Does anyone know where the Instrument Cluster voltage regulator is located on out trucks,

All of my gauges are displaying inaccurate readings.
I do not remember seeing one on the back of the cluster.
Thanks Jim

 

Looking through the factory service manual there isn't one. The panel is supplied by 12 volts and a ground. The only other voltage source is for the lamps. If all you gauges are off, check the supply and ground. Any resistance in either will throw the gauges off.

 

Jim: The Instrument cluster voltage regulator is located on the circuit board on the cluster itself. According to the FSM it's a 5V regulator with 3 terminals and has a metal case about 3/8 inch by 1-1/4 inches IIRC. I speculate it could be replaced with a 7805 type three terminal regulator. It supplies the fuel and oil pressure gauges. I think it's a pulse type or SMPS type since I couldn't measure anything coming out of mine but it works.

Edwin

 

Wow,
I do not see it anywhere unless it is under the plastic cover over the speedometer but there does not look like there is any electrical connections to the unit.

Seems odd they would use unregulated voltage for the insturments.

https://www.dieseltruckresource.com/...l-leds-209884/



Let me know if you cannot see the pictures,
I hope they work.
Jim

 

Jim:

Apparently you'rs is different than the 89. I was talking about mine.

Lemme look in my other FSM diagrams and see what I can figure out.

Edwin

 

Jim:

I have a 92 FSM for a RamCharger that doesn't show a voltage regulator. The gauges run directly off 12 V. I can email you the FSM if your email will handle an 83 MB file. PM me if you want to try that.

Edwin

 

That 5V regulator was only for the old analog gauges pre 90 I believe, or what ever year they switched to a VSS speedo.

 

That would make sense, each gauge would be internally regulated, the 12 volt buss could be anywhere from 10 to 14 volts,

What circuit feeds the instrument panel, I will make sure that circuit is clean, maybe I had accidentally tied another load to that circuit or maybe it's just a bad connection.

Thanks

Edwin,
Do you have access to an FTP server

 

The 90 gauges are different than the 89 so that makes sense.

 

Jim:

Check for a PM from me.

Edwin

 

Looking at that picture, do you have the same gauges as the '91.5 forward, but with a mechanically driven speedometer?

That is more or less what it looks like to me, but then '90 would be a really "odd-ball" year for the instrument cluster . . . I thought most of the transitional electrical stuff happened in 91.5.

Sorry, this probably isn't helpful for you, but I'd like to get a handle on these year to year variations.

 

I have the VDO electronic speedometer head,
I'll see if I can check some voltages at the cluster.

 

The odd ball stuff did happen in 91.5 for the CTD trucks only as that is when they got an overdrive trans and cruise control. The previous gas trucks already got that stuff in 89 IIRC when everything went to electronic fuel injection.