HI, i just bought a 1990 B250 conversion van.Speedometer and Odometer are dead. From my limited research I'm assuming that the speed sensor is bad. I bought new one but I can't figure out how to get the old one off the transmission. I have removed the bolt that holds on the guard/cable retainer which also allowed the speed sensor to spin 360 degrees but it will not come loose.
I've attached a pic of the part I purchased, hopefully I didn't screw up and get the wrong part.
If anyone has successfully replaced their speed sensor and have any insight for me, I would greatly appreciate it.
THANKS

JOHN

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It just pulls out, there is nothing else holding it, except maybe some crud around the o-ring seal inside.
Get something under it like a putty knife and just work it out.

When installing the new one, take extra care to make sure the stem lines up with the center of the sensor. If they're not lined up, the sensor will not go all the way in, so don't force it or you will break it.

 

Thanks for the super-quick reply.
I have another question, probably one of many to come......

I noticed that the bottom of the new speed sensor, below the rubber bushing/o-ring there is a nut surrounding the center stem of the sensor.
Will this mate inside to the rest of the sensor inside of the trasmission housing? How will this tighten down? When I pull the old sensor out with a putty knife is there a cable of some sort that the new sensor will screw onto? If so will this come out far enough for me to screw it together?

Sorry for the noob questions, but I'm knida a noob. My Haynes guide only speaks of the old analog speedometer cable, not the newer electronic sensor speedometer.

I'm going to take another crack at this today.
Thanks in advance!!!

JOHN

 

The sensor is just a slip fit, there is no cable or anything else to disconnect. Think of a hex shaft being fitted into a hex shaped hole and that's basically what you're going to find in there. I wouldn't worry about the nut since it's dropping into a round hole slightly larger than itself.

 

So I had the wrong part...... I got the correct part from the Dodge dealer and replaced the sensor, but still no SPEEDO and no ODO. The dealer parts guys said it was an ABS speed sensor that happened to be pretty specific.

It does randomly jump all the way to 100+ mph and then back to 0 and I have tried flipping the cable (changing the polarity) just to see if maybe I had it backwards and it does the same thing both ways.

Any suggestions?

Thanks

JOHN

 

Are you changing the sensor on the tranny or on the rear axle? There's one on the rear axle only if you have rear wheel anti-lock brakes (RWAL).

Trace the wires from the sensor and look for signs of abrasion, or any place where there might be a short.