe that the circuit is the same for your truck.

Good luck,

>-

 

[Broncoholics]

Good point, I never had a ground strap from engine to firewall. When I added one the truck ran like a million bucks. Ha, and I thought I had a low idle miss... Always check your grounds!