Is my entire drivetrain shot? Lights constantly flashing on dash

[FPGT24]

I bought my excellent shape 99 Explorer XLT for $1,200 about 3 weeks ago. I bought it knowing there was a major problem with the 4x4 system. Its the OHV V6 and 5 speed automatic.

When you start the truck up, the 4x4 cuts on and stays on and it almost feels as if its seized and it makes sounds like its half seized, and the truck usually will not move much in reverse and its lethargic when accelerating. after driving about half a mile, you can feel the 4x4 disengage and then right after, the 4 high and 4 low lights will blink together about 3 times. they will blink every 15 mins or so.

I had to unplug the 4x4 by pulling out the plug underneath the truck to stop the 4x4 from cutting on and staying on for half a mile or so everytime i start it. The guy i bought it off of said he replaced almost everything to do with the 4x4 system and nothing solved it so he got the ***** of it and sold it to me.

Anyone know what the problem with the 4x4 could be?

And heres where it gets interesting.......my bud Jeremy put in a head unit for me on monday and ever since, my parking lights come on as soon as the ignition is turned on and they will not go off till the ignition is switched off. also, since he did that, when i start the truck up, "4 WHEEL LOW" is displayed on the odometer and it stays on for about half a mile. This is with the 4x4 disconnected. Also, the "O/D OFF" blinks for about a mile shortly after i take off and the transmission shifts strange. O/D light goes off after a mile or so and the transmission begins to shift perfect. Does this EVERY TIME i start it up just like the 4x4 does the same thing. I think my friend screwed up some of the wiring because none of this happened before that.

Does anyone know what all these problems could be? Is my transmission going out?

 

[mr_valingo]

As far as the parking lights go, it sounds like he hooked the dimmer wire to the acc wire.

 

[Willcall]

You might want to check the GEM module (the black box behind the radio bezel). It controls the transfer case and can go a little crazy.

The parking light problem could be coming from a bad connection to the radio dimmer wire or possibly to the GEM too, as all that wiring goes back to the headlight switch.

 

[my98nnj]

Disable the transfer case. Search Brown wire mod. See if the problem goes away.

Somebody correct me if I'm wrong on that mod.