Erratic Speedometer and flashing O/D light

[95xploder]

Last night I noticed my speedo was bouncing around a bit from 55-60 mph on my 95 sport 4.0 4x4. Today, after about 30 min of driving, it really started acting up. Sometimes, while doing 40 or so mph, it will drop to 0 and stay there.

Now, the O/D light has started flashing (12 times if that means anything). It always occurs when accelerating from a stop. The speedo stays at 0 while I accelerate and the rpms climb to about 3000 (normally it's already shifted around 2000-2500). Then speedo decides to work, jumps to 30ish, the tranny shifts hard, and the OD light starts flashing.

From what I've read on this web site so far, I'm lead to believe that it's not a transmission problem, but speedo problem. Something about the transmission relying on the speed sensor to calculate shifts.

I'm I right and if so, is it as simple as replacing the speed sensor, or could there be any other underlying problems as well?

Your thoughts?

Thanks

 

[jared ajlouny]

i think its a tranny problem if the OD lighht is flashing. however a few weeks ago i had a problem with my speedo like you are saying, but none of my other guages were working either. check all of your fuses, i think # 11 fuse went out on me. check that.

 

[Jason_25]

Inspect the VSS for loose or frayed wires. You may also want to remove it to check the gear teeth at the end. If you don't see anything wrong, replace it. It's most likely not the transmission itself.

 

[Opera House]

In that year they eliminated the mechanical speed governor that set the shift point for 1>2. It was always used for some higher gears. Think you just have a VSS problem and you just might try unplugging and connecting the electrical connector to clean the connection. VSS is at the back drivers side of the transfer case near top.

 

[95xploder]

Follow up-

I pulled the VSS. The plastic gear on it was damaged. Some of the teeth were very badly worn causing it to malfunction. I replaced the gear ($5.50) and replaced the sensor just to be safe ($35.00).

Problem solved!

I also checked with a Ford mechanic and found out that the gear inside the transfer case that drives the gear on the VSS is brass, so I belive that the gear is probably ok. I drove the X for a few days and pulled the sensor again to check the gear out and found no sign of wear.

 

[daniel cauchon]

Any pics or where and how it looks....I have the same prob for at least over a year..now...bounce from 55 to 60 and I feel I m going slower then its say realy.

tx

 

[95xploder]

No, sorry, no pics. If you want to check the sensor out, it's pretty easy. Find your tranfer case. On the backside of it, the VSS is the topmost sensor. Remove 1 nut and the sensor comes off. It's high enough up on the case that you shouldn't even lose any fluild.