1992 ford explorer 4x4
4 door, 4.0L, automatic OD

Hi, a friend just gave me his old 1992 ford explorer, had to fix several things with it.. but have a few items i was hoping some of you might have come accross and save me alot of diag. time.

1. Tach not working stays at 4krpms unless engine is rev'ed and then bounces up a few hundred rpm's, when ignition is shut off, tach goes to "0"

2. Interior lights will not shutoff, have cleaned and checked all 4 door switches, and disconnected switch for rear glass no change, also made sure dimmer wasnt set.. is there a switch also for the gate itself or just the glass?, and or possibly a relay..

3. oil pressure gauge not working (related to tach?)... suppose i should check connection at sending unit :)

4. 4 wheel drive not working, when switch is pressed no indicator light or anything... checked fuses etc... guessing porb. faulty elec. shift motor?

5. over drive not working at all... tansmission shifts fine F/R.. shifts nicely when driving, no hesitation.. but just doesnt go into OD.. suggestions?

Thanks ahead of time!!
By the way, ment to add explorer has been sitting for 2 yrs... but OD and 4x4 problem where the reason he stopped driving it.

I will comment on what I'm familiar with:
4) That could easily be a faulty shift motor. It's quite common. Do a search for cleaning shift motor or similar and you should find a lot of information about it.
5) No 4th gear could either be a hydraulic/mechanical fault in the transmission, or it could be an electrical/sensor fault in the EEC-IV system. Because it's easier/cheaper to access, I'd start by checking the electric 3-4 shift controls before worrying about the internal transmission parts.
a) Start with the EEC-IV self-tests (www.dalidesign.com/hbook/eectest.html). Resolve any codes that come up. When you get pass codes for all three tests, if 4th gear isn't resolved, then proceed to b
b) Obtain a wiring diagram. While monitoring voltage drop across 3-4 shift solenoid, perform output state test (refer to eectest page above). Voltage drop should alternate between battery voltage and ~0 V as the solenoid changes state. This tests to see if the computer "can" tell the transmission to shift into 4th gear.
c) While monitoring voltage drop across 3-4 shift solenoid, perform road test. At appropriate speeds, you should be able to see the computer tell the transmission to shift. This tests to see if the computer "chooses" to tell the transmission to shift into 4th gear.
At this point, if all electrical tests are passed (the computer definitely tells the transmission to shift, but the transmission isn't responding), then the fault is almost certainly hydraulic/mechanical (Clogged screen on the 3-4 shift solenoid, sticky valve body valve, etc).

is there an aftermarket sterio in your truck cuz if their is then maybe when the old owner put the trim back on they didnt plug the 4x4 connector back into the panel. Grab the top right hand corner of your trim and give it a yank and peer in to see if its plugged in (theirs screws at the bottom of the trim so dont pull too far)

I think their a switch for the gate cuz when i open my gate the light turns on (mines a 92 as well)

Who needs a tach??? I dont think my overdrive works either and who need oil pressure???

There is indeed a switch for the gate. It is wired inside of the drivers side latch. You will need to remove the rear hatch trim to access it.

maybe the switch for the interior lights is broken causing the lights to stay on

As regards your trannie issues: To Mr. Shorty's post I'd add that the 3/4 shift solenoid has a screen that is easily plugged it is so fine. If the screen plugs up... no 3/4 shift. A COMMON problem. Fixed with the trannie in the vehicle. Drop pan, drop valve body, clean screen, replace. (assuming of course that IS the problem).