I have a 2003 Chevy Blazer 114800 miles with the Automatic transfer case . While I was driving my 4x4 service light came on. Never did it before. I was a 1/2 mile from destination. So I tried putting in 4hi. Did that. When I went to put it into 2Hi, it act like it tried. It went into 2hi blinking and back into 4 Hi blinking. Tried the same thing again. Samething. Turned the vehicle off and restarted. 4x4 service light didn't come back on still in 4Hi and I pushed the 2Hi button again and went back to 2Hi no problem. Parked it and when I went home, light didn't come on at all. I looked over some previous post like: https://blazerforum.com/forum/2nd-ge...at-next-88760/

This what gather: TCCM Does that stand for Transfer Case Control Module? Where is that? What is the BCM?

I guess the Advance Auto and AutoZone code readers won't read those codes?

Good places to start looking?

 

The TCCM=Transfer Case Control Module, is located behind the right kick panel by the passengers feet. BCM=Body Control Module. The TCCM requests information from the PCM, (Powertrain Control Module) and the BCM to determine if shifting the transfer case is permitted. The code readers at the auto parts stores can not access the data you need. You will need a scanner capable of accessing the TCCM to retrieve the DTC's.

 

This happened twice since and I could turn off vehicle and seemed it would just reset. Well, today it didn't. Was in this weeks snow storm, 4x4 work fine. I was less than a mile leaving my home this morning going to work. Tried to turn off and on and no reset. I thought I heard a faint click or clunk when it first went on. Any ideas of a fix? Or do I need to find a professional scanner?

 

Check the plug terminals on the TCCM to see if they are corroded, common problem.

 

It looks like it did the same thing like I described in my first post: "So I tried putting in 4hi. Did that. When I went to put it into 2Hi, it act like it tried. It went into 2hi blinking and back into 4 Hi blinking." The light also stayed out twice when I was driving so far. Do you believe the plugs need a cleaning?

 

. Does my symptoms sound like this could be the problem? Could you clean up the plugs and reuse?

 

I found that along with the TCCM contacts and connector being corroded/dirty, the 4x4 switch itself is a problem with an easy fix. Just need to take the the switch out, carefully split it open to expose the circuit board and then re-flow all the solder joints especially at the connector.

Sure fixed the problem mine had when it would often flash 2Hi, 4Hi, 4Lo.

Both of these are a $0 cost thing to try.

Also check the vacuum lines under the hood, left side up by the cowl. If you have not changed these lines, they will be slip, rotted, etc, and no longer holding vacuum.
Just get several feet of vacuum lines and replace all you can...one at a time.

Good luck.

 

Did your do like mine did as far as the flashing lights?

 

Ok, cleaned the plugs on the TCCM. I have noticed the bottom ones were mostly some corrosion there. Took for a spin around block. Felt good till light came on before getting home. Same problem. Will go into 4hi and Auto4wd, but when you push the 2hi button, the 2hi light blinks for a few seconds, then it switches to 4hi light and it blinks for a few seconds(you hear the TCCM click when going to 4hi blinking), then it goes to solid 4hi light. You hear the TCCM click again. Any help?

 

Oh yeah...had 4x switch lights flashing, would not go into 4Hi, just flash or sometimes it would, but then not into 4LO, just flash. Pulled the 4x switch out of dash, carefully took it apart and reflowed all the solder joints. Re-installed it and have not had a problem since.

If you have never soldered before this is not a good item to learn on. Should not be difficult to find someone that knows how to solder....look for amateur radio antennas near you; most "hams" know how to solder. I will offer to do this for you, but would mean you would have to ship it to me unless you are in Tucson.

And in my original posting about the vacuum lines, it was supposed to be "...they will be split..."....not slip...(brain tells fingers which keys to press but fingers do not always listen).