Hi Guys, Merry Christmas!

My instument panel has now been replaced 3 times. The original Electroluminecent display was intermittent, 1st didn't light at all,
2nd had a speedo problem and now the 3rd seems to not light at all in the cold. My garage was about 20 deg this morning and no light. When it ran for a few minites the other day they came on. In further testing I don't think temperature is an issue or the cluster itself is bad. I called SVT and they said it could be a bad ground somewhere else in the truck, they might only be dim in the cold weather. This shouldn't be this difficult.

Anyone have any ideas??????
Wiring diagram of dash panel and disassembly??
HELP !!

 

The wiring harnesses in the Lightning are almost modular in construction. The entire dash harness is a single unit that interfaces the ECM and the cluster. It does have grounds on it. but they are not where you'd think they are located. Having three clusters with the same problem says to me the problem is in the harness, not the cluster. It may well be a bad ground and if you wanted to unwrap a portion of the harness, find the black ground lead and run a new ground it could fix the problem. BUT: This sounds like a warrantly issue and if you start modifying the harness, they may deny the repair. I do have two more things I can offer that may help. I have a complete, know to work, cluster and a dash wiring harness. Swapping the cluster is easy. The harness is not. It is probably a six hour job after you've done a few. E-mail me if you want to try the pieces.

 

A bad ground would probably not cause it to fail in the cold only, and then come on after it warms up. Do the EL panels in the lightning have a seperate power supply for them? Or are they lit with 12 volts from the battery? I have encountered the same problem you describe on the airplanes work on. They have a seperate power supply for the EL panels. Is the lightning the same way?

 

Thank you for offering your cluster and your help. I think at this point the first cluster was fine and my dealer is going down the wrong road, I'm afraid he maybe over his head. I let it run for a while today and no light. This last cluster worked for about a week. In changing it they probably disturbed the real problem.
Is there a diagram of the cluster wiring available somewhere and I guess I will did in myself. Looks like it is easy to get to.
This is a warranty problem however my truck is more there than home at 120 miles round trip.

 

You could possibly have a ground problem in the cold if you have a loose ground connection, or more specifically, a bad crimp and/or connector that the ground lead runs through. It is not common, but not impossible either. What happens is in the cold metal contracts and in the warmth it expands. With an improper crimp/connector assembly it could contract enough that the gap created between the two bad connections has too much resistance to provide a proper ground of less then 1 ohm. We are not talking much of a gap either.

Another possibility is corrosion between connections, either in the crimp/connector or where the ground lead is bonded to the frame ground (nut or bolt). However, usually with corrosion, it doesn’t fix or repair itself due to temperature. Therefore I would rule that possibility out.

Thus, in the cold you could have a problem maintaining a good ground connection if it is not a proper “tight” crimped connection. As has been mentioned that is defiantly a warranty issue and if you still have a warranty have the dealer deal with it because I can just about guarantee you once you start modifying any of the wiring where the dealer can tell they will void any part of the warranty that deals with electrical.

 

Easy check on the cluster: If you know anyone with a similar year F-150 or Lightning, swapping the cluster is not difficult. When your cluster is plugged into another truck and lights up, you can be pretty sure it is the harness. A lightning cluster illuminates just fine in a standard truck. The boost guage is mechanical, not electrical, so the wiring connector is the same.

The trick to removing the cluster is getting the headlight **** off. Some of them have a release tab that accesses when the **** is turned, others have a tiny slot for a screwdriver in the bottom of the ****. I'm not at my shop this week, so I can't look at a sample to help.

Wiring diagrams seem to have given way to diagnosis manuals with several tests to pinpoint a problem. If there is a real wiring diagram available for the Lightning, I'd love to have one. I do have a genuine shop manual set, which includes the wiring section, but there does not seem to be a complete diagram of anything. That's probably because the current trend is toward replacing rather than repairing.

 

If there is any slack, why not try to wiggle the harness in different areas around the cluster a little. If you can make it come and go by movement, you should be able to isolate it quickly.

Lew

 

I have not taken it apart myself yet because it is under warranty and don't want to void it however lights at night would be nice.
Do anyone know if the panel just has a normal 12 volt feed that is varied by the dimmer or is it a constant 12 volt and a variable signal from the dimmer with some internal electronics to provide the dimming????

Thanks guys for the responses and help.