gmc canyon / chevrolet colorado quick fix info
I'm not smart about cars because I want to be. I'm smart about cars because I have to be.
This is especially true if you drive a GM vehicle.
I know just about all there is to know when it comes to common issues with the GMC Canyon, a.k.a. Chevrolet Colorado, a.k.a. GMT355 pickup truck.
Driver's door popping sound when opening or closing
Tighten two nuts on very long bolts that are in open view on the inside front of the door. Can't miss 'em. Tighten by hand, because they're going to become loose again anyway.
Cruise control stops working
Brake light assembly recall (does affect cruise for whatever reason). Fixed at GMC dealership at no charge.
Hard shift from first to second gear in auto transmission
Fixed with PCM software upgrade at GMC dealership. Haven't done this yet. It's about $100 to have the work done even though it takes the dealership only five minutes to do it.
Slight booming sound at idle
Idle on these trucks is set too low, causing a slight booming noise. Also fixed with PCM software upgrade.
Gas gauge isn't as accurate as you'd like
Once again, fixed with the same PCM software upgrade.
Fan settings 1, 2 and 3 don't work, but 4 does
Blown blower resistor. This part, specifically, located under the passenger side footwell. Look for the white connector held in by two gold screws. Unscrew, pull out carefully and you'll see this big green thing attached to it.
The money you save by doing it yourself: About $275.
That's what you need to replace, IF the connector pins on the white part aren't fried, in which case you'll need the whole wiring harness kit (wire with connector + resistor).
To replace the harness, you have to take off the glove box and the right side panel which is seen when the passenger door is open. Glove box is held on by three screws in plain sight at the bottom. Take off the screws, open glove box slowly, push in either side so the plastic flaps clear, and pull straight out. After that, reach in and pop out the right side panel. You'll now have a clear view of the connector right in front of you. Since the harness is a complete kit there's no tools involved as it's all snap in/out connectors.
But even if you perform this fix, the problem will come back if you don't fix the ground, which leads me to...
All interior cabin fans shut off for absolutely no reason while switch is on
Oh boy, did this problem tick me off. You're driving along with the fans on, and then the fans die completely. Truck is still running fine and everything works - except the fans. Switch off, switch on.. nothing. All four fan speeds are dead. Then, by what seems like **magic**, the fans turn back on again.
The root cause of this problem is so unbelievably stupid that it just boggles the mind. And in addition, if you don't fix this yourself, your resistor (and most likely connector as well) will keep frying/blowing out unless you do this stuff.
Okay, here we go.
The problem is at the splice block. This is where a bunch of ground wires go. It is a small black box mounted on the passenger side fender. You'll see it in plain sight. Open the hood, look where your air filter is and just to the left of that mounted to the fender is the splice block. It is held in place by an attached metal strap with a 10mm bolt.
The block itself is not the problem. It's the way the bolt was installed.
With the truck off, pull off the air filter cover so you can get to the bolt with a ratchet. Then pull the bolt out and take the splice block along with it.
What's under that metal strap you just took off? Probably a small bit of corrosion, maybe a little gunk, and the biggest offender, paint.
What does this mean?
It means the strap was not technically touching bare metal. And that means you've got a crappy ground.
The fix? So easy it's not funny.
Take a Dremel or sandpaper and take off the paint where the strap connects to the fender. Then use a metal brush to clean the bolt (there's probably rust on it). Then sandpaper both sides of the strap where the bolt is until you see brass. Clean up, screw the bolt back in, seal it up proper so it doesn't rust on you (use RTV silicone for that), done.
What did you do here? You fixed a GM design flaw. You made the ground actually work like it's supposed to, and guess what? That stupid fan shutoff problem disappears - assuming your resistor and white connector under the footwell aren't burnt and in good shape. If not, pony up the $37 and have at it. Cheap fix for properly working fans as far as I'm concerned.
~ ~ ~
Whenever anybody calls GM vehicles junk, I never argue. For whatever boneheaded reason, I just like GM cars and trucks. Yes, stupid stuff on them breaks that simply doesn't happen on other cars. The only exception to the rule are most Buicks. Not all, but most. Buick is one of the few GM divisions that knows how to construct a car correctly. It's the reason I have an '89 LeSabre now.
Anyway, if you happen to own a GMT355, now you know the more common problems and their solutions.
The people I feel most sorry for are owners of GMT355's that are early 5-cylinder crew cab models. Most of those trucks are an absolute nightmare, such as the HVAC leaking water on the floor, the rear glass falling out of their tracks, and well.. let's just say the list is really frickin' long for annoyances with those trucks. 🙂