IVR pulse at 4 volts gauges read low

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nm9stheham

That pic I posted may not even be an a-body Ralley gauge.

It was taken from RTE's website. It is shown there as an example for disabling the IVR under the A-Body section. I added the large arrows based upon the stud posistion's of an a-body gauge.

Wish I had one in my hand to look at.

Cannucky says Ben knows the proceedure but I can not find it online anywhere. Hopefully he will add some good solid info. I only want to do this once no matter the proceedure and would really like to understand exactly what I see and how it is corrected the best way. Seems there are several people selling product to remedy it. Kinda got the feeling he does not approve of RTE. If that is true, seems he would lay out a good case as to why the demonivr and his proceedure is better. He may have done this before but my attention span gets short when using the search feature here.

Anyhow I will wait to go further until my scope gets back.
 
Wow; a zillion responses. Here is my final input. If your IVR is bad and the instruments are, in fact, reading low, you will have to pull the instrument cluster regardless. You will either have to pull the gas gauge to have the built in IVR fixed, or to bypass the gas gauge IVR with a digital one (remember the link to D&M). I see no way to fix your problem without pulling the instrument panel.
 
1969383S said:
nm9stheham

That pic I posted may not even be an a-body Ralley gauge.

It was taken from RTE's website. It is shown there as an example for disabling the IVR under the A-Body section. I added the large arrows based upon the stud posistion's of an a-body gauge.

Wish I had one in my hand to look at.

Cannucky says Ben knows the proceedure but I can not find it online anywhere. Hopefully he will add some good solid info. I only want to do this once no matter the proceedure and would really like to understand exactly what I see and how it is corrected the best way. Seems there are several people selling product to remedy it. Kinda got the feeling he does not approve of RTE. If that is true, seems he would lay out a good case as to why the demonivr and his proceedure is better. He may have done this before but my attention span gets short when using the search feature here.

Anyhow I will wait to go further until my scope gets back.
Click to expand...

pm sent
 
In the beginning, Every vehicle operated on a 6 volt electrical system. All of the components were designed to that 6 volts. When 12 volt systems brought brighter lighting, etc.. a few design changes in components were required.
In the case of thermal gauges, GM was the only mfgr of that time to redesign those instruments so they operated on the 12 volts. Every other mfgr opted for a mechanical voltage limiter. This added component would take in the 12 volts and put out a intermittent or pulse voltage. A bouncing set of contacts may sound crude by todays standards but.. this thing did work very well for a very long time. If it received close to a steady 12 volts it would release approx' 6 volts. Therefore nothing else about the thermal gauges would need redesign. They would work just as they did in the 6 volts systems ( just range indicators afterall ).
What did matter and what didn't matter;
Where the mechanical limiter is located didn't.
The voltage supplied to it and a zero resistance path to chassis ground from it does matter.
Is this owners mechanical limiter simply worn out ? Maybe. it is nearly 50 years old.
Is there a way to test it and/or adjust it so it works right again ? Maybe.
Is replacing it with a solid state regulator that releases a steady voltage the better route ? Of course. For several reasons including extending the life of those thermal instruments that are also nearly 50 years old.
 
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