M1008 Instrument Lights and Volt Gauge?

I noticed the other day when I turned my lights on that I wasn't getting any instrument lights. I rarely drive this truck at dark so it's not been a big deal, but I would like to know how to go about trouble shooting this. Same goes with my volt meter. It's never worked and I assume I'll have to order a new one, but I thought I'd see if there's any trouble shooting I can do first.

Start with the simple stuff. Check the 10 amp fuse at the bottom of the fuse box. On my recently acquired M1009, both batteries were charging just fine but I did not have a GEN 2 light nor was the volt meter functioning. All it ended up being in my case was a missing fuse - both are working fine now.

Check your tail lights too. Somewhere in the back of my head I seem to think the tail lights and dash lights are on the same fuse. Did you try messing with the light switch twist? Those switches were not the best quality when new.

The volt meter is on a 24V circuit and there is one 24V fused circuit in the fuse box. The instrument cluster is 12V, with the exception of the Gen 2 exciter circuit.

here are a few tings to check:

It could be just a fuse, agree checking and cleaning them is a good place to start.

Instrument cluster is run though headlight switch, another thing to check. If under dash light works when dimmer is fully rotated, then switch is probably not the problem.

There is a 6 prong ground clip above the parking brake pedal, usually there is only one wire there, and it is ground to the 24V circuit in instrument cluster and volt meter.

The volt meters often do go bad on their own though, so it could be two separate problems.

dependable said:

The volt meter is on a 24V circuit and there is one 24V fused circuit in the fuse box. The instrument cluster is 12V, with the exception of the Gen 2 exciter circuit.

here are a few tings to check:

It could be just a fuse, agree checking and cleaning them is a good place to start.

Instrument cluster is run though headlight switch, another thing to check. If under dash light works when dimmer is fully rotated, then switch is probably not the problem.

There is a 6 prong ground clip above the parking brake pedal, usually there is only one wire there, and it is ground to the 24V circuit in instrument cluster and volt meter.

The volt meters often do go bad on their own though, so it could be two separate problems.

Click to expand...

I pulled the fuse and replaced it just to be sure, but that didn't change anything. There's no under-dash light that comes on either when my dimmer is fully rotated.

I checked the grounds for the 24V meter and the looked good.

The under dash light is located under dash between the ash tray and glove box, if you want to check the bulb.

Are you getting 24V to the positive feed on meter? If so, the meter is probably bad. The dash lights could easily be a separate issue.

I checked the under dash light and its not blown. So now I have to figure out if the light bulb is good, and the fuses are good, why isn't anything working?

If under dash light works, it confirms there is current coming out of service light dimmer switch. When you say bulb is "not blown", I'm assuming you tested it and it is OK. If this is the case and it is not coming on, then it could be a problem with dimmer part of headlight switch. You will need that volt meter or test light to proceed much further.

If under dash light works, but you have no dash lights, it is possible that all the bulbs are burned out or have bad contacts to the plastic sheet the dash circuit is on, also possible the contacts need to be cleaned where wires plug in to cluster assembly. 35 years of dust, corrosion and possibly a little mouse urine can easily break these small contacts.

On all the CUCVs (and other trucks of this vintage) I get, I take the dash pad off and clean up accumulated matter and clean contacts, lube heater cables, etc. It takes a little time, but worth it in my opinion.

Check fuse #13 and #16

CUCV Fuse Box

I've checked all the fuses, and they're all good. I checked the lightbulb for the underdash light and the filament is fine, so it must not be getting power from the dimmer controller. I still get my headlights to turn on though. I'll make a point to take the switch out and clean all the contacts and see if it helps. If not, I'll order a new switch.

You would do yourself a favor to have some basic test gear, even a test lite. Also might not be good to assume dash light good by visual inspection of element. Can't help further with info provided, good luck.

I'm to the point where I've changed the headlight switch, and my under-dash light came back on, but I still have no instrument panel lights.

Probably time to take out the cluster, clean some contacts and check some bulbs. It is not difficult, but can take some time if your have not done before. I usually take the dash pad off, makes it easier to get the speedo cable off back of cluster, and get a look at heat control too. If taking the dash pad off, try to find and take out all fasteners before you start to remove, makes it easier.

I took the cluster out, cleaned the circuits with contact cleaner, and replaced all the bulbs. I decided to replace them all seeing as I had the thing out. Put it all back together, and it works like a champ.

Now I just need to order a new 24v voltmeter and I should be set.

You has PMed me saying you were looking for a repair solution for the shift indicator that was broken. Here is an idea to do a painless low cost effective repair. Good Luck. I used a T nut as a glide and greased the cable to keep it moving freely.