Chevy Trailblazer 4x4 Not Working? Four-Wheel-Drive Actuator Problem Symptoms
Actuators and Encoders and Solenoids, Oh My!
It all started with a 4-wheel drive switch. My husband was driving our 2005 Chevy Trailblazer, and when he went to change the switch into 4 wheel drive, the switch wouldn't budge. Instead, it broke off--through no fault of my husband I'm told--and thus began our massive 2013 hunt for what's-wrong-with-the-Chevy-4WD (not to be confused with the-Chevy's-brakes-are-still-squeaking-after-we-changed-pads-and-rotors 2012 fiasco). I decided to write this article because I've learned far more than I ever wanted to know about Chevy vehicles in Chevy forums from so many others who have written about their own Chevy issues. Perhaps this hub will help other folks with the same symptoms jump straight to the source of the problem instead of taking the long route. And yes, there really is a Trailblazer forum you can join at trailvoy.com.
AC Delco Actuator with Encoder Motor
Symptoms of Encoder Motor Failure
Other vehicles may be different, but on our Trailblazer the symptoms were that the "service 4WD" light was on, lights on the switch would blink and then remain steady, but the truck wouldn't shift into four wheel drive. No noises could be heard underneath, as if it wasn't even trying to transfer. We thought it was a switch issue (and it was the cheapest fix), so we bought a $28 4-wheel drive dashboard switch from the stealership and popped it in. We still had issues. We read on several forums that the #8 fuse in the front and #45 under the rear driver's side seat often need to be pulled for a minute to reset the transfer case module. So we tried this, but it still had issues.
Give DIY a try?
Our eBay Actuator
At this point, we were saddened to realize that we might actually have to shell out substantial money to fix this problem. Upon further research, we found that many folks were finding success in replacing the front actuator. Here is where it becomes confusing! We found one on eBay and patted ourselves on the back for only having to pay around $100 to fix this potentially pricey problem. NO. After that didn't work (thank goodness for "returns accepted" policies on eBay), we took it to a shop. They read it with their nifty high-tech Chevy scanner tool and claimed it was indeed an "actuator" problem. Upon even further research, we found that the words "actuator" and "encoder" were used interchangeably on many websites. We once again patted ourselves on the back and bought a $150 Dorman encoder motor on Rock Auto.
NO! Not only did it not work, but the rig didn't even recognize it at all--none of the switch's lights would light up.
Finally, the Answer
Luckily, my dad has a buddy who owed him a favor. After taking a look, he said he had seen aftermarket encoder motors fail to work, and that an AC Delco actuator might do the trick. Come to think of it, I did see that written in a forum somewhere once upon a time, but failed to find enough suppporting evidence to back that up. We bought our final part for $200 out-of-pocket, made sure it said "AC Delco," and collectively held our breath as we popped it in. Sure enough, it did the trick. No more service light, no more non-moving switch mode light, and we can hear the rig shifting when we turn the switch. Now if we can only figure out why the driver's side headlight keeps burning out every few months...