OK, so I am on vacation this week, driving my '01 E450 shuttle bus RV conversion. I am crusing along at 70, then I lose my speedo and the OD light is flashing. I get to the next town and run a code check, I get the VSS sensor code. I replace the rear one, nothing. I buy the OSS sensor for the trans. As I am trying to take the sensor out, it breaks, leaving the aluminum base in the trans with no way of getting it out. After taking ti to the local shop, they spent 4 hours under the bus trying to break out the sensor. In the end, a lag bolt and a prybar get it out. The culprit? a melted speedo gear. I discuss everything with my tranny guy, and since the trans is shifting through all the gears, just a little firmer, we decide to go on without the speedo. Here is my question- I have been told that it may be possible to tap into the rear ABS sensor on the rear diff and wire that to the oss plug at the tail of the tranny to get my speedo, ODO back and to get the trans to soften back up. I would like to hear your thoughts and ideas on this. It seems so far to be doing alright, but it shifts a little goofy now (particularly when downshifting and going into OD) and I would really like to have my speedo back. Thanks in advance. The drivetrain is a 7.3 power stroke with a 4R100 trans.

 

I can't get a speedo gear except from a dealer and I am traveling, so not really anyway to order one, and it is the weekend. Not sure why the gear metled in the first place, the guys at the shop seem to think it was due to a failed spensor the heated up or something. I have not driven with the e-brake on (has the driveshaft brake on the tail of the trans).

 

Speedometer gear melted? I think you need a new transmission technician. There isn't a speedometer gear in the transmission. The speedometer takes it's signal from the VSS.


Output Shaft Speed (OSS) Sensor
The output shaft speed (OSS) sensor is a magnetic pickup that provides transmission output shaft rotation speed information to the powertrain control module.
The output shaft speed (OSS) sensor is mounted externally on the top of the transmission case. The PCM uses the output shaft speed (OSS) sensor signal to help determine electronic pressure control (EPC) pressure, shift scheduling and torque converter clutch (TCC) operation

 

nope, no need for a new technician. There are some 4R100s that had a plastic\nylon gear in on the oss in the rear tail of the transmission. It is an oddball, but this is an E450 cutaway van, not a F450. The vans were a little different. Trust me, there is a gear there, at least a melted one. The tranny has a steel gear inside that it mates up to.

 

Did you ever resolve the melted gear issue on your vss? I just encountered this problem.

 

Yes, we were able to resolve the issue. We had to use a slide hammer and a good heavy screw to pull the gear out. Once that was done, you can just replace the sensor. I don't think the tailshaft gets enough fluid flow to properly cool the gear and eventually it will melt again.