No Speedo or Tach
 

Driving into work today in very wet conditions, the speedo and tach jumped around and eventually just stopped working. The WTS and WIF lights no longer come on, and the rest of the gauges seem to work fine. I assume that there is an issue with the PCM getting wet and shorting something. I'm wondering if this is a common problem and what the fix might be.

Once the truck dries out, it might just start working again, but I'd rather not have this problem recur. If it is the PCM, it might be dead at this point and need to be replaced. Following that, I assume there's some waterproofing that will have to take place. Anyone have experience with this?

You need to fill in you truck signature , to get good answers .
Crank sensor possibly .

Good point. It's a '96 12valve.

The issue cleared up after the truck dried off. I still wonder if waterproofing will be necessary.

I like to put dielectric grease in any connection .

Well halbritt,

I hope you can find out whats wrong with your truck and tell me...Mine is doing the same thing, but its had time to dry out and hasn't changed. From what I can tell is its not the connections with the PCM, although there is always that possibility, but after pulling them and popping them back on numerous times nothing seems to help, and I can't imagine a connection just failing while I'm driving down the road.

-Matt

I would also check the Crank sensor and the plug for it, my truck was freaking out no tech, speedo, wts, no charge, no od and no converter lock up, and it end up being the plug on the cps.

Thanks for the suggestion. I have a feeling that a wet or loose plug on the CPS might be the problem. I'll check it out.

What is WTS and OD ???

My truck did the same thing awhile back, it was a bad connection on the back of the guage cluster, pulled it out and cleaned it up, plugged it back in and everything's worked fine since.

Katmandu, WTS= wait to start and OD= overdrive

the same thing was happening to mine and it wasn't the guages being dirty- i wish! same symptoms isyour cruise working? took it to the dealer cause my mechanic was scratching his head and because it's my work horse i figuerd no f***ing around. they had 4 guys tracing wires, manuels all over the place. they had it for the better part of 2 wks. they did rent me a truck though but i couldn't pull my 14' enclosed workshop with a rental-so not much help. anyways, it was the crank sensor AND the pcu. they told me that one took out the other. they were asking me to pay allmost 4000.00 for the repair so i paid for 1700.00 worth of parts and just the actual time spent wrenching. mabey i'll start tellin my customers it's 5x more and then when they barter me down i'll still make a killing. just a few minor problems since the new parts... the cruise keeps speeding up and for some reason, my windshield washer pump is not squirting as good as before! mabey they tampered. looking for some re-work!! good luck tracing wires. wish i had better news.

Check out this thread I have going about this same issue....

https://www.dieseltruckresource.com/...d.php?t=186943

I called and explained this situation to my local Dodge Dealer's Service Manager. He told me I had a bad instrument cluster. [dummy]

I'm waiting for the outside temperature to go up (above 20 degrees) so I can finish working on my truck.

So far I have around $300 in Parts/Repair tied up on it.

$150 for a new (used PCM)
$100 for a new CPS
and $45 for a WRONG alternator diagnosis. [verymad]

It's been off the road for (4) weeks now. Mainly lack of time to deal with it and now the LOW outside temperatures. [verymad]

Did you lose your instrument cluster completely like mine did ???

Check out that other thread. It's more complete and up to date.

https://www.dieseltruckresource.com/...d.php?t=186943

I'd like to know how this type of problem originates.

How does a bad CPS take out a PCM (or vice versa) ????

What is the itemized breakdown on that repair ??

How much was the PCM and CPS ??

How much labor $$ did they charge you and how many hours did they use ?

Kat, save your old PCM, it may be fine.

I just read on another thread that the PCM is supposed to be protected on 96 and up models to prevent the CPS from killing the PCM.

Worth checking out to have a good spare.