[cannanballz]

I have learned a lot from this forum over the years and have just created my own account. Thank you to everyone for the knowledge and I hope I can return the favors.

I am hoping someone can give me a little guidance on a speedometer/odometer issue I’m having with my van.

2003 E350 w/ 7.3, 4R100 w/ 90 or 91 Bronco Transfer case. Has a Ujoint 4x4 conversion done 2 previous owners ago so I don’t have much information on that part of it.

I recently lost speedometer and odometer function and now have rough and erratic shifting because of the lack of speed signal I assume. Have P0500 code. OD light is flashing.

Plugging into my computer I get no Output Speed signal either. I do however have an accurate speed signal when reading the two front and one rear diff ABS sensors.

I changed the front and rear speed sensors on the transmission but has not changed anything. Also changed the rear diff sensor just in case but still nothing.

I did a continuity test from each of those sensors to the PCM plug and had the following: (Not 100% sure I have the correct pin out diagram but seems right)

-Rear trans sensor - continuity to Vehicle Speed Sensor+ (pin 58, Circuit 679, GY/BK) - no continuity anywhere else

-Front trans sensor - continuity to Turbine Shaft Speed Sensor (pin 84, Circuit 970, DG/WH) - no continuity anywhere else

- Checked rear diff sensor and found no continuity to any PCM pins (guessing that goes through the ABS module instead?)

I just checked the 2 old trans speed sensors with a multi meter and seem to be getting the expected AC voltage out of them so they were probably fine to begin with.

Front sensor is a magnetic pick up and rear sensor is a plastic gear style.

I think that’s everything I’ve done so far. Oh yeah, and I swapped the alternator in case it was back feeding power.

Any advice as to where to go next would be greatly appreciated. I have an email in to Chris at Ujoiunt also to see I I may have a "Dakota Box" that deal with the VSS's.

Looking at swapping the PCM if nothing else. Would a gauge bad cluster cause the PCM to not get a speed signal? I have some donor vehicles I can pull parts from if needed.

Thanks!

 

[John in OkieLand]

Would the manual be of any help?


1999-2003 Work Shop Manual
.

 

[klhansen]

The VSS on the rear differential goes to the instrument cluster only (not the ABS module). Follow the Grey/Black wire from the sensor up to Connector 219 (under the dash on the left side very close to the parking brake switch, then from there to Pin 7 on connector 220A on the back of the instrument panel.
It's likely you'll find a break somewhere under the truck that's preventing the signal from reaching the speedometer. If you find continuity there, it may be a problem with the instrument cluster itself.

 

[cannanballz]

Would the manual be of any help?


1999-2003 Work Shop Manual
.

Thanks John, certainly a great resource. I'll check them out.

 

[cannanballz]

The VSS on the rear differential goes to the instrument cluster only (not the ABS module). Follow the Grey/Black wire from the sensor up to Connector 219 (under the dash on the left side very close to the parking brake switch, then from there to Pin 7 on connector 220A on the back of the instrument panel.
It's likely you'll find a break somewhere under the truck that's preventing the signal from reaching the speedometer. If you find continuity there, it may be a problem with the instrument cluster itself.

Thanks klhansen. I'll take a good look at the wire run you mentioned. I disregarded the rear diff sensor early on since I was getting a good speed reading out of the fronts and rear abs sensors on my computer. Maybe I was off base on that assumption? Won't have a chance to check things out until later today but will update if I find anything.

 

[themule67]

Last time that I had the same problem on my 95' it ended up being the instrument cluster sent it out to a company called RT Grim electronics I believe, they are out of PA. great people I overnighted it to them they had it repaired the day they got it and overnighted it back to me. My cluster ended up having 4-5 cracks in the circuit boards that was about 8 yrs ago haven't had that problem since.

 

[cannanballz]

I think I have figured out my problem. The rear speed sensor on the transmission, really on the transfer case right before the rear driveshaft wasn't working. Jacked up the rear end and tested all the speed sensors for ac output while in drive with the wheels spinning. Nothing coming from that one although sensor was new, other two were putting out. The sensor has a little plastic gear that meshes with another one inside the case. I reused the old gear and clip with the new sensor since it didn't come with one. It appears the inner part of that gear got rounded out and was slipping on the rectangular shaft of the speed sensor. Sensor would read AC voltage when out and spinning by hand but not when installed. Messed around with the clip to get the gear as tight as possible, reinstalled and started getting AC output. Plugged the sensor back in and the speedo started working! Both in the cluster and on the computer. Test drove and the speedo is a little jumpy at times, still causing some rough shifting, but was working, ODO too. Getting a new gear from Ford tomorrow and will confirm and update once installed. 🤞

 

[cannanballz]

Installed the new gear on the transfer case speed sensor and everything is working great now. Hard to see here but the old one was definitely rounded out a bit. $6 part even at the dealer.
old one here:

 

[cannanballz]

 

[cannanballz]