Instrument cluster voltage regulator

[lessersivad]

WARNING!!! LONG-ish POST AHEAD!!!

NOTE... I have NOT attempted any testing or 'poking at it with a stick' for the following query..... (I was going to do a 'voltage drop' test on the vehicle Buuuut, my DVOM FINALLY quit functioning all together....

The past couple of weeks I've noticed my fuel gauge and temperature gauge have both been reading (intermittently) higher than normal.
The fuel gauge is the one which got my attention at first. With a reading of 'past full' when (in my best estimation) should have been closer to 3/4 of a tank).
I know I've had past GM products do this and it was simply a bad ground at the tank. So I thought the possible same for the Festiva.

I then noticed the temperature gauge was also reading higher than normal. Which in my mind pretty much ruled out a problem with ONLY the fuel gauge/sender/wire.

Whilst looking thru my factory service manual and reading the 'symptoms, possible causes' it makes mention of an "INSTRUMENT VOLTAGE REGULATOR" and the 'action to take' is to replace the instrument cluster.

I know DECADES ago I fixed a gentleman's 'dent side' F150 by replacing the instrument voltage regulator because of gauges not reading correctly.


So the QUESTION IS (after writing a small novel).... Is the cluster regulator replaceable/available....or do I need to source another cluster to fix the issue???

The issue is ONLY intermittent (as of the past couple of weeks) so there's no 'after I hit a bump/when it's raining/if I'm driving with the lights on/ if there's a full moon/ during an eclipse/etc.

Hopefully you didn't fall asleep during the reading of this and I look forward to any responses to help resolve this issue.

Thanks.

[1990new]

This post is pretty short compared to many of mine.
All my factory service manuals say the same thing yours does .. replace the instrument cluster.
However, there are only three circuit components on the instrument cluster board.
.68uf capacitor (capacitors server as voltage regulators among other things)
100 ohms resistor (I know this is necessary for the alternator to perform correctly)
1N4007 Diode
(The 1N4007 is a silicon power Rectifier Diode for low power and switching applications. 1200V Non-repetitive Peak Reverse Voltage. 700V RMS Reverse Voltage. +350°C Maximum Lead Temperature.)

These components are all very cheap so if you replaced them all with new ones, you would probably have solved your instrument voltage regulator problem.
The one in the picture is from a non tach cluster but I believer the tach cluster has the same three circuit components.

Instrument cluster circuit .jpg

[lessersivad]

Thanks for the information.

Today it never acted up. I did purchase a new DVOM today and so MAYBE if it acts up (or I can at least catch it acting up) I can possibly see IF there's a voltage drop on the ground side.

The car continues to run good.... it's simply annoying me about the gauges reading above what they normally have (and in the case of the gas gauge, I KNOW that's reading above for sure).....not unless it actually IS making gas (as I often joke about).

EDIT... Mine is the non-tach variety so this should be correct.

[1990new]

Thanks for the information.

Today it never acted up. I did purchase a new DVOM today and so MAYBE if it acts up (or I can at least catch it acting up) I can possibly see IF there's a voltage drop on the ground side.

The car continues to run good.... it's simply annoying me about the gauges reading above what they normally have (and in the case of the gas gauge, I KNOW that's reading above for sure).....not unless it actually IS making gas (as I often joke about).

EDIT... Mine is the non-tach variety so this should be correct.

Varying Ohms resistance varied by the sending units is what the gauges use to vary the fuel and temperature gauges. The little bimetal piece attached to the gauges expand and contract based on the heat generated by the amount of current received the sending units.
Over time all the gas gauges in the Festivas eventually fail because the tiny wires wrapped around the insulator in the tank sensor wear through. There are threads here in the forum that describe the problem very well. I have tried to get tiny wire and rewire one but never really got it to work well. After keeping a gas fillup log in my Festivas I'm now in the habit of keeping one in all my cars and record all fillups with date, mileage, gallons, price per gallon, total cost and where I filled up.

The temperature sensors eventually start acting up too. I bought one to put in my radiator hose for Nelly and it works great..nice blue led lite digital reading shows the exact temperature.