Well my truck spent 7 weeks at Mr Transmission because of a speed sensor code, they replaced the speed sensor 3 times and I've even removed my super chip. My tires and wheels are factory size, so I give up as to why its still throwing the speed sensor code. This is for an E4OD transmission on a 98 F150 4x4. Does anyone know of any TSBs or have had a problem like this?

 

Ummm, you know your speed sensor is on the rear diff right? Did they change the tone ring in the diff?

Adrianspeeder

 

This being a 4x4, the vehicle speed sensor should be located on the transfer case. What code are you getting?

 

Some people forget that a bad wire will set the same code as a bad sensor. Someone needs to check the integrity of the wiring to the speed sensor.

 

Yeah the speed sensor is on the transfer case output housing for my truck (unless there is another one that I haven't found or noticed).
I'm not exactly sure the exact code (they didnt tell me), but I was told that the speed sensor was reading 6-7mph faster than the truck was actually going which is causing it to throw a code. They replaced the sensor three times so I know its not the sensor. The problem only occurs when I drive on the Interstate. If I drive around side streets I never have a problem, it only happens when I drive on the Interstate. After I get off the Interstate the line pressure will shoot up to 100% and cause shifts that are too hard. So whatever the problem is, its only happening when I drive on the Interstate. Beyond taking it to the dealership, I don't know what to do.

 

Somebody might have put the wrong plastic drive gear on the end of the speed sensor, causing an erroneous vehicle speed signal. There are different tooth counts for the VSS drive gear, depending on gear ratios, vehicle application, etc...You really need to find out what code the PCM is setting, though.

 

A wrong plastic drive gear would explain why it was getting a false reading on the speed. The people at Mr Transmission are idiots, but they were fair to me. Would a regular OBDII scanner pick up the code? The O/D light is not flashing so I'm not sure if the OBDII would pick up the code or not.

 

All powertrain-related codes are stored in the PCM. Whether you can access them or not depends on your scanner. The cheaper ones may not read transmission-related codes.