Instrument Voltage Regulator Problem?

[Bronco]

I'm trying to figure out why my gas gauge, temp gauge, and oil pressure gauge are not working. It seemed simple enough, put in a new IVR. So I bought one at Napa the other day expecting that to fix the problem, but that did not work.

When I first had this problem the gas gauge and temp gauge would read on the completely low side, while the oil pressure gauge would read past the high point. After I put the new IVR in they are all just staying at the low end now. I don't know if this means anything or not.

All of the lights on the cluster work. I tried checking all the grounds I could find. I know absolutely nothing about electrical so I may have missed an obvious ground.

There is power coming to the IVR. I hooked up an analog voltage meter on the output of the IVR and I was getting 10 every once in a while. It wasn't really steady on where it would end up. It would end up anywhere between 4 and 10. It bounced every half second or so.

I'm thinking I will try and put another IVR and see if that solves it. But wanted to see if anybody had any other trouble shooting tricks I could try before Napa makes me bend over again for a $60 IVR.

Thanks for your help. This is on a '76.

Aaron

 

[70_Steve]

There is power coming to the IVR. I hooked up an analog voltage meter on the output of the IVR and I was getting 10 every once in a while. It wasn't really steady on where it would end up. It would end up anywhere between 4 and 10. It bounced every half second or so.

That sounds about right. The output of the IVR is a pulsed voltage, kinda like the turn signal flasher, only faster. I would start by checking to see if you have that same pulsed voltage at the sending unit. Just unplug the conector at the sending unit, and measure the voltage between there and the block. For gauges that are functioning normally, unpluging the wire from the sending unit will cause the gauge to go below 0. Shorting the wire to ground will cause the gauge to peg full scale.

I've also read posts about a bad replacement IVR. Still had a pulsed output, just not as fast.

 

[ransil]

Quick check pull of the oil or fuel sender wire, gauge should go to zero, ground the sender wire and the gauge should peg out the other way.
Better test get a 100 ohm potentiometer form radio shack and install it on the end of the wire and you will be able to vary the pot a see the gauge move.

The IVR is grounded thru its case make sure it is grounded good, then make sure what ever it is grounded to is grounded good to and so on and so on.

 

[DirtDonk]

Although your pulsing seems to be at regular intervals, I don't think that erratic voltage reading is correct. Unless it's just that the meter is not able to follow the pulse correctly.
I got a bad one. Read low all the time. But in that case it not only had erratic voltages, but also erratic pulse timing.

I have a new spare because I haven't had the chance to install the new one in my friend's Bronco yet (to replace the previously mentioned bad one).
I'm not sure if I can test it easily in the next couple of days, but maybe someone else is in the middle of a project and has theirs accessible and can measure the output for you. To compare things a bit more.

If NAPA won't take it back, or at least let you test another one somehow(?), try one of Dusty's new electronic IVR's. He's listed in the vendor forum and just posted up that it's on their website.

Paul

 

[Bronco]

Thanks for the help guys. I haven't been able to work on it yet since I sold it to my 16 year old brother last week. At first he complained about the gas gauge not working, now he just wants to drive it and doesn't care. Once he brings it over to my house I'll try all your suggestions.

thanks.

 

[nj_thusar]

A follow through would be awesome. I'm having the same problem. I had a used spare, which worked for a day and now is shot. I've been molesting my truck with a voltmeter for days... ugghh.