'97 F350 speedo issue

[scotts90ranger]

My speedo doesn't work right now, neither does the odometer, my 30 mile commute was apparently 12 miles this morning . Sometimes it'll work fine until 50mph then go bonkers from there, or just go to zero, then others it won't move at all.

I looked at the transfer case and didn't see a speed sensor, so I'm guessing it's the sensor at the rear diff driving the speedo/odo. I pulled the sensor when I got home and there were a couple itty bitty pieces of metal stuck to the sensor, wiped them off and took a test drive and that wasn't it. Would this mean a bad sensor or something else?

Thanks!

 

[Enemy]

Sounds like the PSOM module on the gauge cluster is going out. My 97 F250 and a 93 F150 did the same thing. Replacing the speed sensor in the diff may remedy a bouncy needle but only for a short while from my experience.. And the places that will repair the clusters want an arm and a leg to do it from what I have found. Just picked up a low miles cluster from a local salvage yard for $75 for the F250 that has been working beautifully. I have quite the pile of clusters laying on a shelf from over the years that either bounce all over the place causing eratic shifting or just slam to 0 while going down the road LOL! Definitely not one of Fords brighter ideas to convert the speed sensors signal for the trans through this module!

 

[scotts90ranger]

dang, not what I wanted to hear... I'll look for a cluster then, add it to my junkyard list. Is it just the module, or does it replace the whole speedo section of the cluster? My odo has a little over 333k on it...

 

[scotts90ranger]

Did more looking, and it doesn't look too bad, I'll try to get the PSOM out tomorrow and see if it's just a bad minor component or bad connection... that would be nice

 

[Enemy]

333K!!!! Thats awesome! Im a little surprised it went that long! Sure would be nice to figure out what goes bad in these things and if it is repairable in the garage.. Mine went out on the powerstroke at 220k, and the worst part about it is loosing the actual mileage reading we spend so much money to accumulate LOL!
Pulled one apart tonight, PSOM is integrated with the gauge needle..

 

[scotts90ranger]

I just got it a year ago, so all those miles aren't mine and who knows what the thing's been through... apparently it had the engine replaced about 200k ago. For what it is it does good though, gets 16mpg driving wherever, and will tow whatever you put behind it, it'll be slow but it'll get there , somewhere around 12-13mpg with an extra 8k pounds isn't too bad.

Yep, got to the same point on mine tonight, I think someone's been in there before since things were a little loose. Apparently sometimes there's resistors and such that go bad which I don't see on mine or yours, I'm going to try to contact a couple places in the next few days to see if they can help out. I also learned last night that you can program the PSOM for different tire sizes pretty easily yourself which is pretty nifty.

 

[Hagan]

Apparently you can only reprogram the PSOM 5 times. My odo has 235k miles. I had to replace my tach with one from the junk yard.

 

[scotts90ranger]

Ok, my problem is solved, it was apparently a connection issue at the speedo, I put it back in and it's working just fine.