So I had a shop remove an aftermarket stereo and install a new one today. Now when I start the truck 4x4 hi/lo flash 6 times and repeats after about 3 minutes.. They said they didn't touch the switch wires or the 4x4.. I tried checking for power at the switch wires, nothing, tried disconnecting the harness from transfer case and checking for voltage, nothing.. what the hell is going on? How can a stereo install go to a 4x4 failure.. I find it hard to believe something went out magically between me driving from the parking lot to their garage. Any advice would help

 

1998 will have a 4x4 module behind the radio, it is basically just two relays in a box, maybe they moved or pushed on wires and it has loose connection now.

GEM(generic electronic module) is also behind the radio and is also part of the 4x4 system, this controls the 4x4 module and the dash switch, so GEM is flashing the 4WD light, because something is unhooked or broken.
GEM controls inside lights, wipers, door locks, 4WD, ect.............so it is fine if all you have is flashing 4WD light.

Pretty easy to push in a radio and unhook a connector, my guess would be thats the problem.

1998 4WD control diagram below

 

Ok, I'll do a little more digging in the dash, hopefully it's just something loose

 

Fuses to check

#3 in engine compartment fuse box

#9, 26, and 27 in cab fuse box

Any of these could have been blown by "radio work" and if blown would cause flashing 4x4 lights