need some help on my gauges

[rnjump]

  I am really in the dark when it comes to the electrical on these cars so bear with me. All the gauges are pegged and I need some place to start looking. I assume I should start looking for a grounding problem. Is there something I should look for on the circuit board. Any help on where to start? Thanks

[Back N Black]

Sounds like you need a new Voltage limiter, the cluster is getting a full 12 volts and is causing the gauges to peg. The Voltage limiter is located on the back of the cluster, two prongs, silver thingy.

[billschroeder5842]

See if you can find a transistorized (?) one. That way you never have to worry about having the mechanical arm fail and burning your guages.

[rnjump]

  i have since heard the same thing about the limiter. Thanks for the picture, it will help.

[vick79]

One way to check limiter without pulling the cluster is to unplug the coolant temp sensor plug, use a multimeter to check voltage at the plug, should read around 5Volts. If not you have a bad voltage limiter. This is easy to replace with a 7805 voltage regulator chip, a quick Google search will show you how to fab one for less than $10. Keep in mind bad limiters can cause gauges to receive full 12V which could fry your 3 gauges.

First do test above, replace limiter if needed. Then To test the gauge, get a short piece of wire, and ground the coolant temp sensor plug with the wire. Get in the car switch Sign to Acc  but don't start. The gauge should slowly start to swing all the way to the right (HOT), turn Ign off before needle reaches the max to avoid damage to gauge.

It could also be a combination of a number of faults all overlapping symptoms (very common). A lot goes wrong with 40yr old wires. Best way to tackle it is with a fair understanding of electronics, otherwise its quite puzzling. If you know how to work a multimeter your fine, if not I would look into professional restoring your dash.