iamrich

I would suggest buying a code reader, some are very cheap. When you get the message plug it in and read the error code. It may not solve the problem, but it will narrow down where the problem may be.

4x4van

My money is still on the encoder motor. I know that it is new, but it is NOT an OEM encoder motor; that's the point. I did what you are doing; searched the internet for troubleshooting and repair ideas. I even went to the Chevy dealer initially and had them diagnose it. Their answer? Encoder Motor. They wanted $760 to fix it ($420 for the part, $340 for labor). That's when I put the Dorman part in myself. Saved nearly $500, whoohoo! Wrong. 1 1/2 years later, I replaced it (lifetime warranty) again. Wrong. 6 months later replaced the dash switch. Wrong. Continued to have intermittent 4WD issues which culminated in the "neutral" problems outlined above. Finally replaced the Encoder with OEM. Solved ALL of the various 4wd problems that I had been chasing for years.

My point is this; the encoder motor doesn't just physically shift the transfer case. It also has multiple contacts inside that tell the computer what position it's in. And when that starts to glitch, the computer reacts in weird ways, and does things that don't always make sense. Here are just some of the issues that I had, sometimes by themselves, sometimes in combination, but all eventually solved with the OEM encoder motor:

-Service 4WD warning on dash, 4WD switch non-responsive
-4WD switch lights off, non-responsive
-4WD switch lights on, but non-responsive
-Truck shifts itself into 4LO and will not come out.
-Transfer case shifts into nuetral while traveling at 70mph; shifting transmission into park rests transfer case.
-Transfer case shifts into nuetral while traveling at 70mph, shifting transmission into park DOES NOT reset transfer case, but pushing Auto 4WD button does reset it.
-Turning off and re-starting truck solves issue(s)
-Turning off and re-starting truck DOESN"T solve issue(s)

BTW, sometimes the "Service 4WD" warning would show up, other times it didn't, particularly with the neutral issue. And during this entire time (several years), I never took the truck off-road because I was never confident that I would have 4wd when and if I needed it.

The fact that ONLY your 4LO is not working right now, and that sometimes by reseting the computer it works for awhile, and that you have a Dorman encoder motor... those 3 things add up to what I believe is the clear answer; I've been through the same things and I'm telling you it's the Dorman part. Don't get me wrong, I'm in my 50s and will always save a few bucks using aftermarket parts when possible, and I've always had good luck with Dorman parts. But the encoder motor is one of those few exceptions; it MUST be OEM or you will never chase down your 4WD problems. The money that I saved initially with the Dorman encoder was NOT worth 2+years of ongoing headaches and no reliable 4WD. In the end, I STILL bought the $420 OEM part, in addition to the $285 Dorman part, the $100 dash switch, and even a $1500 transmission, none of which were actually needed!

Just my nickel, your value may vary.

Ian Anderson

Well, I do appreciate the advise for sure,.. Most would argue with you and say, Your wrong !...But I have no other clue here,... LIKE YOU !, I replaced the Switch !..It worked for a while there,
..........then the same problem came back,.......Then got under the truck and worked the Cross Member out as well as the driveline and replaced the switch motor and "I KNOW" ! its in there right
...as well as ran voltage meter tests to make sure I have them all hooked up right,.. PUT ALL THAT BACK IN.. and now I'm back to where started.....So !...if Its not something in the computer its self
that I can make right here to match this part!.... IT HAS TO BE that darn None OEM Switch Motor its self....so what are we saying here ?.. This switch motor .. WILL NOT match GM's computer and
there is some design that GM has to make sure "IT HAS TO BE" One of their parts to work ?..............seems like they new that would happen..
..................HERE IS THE MOTOR I USED !!!.... seems to me that, its just an Encoder Ring and a Servo Motor there,..so the Encoder Ring.... and the Computer.... WILL NOT talk to each other right ?...
the servo motor its self is just a Stupid Motor and knows nothing more then to Run with voltage,.. the hole thing seems stupid to me that IT HAD TO BE a GM part to work as well.. Like I said,........
.....heads will roll on this one if this is the case.... Back to work on this I guess,...lol lol....




....So ... It back under the rig and Pull that part back out !.. and Put in a OEM part I guess,.. Maybe I can get a refund for this part,.. Did read where someone else had this problem and THEY WOULD NOT
refund the price of the motor for him,.. NOT SURE WHY ! other then, they have had that happen "MANY MANY TIMES".......I will get to the bottom of all this as there is No other chose here....so ITS ON GOING at this stage,...once gain...Thanks for the assistance here on your experience.... what ever anyone does,.. DONT BUY One of these parts from these folks,........ their no doubt setting back with a big grin on their faces Counting the Money !, as well as I WILL keep posting what I have found out,.. THERE WILL BE HEADS TO ROLL on this one if this motor WILL NEVER WORK with GM's computer on the truck....I WILL get my money back and there will be answers here by the seller .........and even GM their self's in the matter...... I COULD !.. replace the Encoder Ring its self and place it back in the (Dorman) hosing its self !..... and see if that would work.. the RING is cheaper then the hole part.....but after seeing how hard it is to Re-Clock the set up !..........................I'm hesitant is all....



I appreciate your help as well as your suggestion,.. but more then likely ...This will get me no where as, it will more then likely show the Encoder "RING" in the Motor as the error !..so to buy the test equipment....
ON TOP OF the new OEM Encoder Motor seems like cutting my other hand off as well is all..lol lol.... would be nice to have but... The problems seem clear now.. Thanks for your help as well bud !..






Ian

BabeBluHoe

Here is what I am coming up with: Tahoe will go in to 4H when I hit the button, after so far down the road (maybe about 30mph too) I get my service 4x4 light on. I can't get it out of 4H.
So hooked it up to the computer and it reads a propeller shaft sensor is bad.
It also under load does NOT stay is 4H. I got stuck in snow up over my bumper last winter. My road doesn't get plowed much.

any one else have that code?

Thanks!

auburnspitfire

2013 Tahoe with Service 4 wheel dirive light that came on and went off. Vehicle will not shift into 4 wheel drive high, only stuck in AUTO. What causes this? Dealer can't check until next week.