I'm having a problem with my 4wd on my '92 ford explorer. it is either the vaccum module or the electronic shift module. the button doesn't work, for 4WD or Low Range. It doesn't even light up. I need some way to bypass this manually if anyone can help.

 

There is no relation between 4wd operation and vacuum on your '92 ('95 and '96 Explorers used a vaccum system to operate the front axle disconnect).

Usually when the system doesn't respond to the buttons, there's a problem with the shift motor (dirty/sticky and it won't turn or similar). Sometimes tapping the shifting motor with something will free it up. There are a couple of places on the net that describe how to take it apart and clean it up, too (therangerstation.com and explorerforum.com).

As for a manual bypass, it's not very convenient, but you can take the shift motor off and rotate the shaft by hand using a pair of vise grips or similar.

As common as the shift motor is, I'd start there. If that isn't the problem, then I'd look at the switches and the electrical connections (my '92 wouldn't shift one day, so I jiggled the connector and the shift module and the system worked just fine, I guess there was a bad connection right there).

 

There is no relation between 4wd operation and vacuum on your '92 ('95 and '96 Explorers used a vaccum system to operate the front axle disconnect).

Usually when the system doesn't respond to the buttons, there's a problem with the shift motor (dirty/sticky and it won't turn or similar). Sometimes tapping the shifting motor with something will free it up. There are a couple of places on the net that describe how to take it apart and clean it up, too

As for a manual bypass, it's not very convenient, but you can take the shift motor off and rotate the shaft by hand using a pair of vise grips or similar.

As common as the shift motor is, I'd start there. If that isn't the problem, then I'd look at the switches and the electrical connections (my '92 wouldn't shift one day, so I jiggled the connector and the shift module and the system worked just fine, I guess there was a bad connection right there).