[shadow1117]

Can I run any tune in 4wd or does it need to go into a stock position. 4wd did not work today, although the drive shaft would spin, no traction in front wheels. Didnt think to try it in stock till i got home... Just troubleshooting before i go to the tranny man...

[andrew]

Your hubs might have been sticking or the vacuum pump is not supplying enough to get them pulled in. manually engage them if you can.

[shadow1117]

OK so now the vents do not blow air, only through the defroster vents. It looks like thee fact that my 4wd is not engaging and the blower only works to the defroster would mean 4X4 vacuum solenoid is stuck open??? This is what I found in researching other forums. Can anyone confirm that this sounds right???

[907DAVE]

It means either you have a vacuum leak somewhere, or the vacuum pump is inop.

Check the vacuum lines that go to each of the spindles, they are prone to break the plastic fitting up on the bracket that holds them on the frame.

Also, check the fuses inside the cab, there is a 10 amp fuse that supplies power to the pump as well as a few other things, sorry cannot remember exactly what they were right now.

[Robert6401]

Dave's got you covered. Just wanted to make sure you understand that this has nothing to do with the tuning. It's a common mechanical failure. Personally, I unplugged the solenoid which feeds the electrically actuated hubs so I can use my truck in 2-lo. If I plan to use 4wd, I just make sure to manually engage the hubs.

[shadow1117]

After a bunch of troubleshooting, it turned out the power supply going into the pump was not hot. The wire must have been frayed and finally gave out. I ended up jumping the hot side of the connector to another power source and all is well... Thanks for the help...

[907DAVE]

Fuse good?

Glad you got it going again!