PSOM, clockspring, or ???
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Elder User
Joined: Apr 2008
Posts: 727
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From: north shore, minnesota
PSOM, clockspring, or ???
bought this truck as is 3 months ago and let it sit in my yard and just getting to it now. 1994 F-150 4.9L E4OD 4x4.
Speedo, odometer, cruise, & horn don't work and the transmission shifts hard and at wrong points. ABS light is on steady.
ALL fuses in and out are good. All brake lights work with new bulb in the high center.
New speed sensor in the rear diff with no change.
I've searched and read this topic through and through but..... am I just guessing at this point between the PSOM or the clock spring? or is there a speed sensor in the trans, one with a gear on it, that could be the culprit?
The Ford engineer who wired this thing is a real work of art I tell ya, wow.
Speedo, odometer, cruise, & horn don't work and the transmission shifts hard and at wrong points. ABS light is on steady.
ALL fuses in and out are good. All brake lights work with new bulb in the high center.
New speed sensor in the rear diff with no change.
I've searched and read this topic through and through but..... am I just guessing at this point between the PSOM or the clock spring? or is there a speed sensor in the trans, one with a gear on it, that could be the culprit?
The Ford engineer who wired this thing is a real work of art I tell ya, wow.
Fleet Owner
Joined: Aug 2005
Posts: 23,668
Likes: 301
From: Easton,Ks
That year did not have any speed sensors on the transmission.
The horn would not have anything to do with the VSS speed input to the PCM.
Does the Odometer light up with the mileage when you turn on the key?
If so you can try unplugging the ABS module and see what happens.
If you still have the VSS problem plug the ABS back in and unplug the PSOM. Then check the VSS signal from the rear end with the Hz display on your DVM.
You should have about 667Hz with about 30MPH rotation of the rear wheels.
OR
You should have about 3.5 AC Volts with about 30MPH rotation of the rear wheels.
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The horn would not have anything to do with the VSS speed input to the PCM.
Does the Odometer light up with the mileage when you turn on the key?
If so you can try unplugging the ABS module and see what happens.
If you still have the VSS problem plug the ABS back in and unplug the PSOM. Then check the VSS signal from the rear end with the Hz display on your DVM.
You should have about 667Hz with about 30MPH rotation of the rear wheels.
OR
You should have about 3.5 AC Volts with about 30MPH rotation of the rear wheels.
/
Freshman User
Joined: Apr 2018
Posts: 26
Likes: 0
From: North Carolina
Is your seat belt light on? My clockspring went out in my 1994 302 5 speed and the horn and cruise would not work, and the seat belt light was continually on. I say your problem is most definitely the clockspring, and maybe a combination of clockspring and something else.
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Elder User
Joined: Apr 2008
Posts: 727
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From: north shore, minnesota
Fricken clockspring is like $300 and a PSOM used is $70 so maybe convince the wife to buy a parts truck for $500 and be golden?
I have a running driving '89 "parts truck" for my plow truck / trail rig '89 F-150.
Has me thinking, **** all this electronic crap and just put the 5 speed drivetrain in from my 89 parts truck?
I have a running driving '89 "parts truck" for my plow truck / trail rig '89 F-150.
Has me thinking, **** all this electronic crap and just put the 5 speed drivetrain in from my 89 parts truck?
Cross-Country
Joined: Sep 2014
Posts: 80
Likes: 7
I just went through this and have changed the psom and the clock spring in my truck. The pick and pull will have them. Thats why i like this generation of ford is because there's usually a million donor vehicles in the junkyard. Pull the circuit chip off the back of the speedo and plug it into your speedo and see if that fixes your problem. The part was 3 bucks. Or you could get a clock spring and try that first. It might be easier. The horn points to clock spring in my opinion.
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