changed out the pigtail last year and all was good. til this year and its doing it again.

 

Are you talking about the PSOM or the instrument cluster? I wasn't aware the PSOM was a replaceable unit. I thought the entire instrument cluster would need to be replaced. While we're on the subject, where is the PSOM located? I thought it was integrated into the instrument cluster. Can the PSOM be tested in the driveway or does it need to be sent somewhere back East?

I'm interested in what the book says, too. Does the VSS signal go to the PSOM first, then the PCM or the PCM first and then the PSOM?

I'm curious about this question, too. What does the third brake light have to do with the VSS issue?

 

If the speedo continuously acts up, I would take a look at the tone ring on the ring gear in the rear axle. Put the rear axle on jack stands, put the truck in neutral. Pull the VSS and rotate the driveshaft. Inspect the tone ring while you rotate it. If it's got teeth missing, it will cause the speedo jumping, tranny problems etc. And the down side is if the tone ring is chewed up, there is only one thing that will do that.......broken gears.

 

I haven't had a chance to look at the manual. Been working all weekend. I understand that the brake switch circuit runs through the 3rd brake light and then to the pcm.

 

RD, I hope that's not the case for me. I'll be taking a look this weekend.

Thanks for the info Steve. I'm gonna go check my third brake light right now.

The bulb is not functioning. If this fixes my problem, I'll be amazed. Gotta get ready for work, so I'll see if I have a replacement bulb to install.

 

Did you fix the third brake light and you problem went?

Let me know please.

Craig you asked if the PSOM was integrated in the instrument cluster , yes it is ,but its an independent part that can be replaceable. I think there are some companies that can test and fix it but I dont remember which ones, sorry, Ill try to find the info. for you.

 

It is definitely shifting better, but the truck is really sluggish. That may have something to do with the sticking brake caliper. I just rolled 210,000 miles, so it seems like I'm finding new things all the time. Don't you wonder what the engineer was thinking that put this part of the wiring system together?

 

I had very similar happen to me, replaced the vss when it was actually happening and no difference. pulled my instrument cluster out and local dealer sent it to a company to test and fix. Well they said the psom was no good but couldn't fix it because the parts aren't made anymore. Ended up getting a used cluster. hasn't done it since, been 8 months maybe. If there is a place that can fix them I would like to know and may have my original fixed.

 

I bought a used cluster awhile back, but haven't installed it or had it tested because IDK where to take it for testing.

Does anyone have a photo of the PSOM? Maybe a photo of its location in the cluster?

If I can swap it into my current cluster, that would be good, but the PSOM stores the odometer reading doesn't it? If I'm right about that, I might as well install the other cluster, if it tests good (if I can find a place to test it).

 

My original cluster has a sticker and says to call Ford electronics with a phone number

 

That is a great photo, Jim. I'm adding the phone number to my phone right now.

Thanks.

 

Your welcome. Like I said I was told parts aren't available anymore. IDK.

 

The PSOM is integrated in the central part of the cluster (the odo behind the white part), look this pic, maybe helps you. And I found the company that repairs them
Speedometer & Gauge Repair - Home

 

I almost think I called them but maybe not. Maybe I will try it tomorrow

 

Yes it stores the odo reading and according to the law if you put another one it has to match your mileage, and till I know that company can match them. You just can change just the odo and see what happens.