I've been trying to track down my dash light issue for a year or so, have read tons of posts and tried a few fixes with no luck. Lately I've isolated an AC gremlin and am sure that it's electrical so maybe they are related. Here's what I've done so far on the dash lights:

1. Grounds - I don't find any sort of ground bundle behind the instrument panel, just the bundle going to the main connector and then the individual lights/sensor signals. I did however: tried grounding to various parts of the rear of the panel; disassembled, cleaned and tested ground across the contacts between the 3 sections; and jumped from the battery - to the chassis and engine. No change on the light behavior from any of these actions.

2. Tried a replacement instrument panel. I bought a gasser from ebay and thought I would move over the necessary gauges and faceplate if it worked, but it shows the exact same pattern of dash lights as mine. I am attaching two pictures to show what I am getting. NOTE: I know this is a gasser (as it says on the fuel gauge) and the tach is pegged because it won't work with the diesel, but the light patterns are the same as with my original.

Now, at the same time that I was chasing these dash light issues, I was fighting an electrical gremlin that I deal with in my AC system. Basically, anytime the AC shuts off - for any reason - it won't come back on until I turn the car off and restart it. This means that I have to put my thermostat on MAX and choose my fan speed before I start the car - any change and it dies. I'm pretty close to getting it going again just with a restart.

Any thoughts? Do you think these issues could be related? From my review of posts and searches, it seems that the OVP and the ignition wiring could be suspect. Does the duel issue help isolate the probable cause?

Thanks for any help.

Attached Thumbnails

   

What dash lights are giving you the problems, idiot lights, night lights?

Not sure whether you can open the pictures from my OP, but the battery light is probably 3/4 powered and the others seem to fade at lower brightnesses. The gauges also jump around, especially the fuel gauge (it will just peg to full sometimes). The tach and clock are solid, no issues.

Thanks.

Could even be the ground strap between the chassis and engine is not really great. I would remove it and clean the contact areas. Put a little grease on them and bolt them back up. Also do the same with the ground strap from the negative terminal to the chassis. May be just enough resistance in the connections to affect some things but not others.

Actually on older cars this is just good preventative maintenance anyways. Also I might suspect the actual wiring harness in the engine compartment. I think your model may be one that has issues with them. Not sure though.

Thanks for your input Barry. I did try a jumper cable in parallel to the ground straps just to see if there were any changes in behavior - nothing. Is that a good enough test? I will clean and lube the ground straps when I can, but for now I am limited to very light work so I have to focus on just the electricals for now.

I was finally able to do some heavy lifting - replaced the LCA bushings and ball joints on the front end. While I was under there I pulled the ground strap and cleaned the contacts - they are shiny enough to shave by. No luck, I still have the same idiot lights on/half one (see pics in original post) and still lose my A/C every once in a while. Turning off the car and restarting it does get it going again.

If A/C works again when you restart the car then it is likely the Kilma relay. The Kilma relay detects the compressor is not spinning and kills the A/C. Either the Kilma electronic is faulty or the compressor shaft reader is dirty. I would try to re-seat the Kilma first to see whether the problem goes away. Then replace the Kilma. It is located behind the battery.

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No luck. I am going to wire in an ice cube relay next week and try that. Any good suggestions for a relay (brand/#) that I can order?

Any other suggestions for the dash idiot light issues?

Two ideas come to mind: check the W1 grounding point (behind the instrument cluster), and make sure your instrument cluster plug is alligned properly (provided the center allignment nub is broken). Good luck

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The only ground that I can find comes through the main (large round) connector plug on the back of the cluster.

The nub seems to be fine - the instrument cluster plug only goes on in one orientation.

I did find enough information online to pinpoint the location of the W1 grounding point. I will be able to look at it next week and reply back to this thread with my results.

Thanks!

Your AC issue as determined by others above is classic Klima behavior.

Two explanations:
- It is doing its job because your compressor is dragging. This is done to make sure that a seized compressor won't shred your belt and you lose all engine auxiliaries.

- There is a problem with the system.
There is a tach sensor on the back of the compressor. The Klima compares this signal to the engine RPM signal as detected by the pickup at the rear of the engine left side. It senses the ring gear teeth (144/rev). There is a math function that is probably specific to this engine, that takes into account the specific differential between engine pulses and compressor pulses per rev. You will probably need the exact Klima relay to make it satisfied. One from a gasser will not work, they have 3 pulses/rev on the engne side because it comes from the spark system.

You can jump out the contacts on the Klima base to get the compressor to run for troubleshooting purposes only.

Best if you have access to an oscilloscope to test this out. You will want to scope the engine signal and the compressor signal and make sure you have a strong signal on both.

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I was able to get a few items looked at last week. Here is my current status:

1. Instrument Cluster - I did locate the W1 ground and cleaned all connections. Contintuity between the ground pin on the round instrument plug and the W1 ground connector seemed iffy so I added another ground from a tab I put under one of the connection screws. No change in behavior - idiot lights still partially on, fuel gauge works sometimes and pegs to full sometimes... Clock is steady and keeps good time (as it always has). I am wondering if the large, round instrument connector is not making good connections within the plug. I may have to find a way to bypass it. Thoughts?

2. I put an ice cube relay in place of the Kilma relay and the A/C works solidly. I need to get access to an oscilloscope to see whether its a speed sensor issue or whether its a problem in the Kilma relay.

So now it's getting worse - and more than just irritating, it's affecting safety. My turn signals are now working some of the time and not others. Any chance that all of these electrical gremlin issues, other than the A/C, are being caused by the OVP relay? I really need to sort this out or quit driving this diesel, and I love doing that.

... I really need to figure out the electrical issue. I can live without A/C and even radio (I've been running a SiriusXM app on my phone connected to a bluetooth speaker). The idiot lights on the dash aren't a big deal. I would like to fix all of this, but when things like turn signals start to go... Any thoughts?

TIA

Tim