Guages going crazy!

[RECHRGD]

While buzzing along at 70mph yesterday I saw all of my dash guages heading to the  + side (not sure about the ammeter).  My gas, temperature, and oil pressure all went up in unison.  They didn't peg and they went right back down to where they should have been in a couple of seconds.  I saw this happen two times and then it seemed to stop.  The rest of the 70 mile ride home was uneventful.  My voltage regulator is only on its second year, but it's the old style mechanical type.  I'm guessing I should go to an electronic unit, but maybe that's not even the problem.  Any ideas?  Thanks, Bob

[John_Kunkel]

The problem is most likely the Instrument Voltage Regulator (IVR) under the dash, if it fails and sends full battery voltage to the gauges they will read high.

[johntpr]

also check for bad grounds to instrumnet cluster

[8WHEELER]

My chargers have been doing that off and on for 28yrs, I change out the dash regulator and it will not
do it for a year. Then it will start again, but only one time about every third time its driven. If it does
it several times in one drive I would replace it, you can buy brand new ones that are bad 

Dan

[roger01]

you sure can ....i bought 2 that were bad

[RECHRGD]

Thanks for the input guys.  I assume I would need to pull out the dash cluster to change the thing out.  I think I'll wait until winter to deal with it as long as I'm not looking at a potential safety (fire) problem.  I do remember that the same thing happened a couple of years ago and just went away, so I forgot about it.    Bob

[Ghoste]

Well, if it pegs out long enough you can burn out your guages so that might be something you want to consider as well.  You shouldn't have to pull the cluster to get at the thing though.  You may have to do a few contortionist exercises to reach it but it should be on the back of the cluster.

[hulter]

The other thing thtat can do it is short from lamp pin to the gauges within cluster.  There are 2 voltage input pins to cluster.  ONe is 12v and on with key.  The other is the output of the dimmer rheostat- if there is short in the traces carrying the lamp volts in the cluster to the gauge, then guage jumps to right.
I have this problem now and need to find co that do bench testing with 12 volts to both pins while looking at guages for stability to prove the short is fixed.

[NHCharger]

I had the same problem with my 71 Charger. Lucky for me I had no radio in the dash at the time and reached through the radio opening in the dash and wiggled the IVR. Apparently it wasn't getting a good ground on the back of the cluster. Haven't had a problem since.

[BronzeOnSteelies]

I have had similar problems with the gauges. A new IVR did not do the trick.

I have pulled the instrument cluster and found one wire loose. It is from a little condenser mounted on a bracket on the back of the instrument cluster. Its physical location is behind the temp gauge.

Do you guys know where the black wire  with a male terminal is supposed to connect? It is just running out the end of the condenser and is unconnected. My car is a 68 R/T

[hulter]

Yes I have new IVR/volltage limiter and it is in tight.  You can buy them at any Napa store (part no- IR9, ~$20).  My car is regular 68 charger and did not have the condenser behind the temp gauge- don't know what it does.  Mine has an unused female single wire in that postion that goes to the harness- I have assumed that it would be for the condenser on cars so equipped.

Still looking for shop that can bench test all of this under real world conditions.  Autoinstruments Inc can't test this with voltage on bench.

[70daytonaclone]

on my 70 dash gages that condensor black wire goes under the center IVR pin. and has a small piece of thin cardboard (paper) over the IVR pin.

[BronzeOnSteelies]

Thanks guys that info helps.

Hulter, I have a unused female brown connector to the harness also. It is in addition to the wire from the condenser.

70dclone, do you have a part number on that cardboard   

That location under the center pin is what I needed to know

[hulter]

I was told by a gauge rebuilder tht the condenser is for radio interference suppression - to counteract the oscillation signal from the crude electronics of the voltage limiter.  Redline sells a voltage limiter that is solid state -obviates concern and supposedly gives a tighter voltage output.

[smokinrt]

While buzzing along at 70mph yesterday I saw all of my dash guages heading to the  + side (not sure about the ammeter).  My gas, temperature, and oil pressure all went up in unison.  They didn't peg and they went right back down to where they should have been in a couple of seconds.  I saw this happen two times and then it seemed to stop.  The rest of the 70 mile ride home was uneventful.  My voltage regulator is only on its second year, but it's the old style mechanical type.  I'm guessing I should go to an electronic unit, but maybe that's not even the problem.  Any ideas?  Thanks, Bob

OK;  Looked up your guage problem in the service manual.  Dump your voltage limiter switch, get a new one.  You can buy them a little cheaper at YEAR ONE versus the Chrysler dealer.  good luck.  Only other problem is that the guage cluster isn't grounded well, tighten up cluster screws.

Smokinrt

[hulter]

Re comment from rechrgd 0n gauge swingiing to right, I agree it is likely the volt limiter putting out more than its designated 5v.  I suggest that you not install a stock limiter but use the more accurate and durable solid state item described here.    http://www.allpar.com/history/mopar/electrical2.html

I just sent in my cluster to Redline to have some other things done plus his solid state version-  he sells his soldered verson of the item inside an original housing for $60.  As per url you can make one yourself from cheap components.  My prior post was $20 for a Napa stock type limiter- it worked but decided to go for solid state.  I would also be careful not to drive too much with high voltage from limiter as it can destroy the 3 gauges- not ammeter, which has different design and can take 12v- its normal voltage is 12+v.

[almerkel]

Bob, did you get the gages fixed?

[RECHRGD]

Hi Al, no I haven't fixed them yet.  I didn't realize this thread had come back to life.  Lots of good input here. Thanks guys.  I live so far out in the sticks that I store the car in town during the cruising season, as not to subject the car to numerous trailer rides on my dusty country road.  They don't let you work on vehicles at the storage place, so I'm only a mechanic in the winter when I have her in my own shop.  Haven't had any problems since the original post though.  Bob