Vehicle Speed Sensor location?
Thread Starter
Joined: May 2007
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Vehicle Speed Sensor location?
I am having a speed sensor problem with my '91 B350 van. It will not go into overdrive or register anything on the speedometer. I have checked fuse 17 and the wiring to the overdrive switch and speedometer.The rear speed sensor has been replaced 10K miles ago so I suspect the vehicle speed sensor (part no. 56022075). Where is it located? I want to check for a loose wire or possible corrosion first before replacing the unit, and of course I'll need to find it to replace it too.
And to check the rear speed sensor, is there a simple multi-tester test that can diagnose it such as normally open, normally closed, or a resistance value that can be read between the two leads?
Thanks
PS. A wiring schematic to the unit would really be helpful too if anyone has it.
And to check the rear speed sensor, is there a simple multi-tester test that can diagnose it such as normally open, normally closed, or a resistance value that can be read between the two leads?
Thanks
PS. A wiring schematic to the unit would really be helpful too if anyone has it.
Thread Starter
Joined: May 2007
Posts: 7
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RE: Vehicle Speed Sensor location?
Thanks, a few more questions if anyone knows--
1. I assume it is the furthest thing back on the tranny on the driver side with wires going to it; is that correct? I took this out and it had a little drive shaft and a fluid seal around it. Assuming it generated voltage when spun, I ran it at 1700 rpm but got 0 volts output. Is this a telling result for this unit? Between the 2 contacts read infinite resistance (open).
2. I notice that there is a metal plate underneath this unit that is part of thetranny case that can rotate and be locked into 4 different positions; what is the relationship between this and the performance of the sensor?
3. Someone else suggested"it is adjustable by rotating until the speedo starts working". Do you think they mean simply rotating that plate? If so, since it was working fine previously with the plate in its current position, would rotating theplate make a difference with the existing sensor?
1. I assume it is the furthest thing back on the tranny on the driver side with wires going to it; is that correct? I took this out and it had a little drive shaft and a fluid seal around it. Assuming it generated voltage when spun, I ran it at 1700 rpm but got 0 volts output. Is this a telling result for this unit? Between the 2 contacts read infinite resistance (open).
2. I notice that there is a metal plate underneath this unit that is part of thetranny case that can rotate and be locked into 4 different positions; what is the relationship between this and the performance of the sensor?
3. Someone else suggested"it is adjustable by rotating until the speedo starts working". Do you think they mean simply rotating that plate? If so, since it was working fine previously with the plate in its current position, would rotating theplate make a difference with the existing sensor?
Van & CUV Section Moderator
Joined: Nov 2006
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RE: Vehicle Speed Sensor location?
1. According to your tests, the sensor is no good.
2. The 4 positions are to adjust for the 4 different sensor that can fit in there. A sensor with a smaller gear would need to be moved a bit closer to the tranny output shaft than say a larger diameter gear. That 4 position adjustment is a cam thatdoes this job.
3. This only works if the gear wasn't engaging to begin with, but in your case the sensor is no good so you can dismiss the "rotate it" advice.
2. The 4 positions are to adjust for the 4 different sensor that can fit in there. A sensor with a smaller gear would need to be moved a bit closer to the tranny output shaft than say a larger diameter gear. That 4 position adjustment is a cam thatdoes this job.
3. This only works if the gear wasn't engaging to begin with, but in your case the sensor is no good so you can dismiss the "rotate it" advice.
