Strange PSOM problem
Thread Starter
Junior Member
Joined: Mar 2019
Posts: 3
Likes: 0
Strange PSOM problem
Hey so I have a 1993 F150 xlt with a 4.9l I6 300. I have changed the VSS in the rear diff, I swapped the cluster out(still have the old one) and checked the fuse. Now mysteriously I pulled the truck out of storage drove it for a week moved into pittsburgh and drove her back home. Went back 3 weeks later started the truck take it down the road and that dang speedo needle went bonkers. Its the E4OD tranny and the last time i had an issue it threw an engine code and it happened to be the manifold absolute pressure sensor. This time I dont think its that seeing as while I'm driving if the needle goes nuts and the truck begins to bog down spit and sputter like an 80 yr old man with emphasizema, I pull the cluster fuse and it smoothens out but obviously shifts like im getting rear ended. i need some help here.
Member
Joined: Jan 2018
Posts: 11,256
Likes: 1,770
From: Memphis, TN, Earth, Milky Way
The PSOM does not impact the EEC's logic for managing the engine; only the transmission.
(phone app link)
My first guess would be that the EEC capacitors are leaking. Click this & read the caption:
(phone app link)
It will be easier for us to help you if ALL the truck's details are in your signature, as this caption explains:
(phone app link)
(phone app link)
My first guess would be that the EEC capacitors are leaking. Click this & read the caption:
(phone app link)
It will be easier for us to help you if ALL the truck's details are in your signature, as this caption explains:
(phone app link)
Thread Starter
Junior Member
Joined: Mar 2019
Posts: 3
Likes: 0
I’m new to this forum thing so I do apologize I’ll fix that but it’s a 1993 F-150 XLT E4OD 4.9l I6 300. I am just lost here. It does not have a VSS in the transmission. It is lifted 6 inches on 35s I bought it like that now I looked at a wiring diag to see all the grounds where the PSOM might be Grounded and it looks like it runs through the cig lighter... it was disconnected when I bought the truck I connected it and 3 weeks after the fact I had this issue I just unplugged it wanting to see if anything changes. What other information on the truck do you need?
Thread Starter
Junior Member
Joined: Mar 2019
Posts: 3
Likes: 0
Somewhat fixed the issue!
I had a truspeed Superlift Speedo calibrator that was in the truck when I bought it. The connections were loose and it ended up shorting out the truck. Couldn’t start it so I looked around the fuses blew a maxi fuse.. figures. Replaced the fuse and hard wired the vss back to the psom and got rid of that dumb super lift module. Everything is driving great, however my speedo needle bounces around 45-55 truck doesn’t shift funny though. I’m happy with that but any one have this issue?
Mr. Fixit
Joined: Mar 2019
Posts: 113
Likes: 52
From: The Great Pacific Northwet
I had a truspeed Superlift Speedo calibrator that was in the truck when I bought it. The connections were loose and it ended up shorting out the truck. Couldn’t start it so I looked around the fuses blew a maxi fuse.. figures. Replaced the fuse and hard wired the vss back to the psom and got rid of that dumb super lift module. Everything is driving great, however my speedo needle bounces around 45-55 truck doesn’t shift funny though. I’m happy with that but any one have this issue?
Check the tone ring to speed sensor gap.
Check the tone ring runout.