Hey guys, 1996 f250 460 4eod 2wd. Just as the title states, went to use my truck, and noticed the hard shift first. It was accompanied by blank odometer, speedometer not working, and the flashing overdrive light on the shifter stalk. This has happened randomly twice before in the past. Before, it was while I was already on the road, and was able to cycle the key, and everything went back to normal. This time it happened right from the beginning, cycling key had no effect. I thought great, now I have a hard fault to diagnose….
Did some googling last night, leading me to my fuses. Checked fuses, all good there. More searching led me to my speedometer psom, ok I’ll check that in the morning.
Get in truck today, and of course everything is working right….<ugh>
I went ahead and pulled the cluster, all the connectors look good, pins don’t look corroded, wires look fine. I did not separate the speedo from the cluster.
A lot of the threads I’ve read on here, are dead ends, either it turned out to be fuses, or no further response after being told to check the wiring at the psom.
Anyone have any ideas what this could be? Is my psom starting to go out?
Any help is much appreciated, but it’s always tricky finding an intermittent fault…
Thanks!

 

Went ahead and peeked at the psom before I put everything back together. The black disc has a spot near the top left, close to where the wire comes out, that looks like it is oozing something, and left a smear/streak when I wiped it with my finger. Also not sure if that white squiggly line is supposed to be there either? I saw a YouTube video showing these components, and part number info, gonna have to watch them again and maybe replace this part?

 

A dead speedo and a blank odo is caused by one of two things, fuse 8 or 18 being blown or a bad PSOM. Most folks will ship the PSOM to have it repaired.

 

If you need a PSOM for testing or for quick repair, any 92 & up works with 95 & up resisting needle shake the best.

You'll loose the mileage, unless a chip is de-soldered & transferred, but it'll get you operative.

 

I take it you can't get a new one anymore
I think I have one in my toolbox that was replaced under warranty, it did not fix the problem, so I ended up keeping the part when Ford did not call for it
Aren't they dime a dozen at the junkyard?

 

Right now it works. Maybe pulling the fuses broke the corrosion? Maybe I’ll keep an eye out for a psom, it’s not too hard to get to… I’ve soldered boards before, the black disc is the only suspect piece I see, shipping is about 8 time the cost of the part…

 

what did you end up doing, I suspect I have a dead PSOM i have cluster out and will check it for obvious damage, got good ground(2) and power in 1,3 pins