disappearing PRND display

[BostonDieselLawyer]

Help!

I have a 2002 Dmax 4WD crew cab long bed 23,000 miles, Delvac 1 every 3,000 miles and Transynd/spin on filter change at 20,000 miles.

My PRND display keeps disappearing and re-appearing. It disappears for 2-3 min then it appears for 30-40 minutes.

NSBU switch has been replaced to tan colored unit but display still disappears. No problems with Allison or engine.

Any suggestions?

[mdrag]

BostonDieselLawyer,

The gear slector display problem you describe suggests a NSBU switch problem. You indicate that the NSBU was replaced with the newer tan switch, and if I understand your post correctly - the problem persists despite the replacemnt. Maybe the replacement NSBU is defective??

I'd suggest unplugging the two connectors on the NSBU and check the terminals to make sure that they were not damaged or bent during replacement. Make sure that the connectors are seated properly. If the problem persists, have the truck scanned for codes.

I don't recall hearing of other reasons for gear selector display problems, but I'd bet a TCM problem would be on the list. Since your truck is a 2002 with 23K miles, the Allison should be covered under the 3 yr/36K mile warranty.

If you have access to the Featured Articles, More Power has an informative article on THE NSBU SWITCH. (http://www.thedieselpage.com/members/features/nsbu.htm)

Good luck.

[Lone Eagle]

I seem to remember when mine did that early on that the park brake had something to do with it. Getting old. I can't remember for sure. Later! Frank

[Turbo Al]

Mine also does the disappearing trick as well, last time I had it in they reaplaced dimmer switch thingamabob -- no help. I have the old style NSBU that has been replaced once. Other lights go out at the same time as well cruise control, tow/haul, message center and high beam indicator.
Al

[rickdlance]

I had a similar problem while towing. It turned out to be a loose ground on the trailer plug. Don't know if that will help. These computers do weird things. My Mom's new Cadillac's air conditioner quit working and it turned out to be a bad power antennae. Go figure???

[BostonDieselLawyer]

Thanks for all the ideas....The connectors and pins on NSBU swith are ok and replaced NSBU switch again .... The transmission shifts perfectly .... but the PRND display still goes out now and again for 30 seconds - 5 minutes then comes back on...also saw no loose wires under dash ... I am reluctant to have local stealer mess with it. Thanks again ...as usual more information in this forum than anywhere else.