Hi Im new here I just bought a 98 blazer ls 4wd. I have a problem, for no reason it will shift into 4hi. I searched but couldnt find anything. There is nothing that seems to trigger it, its hapend on the highway, parked and in a parking lot. Anyone have any ideas? maybe a faulty switch?

 

That dang search...

Well, lets start with the information you left out. Does 4LO engage and work properly? 3-button switch in the dash or 4-button? From there, diagnosis takes different paths.

 

3 button, 2hi, 4hi and 4lo all work. but it just randomly shifts from 2hi to 4hi.

 

Sounds almost like you have a faulty switch in the dash. You may want to try swapping in a salvage switch from a junkyard or eBay and see if that cures the problem.

 

I ordered a new 3 button switch. can I use the 4 button? I wonder if the 3 button switch doesnt work if I should try the 4 button, incase some one switched out with the wrong part. Or do the swithces have differant connectors?

 

Thanks For the INFO!!

 

If you have the NV233 transfer case, you cannot use the 4-button switch. They are not compatible with each other.

To determine which transfer case you have, you can either check the tag on the back of the transfer case for the model # or check your RPO codes. NP1 = NV233 (3-button) & NP8 = NV236 (4-button). If you do not trust the RPO code sticker in the glove box, put your VIN into the VIN Decoder at CompNine.com.

 

No Dice, I replaced the switch and still wont stay in 2hi. when it shows 4hi its still in 2hi. however it wont switch back now, with out putting it in neutral then shifting to 4lo and back to 2hi. any ideas?

 

Check out this thread (and the ones linked to at the top):
NV233 No Mode Switch (ie. 2HI to 4HI)

This should help you narrow down the problem.