4wd randomly engages

jcoast · March 10, 2014

The issue I'm having is on a 2003 Silverado, 5.3 LS. Not long ago I had my PCM updated/reflashed and since then my 4wd-HI will randomly engage while I am moving at decent speeds. Once 4wd-HI engages, the only way I can get out of it is by going to AUTO then 2wd, but even then it will not work sometimes. When switching back does not work, I can feel 4wd-HI disengage from the front wheels, but the 2wd light will continue to blink and shortly after switch back to 4wd. It's been happening more often and I'm afraid it will one day switch to 4wd-LOW at high speeds and grenade my differential transfercase.

I've read that it could be the control panel, but when it happens all the lights continue to work and I am not getting any dash 4x4 service message. The other is the encoder, but before I spend the money and time I'd like to get some more opinions from those more knowledgeable and experienced than me.

Thanks

barry34 · March 10, 2014

Maybe a bad actuator?

Jachunter · March 10, 2014

Just paid $500 to replace my second bad actuator today. The problem starts as intermittent 4WD engagement and then it will not move back to 2WD.

You need to engage the actuator into 4WD every couple of months to keep it working properly is what Carl Black Mech told me today.

I joined this site today to learn how to change actuator myself next time. Good luck.

gmtech4 · March 11, 2014

The issue I'm having is on a 2003 Silverado, 5.3 LS. Not long ago I had my PCM updated/reflashed and since then my 4wd-HI will randomly engage while I am moving at decent speeds. Once 4wd-HI engages, the only way I can get out of it is by going to AUTO then 2wd, but even then it will not work sometimes. When switching back does not work, I can feel 4wd-HI disengage from the front wheels, but the 2wd light will continue to blink and shortly after switch back to 4wd. It's been happening more often and I'm afraid it will one day switch to 4wd-LOW at high speeds and grenade my differential transfercase.

I've read that it could be the control panel, but when it happens all the lights continue to work and I am not getting any dash 4x4 service message. The other is the encoder, but before I spend the money and time I'd like to get some more opinions from those more knowledgeable and experienced than me.

Thanks

ya dont go and throw parts at the computor controled t case ,,,,t case will not shift into 4 lo at speed ,,,,

you scan scan it for giggles and go from there ,no guessing

programming PCM has nothing to do with the TCCM

do not guess

CapitalTruck · March 11, 2014

Another instance in which I'm glad I got the lever actuated transfer case. Admittedly this isn't a very helpful comment.

gmtech4 · March 11, 2014

Another instance in which I'm glad I got the lever actuated transfer case. Admittedly this isn't a very helpful comment.

agreed !!!

unfortunately people have stated that they like hitting little buttons,,,,car makers have provided this ,,,,at a cost when it chards the bed ,,

gmtech4 · March 11, 2014

Just paid $500 to replace my second bad actuator today. The problem starts as intermittent 4WD engagement and then it will not move back to 2WD.

You need to engage the actuator into 4WD every couple of months to keep it working properly is what Carl Black Mech told me today.

I joined this site today to learn how to change actuator myself next time. Good luck.

second paragraph is out to lunch ,,never heard such nonsense in awhile lol

Coy9901 · March 12, 2014

This same issue happened in my 2006... Twice!

jcoast · March 12, 2014

This same issue happened in my 2006... Twice!

What did you do to fix it?

Coy9901 · March 12, 2014

What did you do to fix it?

I wish that I had better info on it. I sold the truck a few months back and now I drive a 14'. I had the receipts from the dealership also. I remember the first time that it happened I was driving on a lonely Hwy in the middle of Arizona. I drove it to a Chevy dealer and they replaced some sort of electronics ($600 worth). The next time it happened I was in my driveway. I thought that I was going to have to get a tow truck to get me to the dealer, because I was unable to get it out of four wheel drive. After I went into reverse, drive, reverse drive a few times it finally worked. I took it to the dealership the next day and they replaced the same electronics (another $600). At the time, I just paid it and went on about my life, so I couldn't tell you the exact details. I do know that that was my only problem with that truck for the 141,000 that I put on it before selling it. Sorry I couldn't be of any better help.

barry34 · March 13, 2014

The actuator is easy to remove and diagnos. Seach on here for procedure.

gmtech4 · March 14, 2014

The actuator is easy to remove and diagnos. Seach on here for procedure.

he should really scan it first instead of doing ^^^^^^^^^^^^ maybe get pointed in the right direction ,,,

please dont tell people what to do before any codes are posted ,,,they WILL get side tracked and may spend money on misinformation ,,,,we cannot do that unless 100% confident

jcoast · March 14, 2014

he should really scan it first instead of doing ^^^^^^^^^^^^ maybe get pointed in the right direction ,,,

please dont tell people what to do before any codes are posted ,,,they WILL get side tracked and may spend money on misinformation ,,,,we cannot do that unless 100% confident

To be honest, it costs me less than half to replace the encoder ring than it is to have it scanned by a dealer. If I am wrong, then I still saved $55, since it can only be one other thing.

On the other hand, I refuse to pay $100 to simply find out what's broken on my vehicle. There is no reason with todays technology that you should need a multi-thousand dollar calculator to recieve system errors/faults. Not only that, but it allows mechanics to falsley state what is wrong with your vehicle. rather than you knowing directly before you visit. It really should be illegal in this day and age.

Imagine if Microsoft or Apple charged you $100 to display error codes on your computer or phone. There would be riots.

Edited March 14, 2014 by jcoast

barry34 · March 14, 2014

he should really scan it first instead of doing ^^^^^^^^^^^^ maybe get pointed in the right direction ,,,

please dont tell people what to do before any codes are posted ,,,they WILL get side tracked and may spend money on misinformation ,,,,we cannot do that unless 100% confident

I didnt tell him to replace it, I was saying the actuator is an easy part to troubleshoot.

barry34 · March 14, 2014

To be honest, it costs me less than half to replace the encoder ring than it is to have it scanned by a dealer. If I am wrong, then I still saved $55, since it can only be one other thing.

On the other hand, I refuse to pay $100 to simply find out what's broken on my vehicle. There is no reason with todays technology that you should need a multi-thousand dollar calculator to recieve system errors/faults. Not only that, but it allows mechanics to falsley state what is wrong with your vehicle. rather than you knowing directly before you visit. It really should be illegal in this day and age.

Imagine if Microsoft or Apple charged you $100 to display error codes on your computer or phone. There would be riots.

Youre lucky at $100, my two nearest dealers charge $150