iv'e read a lot of the post on this prob with the push button systems mine will go into 4lo but when i put it into 4hi the light blinks for a sec or so and then kicks back to 2hi its 1995 lt iv'e read some post with the same prob as mine but no answers if 4hi works does that eliminate the vacum system pl help.

 

This sounds like a failing transfer case encoder motor. Have a read through THIS THREAD. If you have an OBD2 DLC (diagnostic or data link connector), then follow the information in THIS THREAD for checking the TCCM codes.

 

some detail to my prob when i push the 4ih button no lights or sound nothing at all then when i but it in neutral and push the 4hi button thats when it blinks and clicks and goes back in 2hi and like i said the 4lo works.

 

As it seems you have missed my previous post, please have a look above. The threads linked to will aid you in checking for stored codes in the TCCM. If there are stored codes, please list them for us. If there are no stored codes, please let us know and we will work from there.

The checking of the codes is the first step in the diagnostic chart for this problem.

The next step is to disconnect the TCCM wiring harness and inspect the connection for bent pins or corrosion. If either are present, repair the damage and retry the 4wd system.

If no corrosion or bent pins are present or if after repairing the damage, the problem persists, you must then back probe pins C4 and C5 on the TCCM connector with the ignition on. If either has battery voltage (~12V), then you have a wiring problem (could be a problem with the wiring or a problem in the status lamp switch on the dash).

If you do not find battery voltage at these two pins, continue with the following. Back probe these same connections, C4 & C5 with the ignition on. This time, press the 2HI and 4HI buttons. You should now have battery voltage at these two pins. If you do not, then there is a wiring problem or problem with the switch. You then must measure the resistance of the wire running from the status lamp switch connector terminal B to TCCM harness connector terminal C4. Also measure the resistance of the wire running from status lamp switch connector terminal D to TCCM harness terminal C5. The resistance value should not exceed 1 ohm. If it does, then a wiring fault is present and must be repaired (run a new wire). If not, then the status lamp switch should be replaced.

The next step would be to measure the resistance of the following pins in the TCCM connector to ground: C10, D10, D12, and D13. The resistance should be no greater than 2 ohms. If the resistance is greater than 2 ohms, then a repair to the ground must be made. If they all measure less than 2 ohms, then the Diagnostic Chart lists the repair as "Replace the TCCM". But this is only true if you get to this point.

This seems a bit difficult to follow, but I cannot get a clear print of the diagnostic chart. I will see what I can do for the future.

The wiring you will be dealing with are colored as follows:
Status Lamp Switch:
Pin A: Pink
Pin B: White
Pin C: Pink
Pin D: Gray / Black tracer
Pin F: Dark Green / White tracer
Pin G: Purple / White tracer
Pin H: Tan / Black tracer

TCCM Connector:
C4: White
C5: Gray / Black tracer
C10, D10, D12, & D13: Black