Automatic Hub Lock Problem

[Bai]

I think i've traced the problem back to the little vacume pump on the passenger side fender. There is a 3 wire harness that plugs into it. With the
truck running the middle wire is hot with or without flipping the cab switch to four wheel drive or two. When I flip the switch into four wheel you would expect one of the other 2 wires to go hot, however they don't. I checked fuses and started to check under the dash but that is a cramped and unnerving workplace. Does anyone have an idea where to look...

Thanks

[mschn99]

Originally Posted by Bai

I think i've traced the problem back to the little vacume pump on the passenger side fender. There is a 3 wire harness that plugs into it. With the
truck running the middle wire is hot with or without flipping the cab switch to four wheel drive or two. When I flip the switch into four wheel you would expect one of the other 2 wires to go hot, however they don't. I checked fuses and started to check under the dash but that is a cramped and unnerving workplace. Does anyone have an idea where to look...

Thanks

90% of auto hub problems are due to a vacume leak. the first thing i would check is to pull the vacume line off right by the upper ball joint, and pull vacume on the hub assembly. see if the vacume holds. the second thing would be to make sure the electric vacum pump over the right fenderwell is working. if all that is ok, then start looking at the swich or solenoid......Marc