Hello!

I've been going through ol' Esmeralda here since I picked her up last year, replacing and repairing what has been used and abused over the years from previous owners.

I've had an intermittent issue for quite a while regarding OD, speedometer and voltage/battery gauge. Sometimes when I fire up the truck all systems are go and the trans shifts to OD as expected. Other times those 3 items are dead from the get-go and never fire up. Lastly, sometimes these 3 will activate or de-activate periodically while driving; its always all 3 work or do not work simultaneously.

I replaced the VSS with a new unit and it did not resolve the issue although the allen-key type "driver" was starting to round at the edges a touch.

A buddy of mine brought over his voltmeter and we followed some electrical testing instructions from my store-bought repair manual and online; it appears that the fault lies with the PCM. I had previously hunted down, unbolted and cleaned the ground connections and also inspected a bit of the wiring, without seeing visible damage/corrosion. Also checked the fuses in the box under the steering column and the fuse next so the Auto Shut Down relay on the fender.

NAPA can order a reman. PCM for me at around $278 with an $80 core...

My question is, over the long haul have you guys found it more practical to replace the PCM or start eliminating the computer dependencies? I have been reading on this and other forums about wiring in a manual OD switch, using a GPS or etc to replace speedometer function, doing an external voltage regulator, etc. I also came across more info on how to address the other components controlled by the PCM like A/C and grid heater.

The PO already bypassed the FSS with a manual shut-off cable hanging under the dash, and I have a manual switch for the lock-up torque converter he had installed. I haven't had to actually manually flip switches to turn OD on/off before so I can only speculate on whether it'd be a pain in the rear or not. I don't terribly mind locking up the torque converter so far although in regards to OD i could see pro's and con's to both. LOL may make the dash look a bit redundant considering I do have the stock OD on/off button on the dash still.

This is mostly in regards to long term cost and practicalities. I've seen some had the reman. PCM go out on them within a year or so after replacement, which sounds pretty lame and costly! Can any of you bombers weigh in on the pros and cons of this - eliminating/bypassing the PCM as much as possible?

The truck details should mostly be in the sig but can provide more info if needed. I do like the idea of eliminating as many sensors and electronics as possible. It's one of the main reasons I bought -and plan to keep!- this 1st gen cummins as opposed to the newer models; I am not a fan of how overly electronic new vehicles are.

ALSO FWIW in the long-term plans I'd like to swap the auto trans for a manual, for personal reasons. Unless mistaken, I believe this would affect the PCM/no PCM deliberation because of auto/manuals requiring different PCMs and I don't want to buy one twice. From what I've read, isn't it also "easier" to run less sensors/electronics with a manual setup than auto?

Thanks in advance