Gauges stopped working Help!!

[04mustang70]

I have a 1970 Mach 1. I had some dash lights out and decided to replace all of them. Went fairly smooth replacing the bulbs. Got the connector and speedo cable back in. Checked to see if the lights all worked and success!! They worked. That was a few weeks ago. It finally got nice here in Southern Wisconsin so I took my car out for its maiden voyage of the year. I noticed my Oil pressure, gas, temp and alt gauges do not work. Does anyone have any suggestions how to go about trouble shooting this problem? Its not the fuse. I checked. Did I forget somthing on reassembly? Thanks for all of your help. It's a pain not knowing how much gas you have!!

 

[iskwezm]

did you fry the IVR??? i fried mine 5 years ago and havent fixed it

 

[04mustang70]

Thats what I'm beginning to think. Has anyone had any experience in changing them? Where can I get one? Can I go to my local Napa and get one? Thanks

 

[bnickel]

i would bet on the IVR too, yes you can get them at your local napa store. they are very easy to change once you have the cluster out, just one screw and then it snaps out like a 9 volt battery.

 

[04mustang70]

I bought a IVR and the gauges still dont work. There all pegged to the left. The IVR I bought was used (shame on me). My question now is how do you go about testing the two IVR's that I have to really see if they are bad? Use a voltmeter? Connect them up to a 12volt power source and measure what there putting out? What should they be putting out? Do they have to be installed to do this? I hope the one I bought is bad and then I would just buy a new one. HELP!!!

 

[chris66dad]

The output of the IVR should be about 5-6 vdc and it will pulse if it is working correctly. If it does not pulse it will be outputting 12 vdc to the gauges causing them to go full scale.
If all the gauges (except Amps) are full scale it is a safe bet the IVR is bad.
You can also make a solid state IVR from radio shack parts and not have this problem again. It will put out a stable 5vdc.

 

[04mustang70]

My gauges do not read full scale when everything is put together. They all read nada (no gas, cold engine, no oil pressure). Could the IVR still be the problem?

 

[chris66dad]

It probably is bad.
It also could be a bad ground for the cluster or IVR.
Try putting a wire from the cluster to a good ground point temporarily to see if they start working. This will test if the ground is bad.
You can pull off the oil pressure sender unit wire by the oil filter (289) and put a voltmeter lead into the connector and the other lead of the meter to a ground with the the scale on 20 VDC. If there is no voltage, the IVR is open and not working or not grounded.
I made a solid state IVR. Here is a "how to" link from my website if your interested.
CLICK HERE ==>IVR

 

[04mustang70]

Thanks for the info. So I can test the IVR from under the hood using the temp sensor wire or the oil pressure sender wire? Anyone else with any advice?