I was given a '99 LS 4x4 w/ 152k. I tried engaging the 4x4 but non of the lights are coming on and nothing happens. Fuses are ok. Where should I start?

I pulled the panel and it's clean. One of the two dash lights works, so it's getting power. None of the push button lights are on and I don't hear anything engaging.

Ok. Now the ATC / 4WD fuse under the hood is constantly blowing. I hear a relay click a few times on the passenger side and then the 20amp blows. The fuse blows while the vehicle and ignition is off.

On my 3rd fuse, it didn't blow right away. I was able to turn the ignition on to see the push button lights come on. I turned it over and then the fuse went again. The 4WD fuse on the inside panel is fine.

I did a quick search and it would seem a '92 blazer had the same problems relating to the actuator. I'll look into this. Other then that, any ideas would be great. I'll more then likely buy a Haynes manual today and poke around for a bit.

 

Remove the passenger side kick panel and inspect the electrical connection to the TCCM. If any corrosion is present, clean the contacts and apply some dielectric grease and see if the ATC fuse holds. If that connection looks good, the next step would be to disconnect the electrical connections to the encoder motor. Same thing here, inspect for corrosion and apply some dielectric grease to protect the contacts.

 

I'll look into that tomorrow. I put a 25A fuse in place of the 20A and 4x4 engages fine.

 

Generally one step up in fuse rating is not going to cause harm to the system. It is not something you should do as a permanent fix though.

 

I can engage 4L but 4H seems to get stuck and all of the 4WD lights go out. It was not doing this at first yesterday. I spent most of today doing a full tune-up.

No codes. SES light is off now due to fixing a vacuum line issue and cleaning the MAF. It's shifting fine now that the MAF is spotless. Just have the 4WD issue to deal with now.

 

I hated that kick panel. I hear a lot of clicking near the TCCM as soon as a fuse is placed / blows. I'm assuming it's related.

Two questions:
1. Where's the encoder motor? The Haynes manual for the Blazer is vague.
2. Where are the turn signal flashers located as I hear it in the same location?

 

The encoder motor is located on the side of the transfer case next to the front driveshaft.

The flasher is located behind the glove box. Have a look at this thread:
Where is the turn signal/hazard flasher 1998 Blazer

 

Alright, thanks.

The TCCM had corrosion in a few spots. I cleaned it as much as possible but it still has the same problems. The 25A fuse holds until I try switching into 4H (for the most part). I'll be looking into in more after I travel back to Chicago.

 

I am having somethin simalar. My 99 Blazer has slipped into 4H twice. I put it back to 2H. I was told maybe a vacum leak?

 

I had to fix one vacuum line which had imploded and split open (if that makes sense). A lot of the remaining lines I've checked are dry rotted. The vehicle is 10 years old, sure, but some of the lines look like they're 20yrs old.