95 Explorer drivability issue

[Micheal Robinson]

Ok im new to this forum but not new to the automotive industry. I'll put all that into details later. But to the point...

I have a 1995 Explorer XLT 4WD, with selectable low and auto four wheel drive. Had it for about a year and a half, nothing to complain about till the transmission started acting funny. In all my years I've never experienced this but it will shift hard (like a major shift kit installed) or slip really bad but will still move and other times shifts perfectly! And has been that way since we bought it. But as of yesterday the speedometer likes to work for a short time (about time to get to operating temperature) and then sticks to 50MPH. I read one post here about a bunch of different things it could be, and to clarify, mine has all options, cruise, tilt, a/c ABS. After reading said post im wondering now where to start? I've been in the automotive field for 15+ yrs and this is something I never experienced.

 

[Tedybear]

The 1995 Explorer uses a full electronic system to control the speedometer, cruse, pretty much everything. I would start at the transfer case and have a peek at things. Including the gear INSIDE the transfer case (that's where our problem was found to be with our speedometer) From the sounds of it, this is more like an electronics fail when things get hot. Considering how FORD tied all the systems in place, You have the same sensor wire going to the GEM module, Speedometer, the ECU, and the Cruse module. My gut feeling is that the sender is bad. This can be tested with a multimeter. What I did with ours, and this is risky!! I put all 4 wheels up on stands. I ran the engine in gear RWD only and had a pigtail that I "borrowed" from the local pick and pull yard the last time I was under an Explorer. The speedo sensor was unplugged from the main harness, and I had my pigtail installed and wired to the meter. In your case it should be at full temp so the issue presents. If the issue doesn't present, and the voltages run up/down smoothly on the meter at different speeds? It could be a wiring issue or a thermal fault in one of the modules. This is risky to do, as the engine will be running and the wheels will be spinning!! So use extreme care if you try this!!

S-

http://www.speedwaymotors.com/Tech/Testing-2-and-3-wire-speed-sensors.html

 

[gmanpaint]

Sounds like an intermittent VSS to me. Easy 5 min job.

Other thoughts are:
Check and make sure the ABS bulb is still working, by unplugging one of the fronts. If it doesn't light up, the bulb maybe bad, replace it. Once you confirm you have a working ABS bulb, and if it is on, check all 3 sensors. If one sensor is bad, the system shuts off, and the dash light comes on. If the rear sensor is bad, this could be an issue for the VSS, as it sends the pulse info to it. If that info is corrupt, the VSS can't do it's job properly.
The faulty (if it is) VSS can also mess with shifting as it has no idea what gear to tell the trans to be in. Limp mode will make the trans shift hard and act weird as well. Unhook the battery and wait about 5-10 mins before hooking it back up, next time this happens. Hopefully your O/D bulb is good, and it is not flashing. If it is flashing, your in limp mode.

These transmissions are weak, and overheat easily as they age. I pulled mine and installed a manual trans to be done with all the headaches.