Hey all,

Driving a 2004 4.3L 2Dr Blazer 4x4

I've seen a few similar topics but not seen quite this exact situation. Bought this car used and thoroughly tested all 4WD options; everything was kosher. However, this new problem starts similar to the way some of the older topics about this start: I press the 4 HI button while in gear and nothing happens. No light, no differential lock, nothing. Same situation trying to go to 4 HI if I'm in neutral.

However, if I'm in neutral, I can shift into 4 LO (light for 4LO blinks then goes solid, differential locks, big change in torque/speed ratio). If I try to shift from 4 LO to 4 HI, both the 4 HI and 4 LO lights blink, but it will then shift into 2 HI (2 HI light goes solid).

From the search, it seems I may be looking at a loss of vacuum pressure. Someone also mentioned a $650 [] fix in another thread. Hope this isn't the case for me. Can anyone shed any additional light on the subject? Thanks!

 

Hey just my opinion but I would start with something simple I started the tread which I think is right below yours. It was concerning my transfer case. Even though it is a little different problem I would try this first take a small standard srewdriver at the bottom of thetransfercase swith on the dash andgently pop it off.Then slowly pull it outmaking sure not to bend, break or pull out the wires.Check for any wires that have shorted out. Then using a multi-meter or a circuit tester which you could probably rent from any auto parts store if you don't either of them and test the wire coming into the switch. This may not be your problem but when Kyle told me to check it also found out than because the lights were not work meaning the switchneither was 4Hi because with out the light being eluminated the 4hi would not engauge as I though it was working but even though I had been 4 wheeling I had not used 4 hi in a few weeks. Like I said this may not even be close but its worth a shot before you start dumping a ton of money into it. After all the more we spend in repairs the less we haveto play with. Hope this helps.
P.S. read my thread as Kyle explained about the wires.

 

Thanks 99, I'll look into this as a possibility. I think the problem is mechanical in nature, not electronic, but it never hurts to check!

 

As expected, no shorts. Wires are all passing current. Does anyone know what the next steps are for me?

Thanks for trying 99!