VSS?
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VSS?
Ok. I have checked here and read a lot of threads but it's time to ask questions.
My 95 F250 with a 460 automatic intermittently would have the od light switch on and off and shift hard. It would always stop after I turned the truck off for awhile, then it would run fine. Well the other day it did it again only the speedo and odo went out. Not reading anything. Well, I went to the dealership and picked up a brand new VSS sensor and replaced it, disconnected the battery and test drove it. Speedo/odo still blank and not reading, OD light is still flashing and shifts are still hard.
I have replaced the VSS
checked fuses...all are fine
pulled the cover off the steering column and inspected wires...all fine
checked the trans fluid level, color and smell...all fine.
What in the world do I need to do next???? Any ideas?
My 95 F250 with a 460 automatic intermittently would have the od light switch on and off and shift hard. It would always stop after I turned the truck off for awhile, then it would run fine. Well the other day it did it again only the speedo and odo went out. Not reading anything. Well, I went to the dealership and picked up a brand new VSS sensor and replaced it, disconnected the battery and test drove it. Speedo/odo still blank and not reading, OD light is still flashing and shifts are still hard.
I have replaced the VSS
checked fuses...all are fine
pulled the cover off the steering column and inspected wires...all fine
checked the trans fluid level, color and smell...all fine.
What in the world do I need to do next???? Any ideas?
Fleet Owner
Joined: Oct 2005
Posts: 20,780
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From: Kentucky
Fuse 8 and 18 supply power to the PSOM. Fuse 8 is Keep Alive power, Hot at all times. Fuse 18 is switched. If the fuses are good then you probably have a bad PSOM.
Pull the instrument cluster, inspect the PSOM on the back of the speedometer for signs of leaking capacitors, broken leads, burned components.
A photo from Steve83:
The PSOM is the board on the lower left of the photo.
More info: What's a PSOM?
I HIGHLY suggest you put the original VSS back in....
Pull the instrument cluster, inspect the PSOM on the back of the speedometer for signs of leaking capacitors, broken leads, burned components.
A photo from Steve83:
The PSOM is the board on the lower left of the photo.
More info: What's a PSOM?
I HIGHLY suggest you put the original VSS back in....
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Thanks RLA! Any advise on the hard shifting problem? Honestly, thats more of a concern for me at the moment lol. I can deal with a speeding ticket, a destroyed transmission is something else all together! lol
Fleet Owner
Joined: Oct 2005
Posts: 20,780
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From: Kentucky
Yes, find out why the PSOM display is blank. The PSOM divides the signal from the VSS down to a usable range for the computer to determine vehicle speed/shift points. A blank PSOM means the computer is operating in Limp Mode, therefore full pressure is applied to protect the transmission.
Make 100% sure Fuse 18 is good. Measure it with a meter, do not rely on sight.
Make 100% sure Fuse 18 is good. Measure it with a meter, do not rely on sight.
Fleet Mechanic
Joined: Jan 2011
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From: 8600 ft in Colo
Most likely your problems have a common cause. The computer needs a good speed signal, from the VSS via the PSOM, to function correctly, or it will go into "limp" mode, which explains the blinking OD OFF light and the hard shifting. Don't continue driving it like this.
Edit: Looks like rla and I were typing at the same time...
Edit: Looks like rla and I were typing at the same time...
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Ok well I don't have a working meter at the moment but I did try to reset the POSM per the link you provided hoping that it would kick back on but got no results. I guess I'll pull the cluster after the wife gets home to see what I can find out through that. So, with a new VSS and AFTER I get the PSOM to work correctly this should solve the issue? Really appreciate all the help guys!
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Ok. New problem. Pulled the cluster and everything looked ok as per above. Put it all back in and now the truck wont start! What have I done?!
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Ok so I figured iut the truck will NOT start unless the fuel tank selector is connected to.the pigtail. So the truck starts now but speedo/odo are still not coming on. Im going to try to pull one out of a junkyard unless someone has a better idea. A little backstory. I got the truck from my mother in law who says she was told it was a pinched wire somwhere in the steering column that made it shift hard and that the speedo has gone out before but she just kept driving it with no other problems. I have no idea how long this has been an issue but I am going to get it fixed even if I have to take it to the dealership and get raked over the coals. This is the only issue the truck has. SO FAR
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Yes sir. Going to double check fuse 18 AND just to be safe get a brand new one as well. Mileage isnt really a concern. Truck has 280k+ on there. It cant get much worse lol. My luck ill get another faulty PSOM! Thanks for the help. Ill make sure to update when I get it fixed. Seems most people never bother. The posts just stop. Lol
Postmaster
Joined: Aug 2005
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From: Cleveland, TN
Ok so I figured iut the truck will NOT start unless the fuel tank selector is connected to.the pigtail. So the truck starts now but speedo/odo are still not coming on. Im going to try to pull one out of a junkyard unless someone has a better idea. A little backstory. I got the truck from my mother in law who says she was told it was a pinched wire somwhere in the steering column that made it shift hard and that the speedo has gone out before but she just kept driving it with no other problems. I have no idea how long this has been an issue but I am going to get it fixed even if I have to take it to the dealership and get raked over the coals. This is the only issue the truck has. SO FAR
If you find a blown fuse, there is a possibility this diagnosis is somewhat correct to a point.... There are three wires that run up through the shift lever to the OD cancel switch, these sometimes break right where they come out of the lever and pop fuses... The plastic shroud on the column comes off in two pieces, (top and bottom) you will need to remove them to see where the wires may be broken... It would be best to replace the shift lever, but if you're cheap like me you can repair the wires with solder and heat shrink tubing... Tape will not last so don't waste your time or fuses..
Fleet Owner
Joined: Aug 2005
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From: Easton,Ks
Just get one from a salvage yard, just get a non tachometer cluster (they cost less) for about $30.00. Any cluster from 1993-1996 will do (1992 was a little different).
Take out the PSOM and put it in your cluster.
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Ok. So turned out there was a bad fuse that looked fine. I replaced the fuses listed above and lo and behold everything came back on. Put it all back together and test drove it about 10 miles alltogether. No hard shifts and no flashing OD light. Time will tell if the new VSS fixed the hard shifts.
I did pull the column shroud and inspected the wires. Without completely taking them out from what I could see everything looked just fine. No pinched, discolored, or bare wires present. I guess we will see if it happens again or not. Thanks a lot everyone!
I did pull the column shroud and inspected the wires. Without completely taking them out from what I could see everything looked just fine. No pinched, discolored, or bare wires present. I guess we will see if it happens again or not. Thanks a lot everyone!