97 4x4 4 door

New vacuum lines and new transfer case switch. 50 inches of vacuum from motor and checked all Ts. I checked on the accuator side in 4hi and only 5 inches. But if I run straight from motor to accuator under battery it engages fine. Is it the NEW dorman transfer case switch that is faulty???? I found the vacuum hose routing and it is correct. Or am I missing something??? Thank you

 

50" of vacuum must be a typo, usually it is less than 20" at idle.

If all of your vacuum lines are infact routed correctly, either the vacuum switch is defective, or there is a leak in the vacuum line to the actuator, or the source line. The actuator needs to have manifold vacuum in 4WD HI & LO and zero vacuum in 2WD.

 

LOL reading gauge wrong. Yeah 20"yep just because switch is new dont make it good. Will replace switch this afternoon.

 

YES IT DOES. I double checked all lines. I replaced Dorman switch for another. Still getting about 2-3 inches in the accuator line just in 4 wheel drive. 0 in 2 wheel.
Like I said if I bypass switch and run from manifold to accuator it works fine. OK NOW let me ask. What flips the ball on the tranfer case switch???? Ball rides on???? Is it done ELECTRONICLY?????? Im missing something Ahhhh encoder motor

 

This might help: the 4x4 vacuum thread. - S-10 Forum

 

Thank you. A shift fork must engage the check ball under TC switch. Its done by encoder motor??????? I have the 3 button 4x4 switch all lights works when I run HOT from manifold to accuator. Maybe a fuse is blown not allowing encoder motor to run shift fork??????

 

Good write up for first gen T series vehicles, but it does not apply to second gen T series vehicles, (like the OP's vehicle).


Linkage in the transfer case depresses the ball when the encoder motor performs a mode shift from 2HI to 4HI. It remains depressed in 4LO, and releases in 2HI. If you're seeing 2"-3" at the actuator in 4WD, and a drop to zero in 2WD, you need to recheck the lines on the switch. Unplug the vacuum connector from the switch. Start the engine and identify which line is the source line from the engine. Remove the vacuum switch from the transfer case. One of the ports on the switch should hold vacuum. The other two ports should be connected to each other. The vacuum source line from the engine goes to the port that holds vacuum. Next, manually push the ball in. The vacuum source port will now connect with one of the other two ports. Connect the actuator vacuum line to that port. The remaining port is the vent line. It runs vertically to the transfer case vent, tees with another line, and then runs up the transmission dipstick tube, with a filter on the end. Post your results.

 

Thanks will report result tomorrow. I did use the chart that shows the 3 ports.

 

Red Sled - if you are using the org. factory three port boot that slides onto the ball switch, one or more of the holes could be oval due to dry rot ect. causing a slight leak. the one on my toy was that way and losing vacuum. at the time I was unable to buy a replacement so I plugged the lines directly to the switch

 

No clue where that chart came from. Could be Haynes or Chilton for all we know, that's why I explained how to figure out which port the lines attach to on the switch.