Loosing VSS signal causing speedometer non-op and shifting issues

[exponic]

I have a 1998 Expedition Eddie Bauer with a 5.4l. The speedometer went out while I was on my way home from school and the transmission just wants to stay in first gear, check engine light came on the next day. So I've had to put it 2 on the gear selector so it will switch gears if I must drive it a short distance. When it is cold ambient temperature and a cold start, the speedometer will work for a couple of minutes and transmission shifts fine ( because it is receiving the speed signal) and then speedometer will decrease in speed slowly till it quits working. While it is starting to not work, if I let off the gas, the speedometer will raise in speed.

I scanned the computer and am getting a P0500, P0501, and P1500 all VSS codes. When cold, the scan tool data gives a good speed signal but will decrease just like the speedometer and voltage going to the PCM. I have torn into the transfer case and checked to see if the drive gear for the VSS is missing teeth/loose, and even replaced it just because. I have tested the VSS coming off of the transfer case and am getting a good signal (increasing a/c voltage at higher speeds) at ALL times. I tested the signal going to the PCM and when cold, it gets a good signal and then as it warms up the A/C voltage starts to decrease until it goes to nothing. I also tested the voltage going to the speed control servo/amplifier and the same result as the PCM, good when cold then quits when warmed up. I have replaced the GEM because I read about a TSB about water getting into the module from a leaky windshield and still nothing.

So I guess I'm running out of ideas and wondering if anyone has any insight or had an issue such as this before, maybe where a connector or ground has problems causing the signal to be lost or a known place where wires could have rubbed/pinched. I haven't noticed any other electrical issues or weird symptoms going on.

 

[exponic]

Has anyone seen where a bad instrument cluster will cause the PCM and GEM to not receive a speed signal?

 

[jrjr]

I have an issue with my 97 tach and have deemed it to be a bad cluster. In talking with a bunch of service departments I am told that you can drive just fine with no cluster so I would bet its not the cluster. As always though, watch out for Murphy.....

 

[exponic]

I found a link to what sounds like a very similar problem but there wasn't a resolution. http://expeditionforum.com/showthread.php?t=12817&highlight=speedometer+shifting
I sent a message to the poster so hopefully he will get back to me and I'll post on here once I get mine fixed.

 

[jrjr]

By the way, that driving without the cluster installed only applies to 97's and 98's....

 

[exponic]

I will try and disconnect the cluster tomorrow and drive it to see if that changes anything.
I'll give you an update tomorrow.

 

[alaskanexpy]

i'm betting the ABS sensor in the top of the rear axle housing. sounds just like the issues i was having with my excursion when my sensor went bad.

 

[SkyJumper]

Yes, if you have the ABS sensor on the top of your rearend housing, then try unplugging it, then taking the 1 screw that holds it in and take the sensor out. Once you have it out, try using degreaser on it and clean it up. And then reinstall it and plug it back up. Good percentage of time, the crap built up on the end of the sensor is keeping it from being able to read a signal off of the honing ring that is attached to your ring gear. If that does not work, try replacing it with a new one, they are rather cheap to replace.

 

[11:59]

today my speedometer stop working and now my truck is shifting funny I replaced the speed sensor on the rear no luck

 

[gteater97]

I currently having this problem also.....any solution

 

[SJBikesaws]

I have the same problem too, thats why I just joined this forum (98 Eddy Bower). My wife was driving it a few weeks ago, and the speedo shot up to 100 mph, then flat lined. Followed by bad shifting. Stuck my ODB2 scanner on it and I am reading P0500 only.

Changed the VSS sensor.

No change.

Changed the ABS sensor.

No change.

Pulled the transfer case apart, the gear was good.

chased the harness looking for grounds, none found.

Jacked the vehicle up, ran it in gear at various speeds and was able to get signal from both sensors all the way to the black and white wire in the back of the cluster, so I figured a bad speedo head. Changed it out.

NO CHANGE!!!!

I am in a dry climate, the car hasn't been wet for a while so I am doubting I got the GEM wet.

I keep seeing issues like this all over forums WITH NO RESOLVE. Whats the deal, the speedometer dies and you junk the vehicle out????

Any body EVER find the problem with theirs???? Feedback?

 

[SJBikesaws]

ALSO, before anyone askes.

ALL relays work, ALL fuses in tact. Voltage read to ALL. I spent another wasted day on that.

 

[gteater97]

I've got a 98 EB 2wd also and I ccan't find a solution either. I've replaced both sensors and traced wire after wire......im just lost at this point!

 

[ExpeditionLova]

bump im in the boat with yall ive been stuck for 8 months havent tryed rear diff abs

 

[ExpeditionLova]

lol man im in the same spot freaking blows

 

[Landrover 96]

Help

My expedition is having the same problems. I was driving it in the rain and the speedo would just start to either drop or jump around then my trans started to hard shift and jump around in gears and go out of gear. Also when I put it I'm park all of the 2wd and 4wd light came on and one or 2 other lights at the same time. Someone help and give us an awnser.

 

[Neonblack]

Eleven YEARS Later.... Has Anyone Solved this Issue...???
I have a 1997 Expedition with the Intermittent Speedo, bad shifting, odometer intermittent, etc etc
I did notice the rear window fluid squirter does not work...
I always run low on fluid a bit fast..
When I removed the passenger kick panel , I can see the relays, computers , etc
AND a Leaky Window squirter hose... Blue stain in the rocker panel sill plate chanel.... from the fluid... a red zip tie where someone tried to repair the hose..
Now I'm wondering if the line broke at the ecm, bcm, pcm.. whatever, there are three computers right there and the FUSE RESET BUTTON.. among other electronics.... Its like setting up your computer with the Garden Hose running through the mother board... Literally, Everytime the rear wiper squirter is pushed , it it spraying my computers and more..

Regardless, now I'm going through everything in there....

Has Anyone Solved this issue ?
I've read of Transmission shops installing New Transmission and still having the problems...

Any Help would be Appreciated...
Thank You....

 

[Billme]

I just got mine out of the shop, and it was the rear differential wiring causing PO500 code after they overhauled my transmission.. It’s circuit “A” going to the ABS control which sends a signal to the GEM, and then to the PCM.. It interacts with the VSS on the transmission..

 

[Billme]

Well guess what? It came back..But this time I did notice something..When we checked the signal, my speed was below 70, because I thought I had a tire balance problem.. So I had them rebalanced and went back up to 70 and 75.. Same shake, but I realized it has to be in the drive train, or rear differential.. There has been a weird rattling with the slightest bump, I not been able to find.. I jacked it up and found excessive in and out play on the driver’s side axle..
As long as I stay 60 or below, I seemed to be ok, but at higher speed with the shakes, I get the PO500..
I’m going to do one more run at high speed to make sure..
If so, back to shop.. I had them check this when I had the gear serviced but obviously they didn’t go into detail..
Lots of backlash as well as what I think is excessive in and out play on the DS axle..I’m thinking this vibe is effecting the tone ring somehow?

 

[nabil]

Not the same gen, but I had a speedo that played around randomly and a flashing O/D off light (trans in limp mode) after a rebuild. I had to change both the shaft speed sensor and its connector. Make sure the hole into which the sensor is dry and fully cleaned of any debris, and only apply oil on the sensor's o-ring. Also, the connector must be fully clicked and attached onto the sensor, and when replacing the connector, make sure it's the exact same shape, since I faced a huge problem in finding the same shape and found it on Temu of all places (it works perfectly fine). I used a Dorman sensor that works great. If the trans is in limp mode, the car might still drive relatively normal, but the trans overheats like crazy and burns off oil. Hope that helps.