ponynx

i purchased a 97 f150 4x4 and it has 92000 miles on it its been driving fine for a few days until today when i was towing a snowmobile trailer and the o/d light started blinking . turn the truck off and it stopped.........it did this a few times so when i got home i disconnected the trailer and headed to work to scan the computer ...........light would not come back on with the trailer disconnected no matter what. scanned the computer and it came up with p0503 vss intermittent signal .....ok so it may need a speed sensor no big deal, but why does it throw the code only when it has the trailer connected? other than the light the truck shifts fine with no issues ..it has a 4r70w transmission as well. trailer connected code, no trailer no code . could the vibrations and jolting of the trailer cause the speed sensor to have an intermittent issue?

cole_ford

Usually when the O/D light blinks, it means something could be going wrong with the tranny. You need to have it checked out by a tranny shop soon. They have the proper scanner.

ponynx

thank you for the reply, ill also note that im using my snap-on solus-pro scan tool ........all shift pressures and all other transmission fuctions are normal . i also ran 2 other tests on the pcm , koer and koeo and both passed with no additional codes or pending codes.like i staed the light will ONLY come on if the trailer is connected .i also strapped the truck on my chassis dyno and ran it hard through all upshifts and down shifts and under a hard load in o/d with no issues but with the trailer on the truck the damn light will come on , lol .

torkum

Intermittent signal could also indicate a wiring problem.

ponynx

i guess tomorrow ill drive the truck with the trailer and see if i can get it to flash again while i have the scanner connected, ill data log and see if i can see it through the pid's . actually ill have to wait till tues we are supposed to get another 12-14 inches of snow tomorrow .

farmerboy3

hah every time it came on in my dads 1998 f150 he always pulled over turned the truck off and started it and it would be gone for 6 month

ebxgsxr

same thing here. even when it is blinking appears to be driving fine with no issues. like right now everything appears to be ok & no light. im just expecting later ill need to have it either rebuilt or throw another one in.

ponynx

in my case i dont think it an internal transmission issue at all ...........with the vss code being the only . if the transmission was having any issue id be seeing a code that was directly related to the transmission itself. plus it will only do it when i have the trailer connected.

Good old Bill

Seems like you are doing all the tests, and have all the gizmos to do it with. Sounds like you are convinced its the trailers fault? Why didn't the dyno simulate the load of the trailer? I admit that I'm no technician, just an old mechanic, perhaps while on the dyno, you pressed it harder than the actual driving with the trailer. Next time while driving with the trailer, note the RPM and speed so you can duplicate. A wild **** thought, the electrical connection to the trailer can't have anything to do with it, can it?

ponynx

update: talked with my friend over at the ford dealer , he had no clue, swung it by the shop that rebuilds automatics for me and he stated the transmission is fine , but to try a new vss sensor just to see ........so i dunno,lol . while it was on the dyno its hard to recreate the exact situation while towing ............what ill try some other day is to have it on the dyno and reach under the truck and tap the sensor and see if it makes it lose signal , rather than that i am giving up for now,lol.i appreciate the input from everyone though !