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mgambalie · 06-01-2019, 07:35 PM

2000 National, Freightliner Chassis

My instrument panel quit during our last road trip, it started with guages acting up about 1/2 at a time then they would stop and the other 1/2 work for a while. Progressing, whenever we hit a bump in the road they would all go off and reset like when the ignition is first turned on, then finally nothing at all -- no lights, no gauges.

Searching the issue here, there were multiple recommendations to add a ground wire, but I cannot find any place to do that.

There is also a link to service bulletin 54-12 that has troubleshooting steps (including testing for ground and power at specific pins) but the connectors on the Message Center do not match mine -- any chance someone can point me to the correct similar document?

I called Freightliner to see if they could direct me to a similar document but they did not find one, suggested driving to a service center to test the VDC.

I have already tested the fuses and relays

Skip426 · 06-01-2019, 11:53 PM

Have you cleaned the connections at the VDC ?

Yours if the first issue I've heard of that the 54-12 wasn't the document for the wiring on coaches of our era.

Darwin · 06-02-2019, 04:01 AM

2007 Freightliner I replaced the Light Bar Controller a few months ago. About $500 from Freightliner. I tried getting it repaired at an instrument shop. Part of the LBCU is sealed and not repairable.

mebden · 06-02-2019, 06:24 AM

Hey Darwin sounds to me as the instrument cluster needs repair like mine did from a previous post I replied to not sure what instrument shop you tried but I had to send mine out for repair to a company that works on the older instrument clusters but very quick turn around. The company I used was R.T. Grim out of PA. Look them up give them a call maybe able to help you out

asuperheat · 06-02-2019, 12:10 PM

I also had a bad LBCU. My entire dash would drop in and out. Eventually quit all together and did not come back on. A new LBCU fixed it.

mgambalie · 06-04-2019, 08:01 PM

Quote:

Originally Posted by Skip426

Have you cleaned the connections at the VDC ?

Yes, I removed both of them, sprayed each side with contact cleaner, then connected/disconnected several times.

Quote:

Originally Posted by Skip426

Yours if the first issue I've heard of that the 54-12 wasn't the document for the wiring on coaches of our era.

I stand corrected; I rechecked both connectors and they DO match. I will start the troubleshooting list tomorrow in daylight.

The first two "Remedies" require checking harness continuity -- Did I miss a page, do we get the endpoints from another source, or does that mean unwrapping the spaghetti and following it down?

Skip426 · 06-04-2019, 08:42 PM

Quote:

Originally Posted by mgambalie

The first two "Remedies" require checking harness continuity -- Did I miss a page, do we get the endpoints from another source, or does that mean unwrapping the spaghetti and following it down?

Are you in the first two troubleshooting items on page 6 ?

mgambalie · 06-04-2019, 08:52 PM

The first two on page 6 and page 7. I was trying to jump ahead to the MC pins tonight, I will wait for daylight to check the VDC pins.

Skip426 · 06-04-2019, 08:55 PM

I'll see if tracing through my wiring schematic , will provide any insight into the power supply for those wires.

mgambalie · 06-05-2019, 04:21 PM

Working through the steps today, I may have figured it out, please correct me if not.

The steps have us check pins at the VDC and the MC for the same values -- do I assume correctly that those are the two endpoints of "the harness" to check for continuity?

I got to step-3 (first on page 7) and have 22 ohm to ground on MC pin-8, VDC pin-G is dancing all over the place, it doesn't settle long enough to take a reading. If I understand this to be "no ground" then I assume the harness continuity check will be from the MC-8 to VDC-G... I have round up 20 feet of wire to test between those two points.

Skip426 · 06-05-2019, 04:39 PM

Quote:

Originally Posted by mgambalie

I have round up 20 feet of wire to test between those two points.

I'll re-read your post and the 54-12 and get back to you .

I've used a 120v extension cord to run from one end of the coach to the other for continuity checks . Ohm check the cord first , but it'll probably be just fine.

mgambalie · 06-05-2019, 04:58 PM

Quote:

Originally Posted by Skip426

I'll re-read your post and the 54-12 and get back to you .

I've used a 120v extension cord to run from one end of the coach to the other for continuity checks . Ohm check the cord first , but it'll probably be just fine.

Thanks,
now why didn't I think of that!

Skip426 · 06-05-2019, 05:01 PM

Quote:

Originally Posted by mgambalie

Thanks,
now why didn't I think of that!

It's not that I'm older , it's just that I've spent more time with my back to the wall .

Thank you " Dr. Hook "

Skip426 · 06-05-2019, 05:16 PM

Ok , I'll have to do some digging here , because to me the procedure isn't clear , are you checking the harness from the dash to the VDC , or checking the connectors at both ends , for continuity to ground .

OK , I've been scrolling back and forth between , the pdf of 54-12 and your post and I think I'm going to have to print out the pdf to save some time .
To be 100% honest , I haven't run these tests so I'll be taking a while to print out the pdf and my schematics to trace the wiring through .
It may be later tonight but I'll be back .