Speedometer problem: 1997 Ford Explorer Sport 4X4. Speedometer drops to zero after a few miles. May or may not come back online right away, but always does after being parked for a while. Checked the speed sensor plastic gear. It looks fine. Checked the Speed sensor with an Ohm Meter. It opens once per rev. Replaced it anyway. No help. From what I can see, the speed sensor gets voltage input and interrupts it once per rev. That signal goes to a solid state unit in the instrument cluster. I would think if the solid state unit were bad it would quit working all together and not drop in and out??? I did have the instrument cluster out to replace some bulbs recently, but the problem started a few weeks later?? Could it be just be a bad connnection at the cluster? Anyone out there have this problem? I hope it in not in the transmission. It is a fresh factory overhaul. One other thing, I noticed transmission fluid was inside the old speed sensor as a few drops leaked out when I turned it downward. There is no seal where the shaft goes in. Only an Oring around the outside. Do I have the transmission over serviced and the fluid gets in and shorts the signal?? I am stumped so far. Any help would be appreciated!

Bennie Williams

 

I'd try changing the sensor if its not to $$$

 

All ready did that, no help!

 

I have 96 Explorer XLT does the same thing like you already replaced the sensor, it is driving me crazy. It will be working and next thing you know it drops to zero. Other instruments work just fine.
Anyone with ideas beyond replacing sensor please let me know.
THX,
Flatout[:@]

 

To FLATOUT: Seems like you and I are going to have to figure this one out on our own! We both need to know if the speed sensor keeps turning when the problem occurs. I am gong to drive mine around the block unitl it drops out, then pull into the shop and pull out the sensor and turn it at a slow speed with a drill motor. If it stays at zero, we will know it is not the sensor or the gear that drives it from inside the tcase/tranny. If it does come back on line then we have an internal tcase/tranny problem...UGH!

I truly feel the problem is between the sensor and the solid state unit in the cluster. There are several connectors before it gets to the cluster. Any of these could have a weak connection that would cause the signal to drop in and out. I will let you know what I find. Please let me know if you figure it out.

 

The exact same problem happened here on my 96 Explorer Limited, approx 128K. Sometimes it'll work and sometimes it will not. On the bright side, at least "I'm not putting any milage on the vehicle" when it's not working. I suppose I do need to get this fixed ASAP but don't want to spend big $$$. Argh!

 

I have a Ranger that had the same problem. I went to the dealer and after about an hour I got the right part. Seems that there are several sensors attached to the tranny. Anyway, the one that worked for me is the sensor that is attached to the upper side of the rear end differential. That is the one that caused the speedometer to magically start working again. I believe the Explorer and Ranger are similar. Give it a look see. Also, there was a leak of oil around where the sensor inserted into the differential. Good luck!

 

I have proven that the problem with mine dropping in and out is not the sensor. i drove it until it dropped out, pulled in the shop, quickly pulled the sensor and turned it with a drill motor.....speedo worked fined. quickly re-sintalled it and dorve off....no speedo!
again, the plastic gear is fine....either there is an internal gear driving problem in the transfer case or a problem in the electrical connection from the sensor to the cluster and speedo needle. i hope it is the later. will let all of you know if i ever figure this out. i see alot of us have the same problem. i am going into insrtument cluster next to see what device there takes the signal from the sensor and converts it into needle movement. there are also at least 2 physical electrical connections between the sensor and the cluster.

 

Sorry I was away so long, but I solved my erratic speedometer problem today.
I pulled the instrument cluster to replace a burned out instrument panel light.
I found there is a tiny, tiny crack in the printed circuit track on the back of the instrument cluster, It is the printed circuit that provides a path from where the speed sensor wire input is located in the har wired gang connector and the solid state unit that "drives" the speedometer needle!

Email me at joel.bennie.williams and I will send you pics of the fix!

I patched in a tiny gaged copper wire between the two points and put it all back together.
WHAMO...the speedo now works ALL THE TIME FLAWLESSLY! It was my printed circuit all along!

ps: I did also have the flashing 4wd lights. So far, they have not flashed anymore!

 

My email jennivic605@gmail.com
Replaced bulbs, cluster, still nothing