93 Blazer 4WD- I can only get the 4wd indicator lights to come on if I press the selector in nuetral then both lights will blink then stay on, doesn't feel like the 4wd is engaging. It will not shift on the fly. After reading all the forums here, should I go to the trouble of replacing components or just install something like the posi-lok. Has anyone installed this kit, how hard was it and is it worth the money.

 

Hi, what do you mean by "posi-lok", if you are talking about replacing the vacuum/cable system for engaging the front axle to a manual type first you need to pin-point why the 4x4 isn't working. There are several things that have to happen to engage the 4x4, the TCCM, encoder motor/assembly and vacuum all have to be working - and the transfercase also needs to be operational. I would start with checking that the Transfercase or TC is working. You can do this by removing the encoder assembly, this procedure might/will involve removing the front driveline and front yoke on the TC. Once the encoder assembly has been removed you can use a 5/8" open end wrench to rotate the TC selecting rod. If you can engage the 4x4 at this point then your problem is either with the encoder assembly, TCCM or wiring.

There are so many things that it could be, I know I have been down this road. You can try resetting the TCCM, cleaning the connector to the encoder assembly, checking the TCCM for bad connection. If it was me, I would verify that the TC is working as it should be. One possible problem with the TC is flooding from a bad seal. The TC has a 2-way seal that keeps the tranny fluid out and the TC fluid in. When this seal goes bad it allows tranny fluid into the TC, causing it to be over-filled. One way to check for this condition is to pull the fill plug from the TC and see if you have any excess fluid. There are 2 plugs on the TC, one lower for draining and one upper for filling, both are 1 3/16" inch. I suggest getting that socket to make this job easier.

 

Thanks for the feedback. The posi-Lok, that's the brand name, I'm referring to is a kit that supposedly eliminates the vacuum control and allows you to select 4WD manually. It's a cable system that I saw posted on one of the forums on here but the posting looked more like and ad than something from a member. From what I've read, it seems these components break on a regular basis and I don't want to keep fixing something over and over if there's a better fix for it.

 

There are 18 pages in the '93 Service Manual refering to this kind of problem, way too numerous to put on here. There is an easy way to check the entire system thru the DTC codes. This will check your TCCM motor circuit, Encoder faults and Ram & Rom of the systems. Use the paper clip method and put one end in "A" of the DCL (top row, last hole from left to right) and "J" (bottom row, 3rd hole left to right or 4th hole from right to left) Turn ignition On ("don't start" !) There are only 4 codes, 1-4. If no codes flash at all, it says to replace the TCCM. I would check the wire connectors first to the selector switch & others. (most common cause) .

 

Thanks for the input. I'm beginning to think this system was junk from the day they built it. Wish I could have found one with the manual 4 wheel selector. That's ok, I'll fix it one way or another, never seen a bowtie I couldn't re-engineer if need be.

 

The vacuum operated 4x4 system is trash. Try to swap it for a manually-actuated one.

 

OK, I got the Posi-Lok installed and put on a new encoder motor. Now I have 4 Low but not 4 Hi. Can only be one of two things left, either it's the switch or the TCCM. Getting a new sitch in tomorrow, $33 bucks, praying it isn't the TCCM, thses things are hard to find. Anyone know where I can get one if I need it?