70 Rallye dash voltage limiter

[70GETEX]

I have a 70 GTX that non of the gauges work. I pulled the cluster out of the dash and checked the voltage on the voltage limiter. I put 12V on the power side and was getting full voltage on the terminal that should be 5V that feeds all of the gauges. I assume I need a new voltage limiter but what about the gauges? What happens to them when the get full voltage instead of 5V do they just not work or does it smoke them?

thanks

 

[steve817]

Depends how long the gauges were exposed to the 12v's. I would assume that the gauges are not working because the high volts fried the elements. Do not get rid of the gauges as they may be restored, especially if the gauge faces/needles,cans are in good usable condition. Put a solid state voltage limiter in place of the original one. It provides a constant 5 volts to the gauges and is reliable. I get mine from charger specialties. You can also find them on ebay for about 60 bucks. Well worth it! Pm me if you are interested in sending me your complete gauge cluster for restoration. Hope this helps, Steve

 

[Grabinov911]

Het GetEX check out this thread: http://www.forbbodiesonly.com/moparforum/showthread.php?32770-Temp-Gauge-Temperature-Gauge

It'll tell you all about testing gauges and voltage limiters. In my experience folks are quick to believe that the gauges have been fried due to exposure to 12 volts, but they are really not THAT sensitive. In addition it is complicated to test the stock voltage limiter (or many others for that matter) due to the fact that the voltage "pulses" up and down between 0 and 12 volts - in other words they effectively limit the voltage to an AVERAGE of 5 volts. On a voltmeter you'll see 12 volts, then 0, then 12, etc. The best way to test the limiter is with a test light - watch it pulse and you'll know the limiter is working.

Hook up 4 double A batteries (or four C's, etc.) in series and hook that to your gauge to see if it works. It'll go all the way to HIGH (full, high, top, whatever) but since it's only being fed 6 volts, it won't be harmed in any way. This will obviously not work on the ammeter as that is a totally different type of gauge (the scary dangerous type - just unhook it). Make sure to power the gauge directly, and not through the sender, as the sender (fuel, temp, oil pressure) is a variable resistor and will further limit the voltage.

Sorry for the ramble. I love this stuff. Send me your questions LOL...

 

[70GETEX]

Good info guys. I will do some more research tonight and see if I can determine if the voltage limiter is actually working or if it's cooked and the same for the gauges. Steve, the gauges are certainly restorable as they look almost new. thanks for the help!

 

[70GETEX]

Ok, I went home over lunch and put 12 volts to the VL and put the test light on the 5V side. Light stays bright and does not pulse like it should so it looks like I need to start with a new VL and tonight I will do some more checking on the gauges!

 

[A383Wing]

Ok, I went home over lunch and put 12 volts to the VL and put the test light on the 5V side. Light stays bright and does not pulse like it should so it looks like I need to start with a new VL and tonight I will do some more checking on the gauges!

did you connect the ground side of battery to the limiter body before testing?

Bryan

 

[300]

Disconnect condenser for radio and see if gauges work

 

[70GETEX]

did you connect the ground side of battery to the limiter body before testing?

Bryan

Yes, it grounded it to the limiter body, still get 12v!

- - - Updated - - -

Disconnect condenser for radio and see if gauges work

I went one further and pulled the gauges out of the cluster and put 6V across them one by one and none of them wiggled. I ohmed each one and they all were open. So from this I think I need all new gauges and a new voltage limiter (solid state) so I ordered the VL from RTE as I bought a tach and clock kit from them for my Cuda and they worked great. Now where should I get the new gauges? I might upgrade the dead clock to a tic tock tach since I have the cluster out and all of the wiring exposed it would be a good time to upgrade that as well. It looks like the only thing that works is the speedo.