Misconceptions and oddities about our platform

[HARDTRAILZ]

Great tread

What tread are you referencing? You get new tires?

 

[Fire06]

Just learning to type ment to say " read "

 

[Mounce]

This one's for Envoy owners

"My Envoy's fog lights point down on the road so close in front of the vehicle that they're almost useless, I've almost quit using them altogether because they just aren't effective."
Your fog lights ARE adjustable, just like your headlights. Near the wires where the bulb plugs in at the back of the fog light assembly behind the bumper, there is a small adjustment screw that sticks down. It takes a torx socket to turn it, I believe the same size as the easily accessible headlight one up top. Loosening this screw (counter-clockwise) will raise the light upward and make it shine further down the road. Tightening this screw (clockwise) will lower the light and make it shine closer to the ground directly in front of your bumper. Use small adjustment increments, a little bit of a turn equals a lot of light beam movement.

my trailblazer's fogs are also pointing at the ground. Already found the adjustment but didn't know what to use to turn it, thanks!

 

[sunliner]

If you're replacing the thermostat you should replace the coolant temperature sensor right next to it.

Agreed....however around 06, they moved it to the passenger side, extreme rear. Just posting so other people don't drive themselves crazy looking for it like I did.

 

[Fire06]

I had trouble finding my sensor on my 06. Then it is a real bitch to change.

 

[chucki]

great thread.

 

[Bow_Tied]

This thread is very helpful to new owners!! Many thanks, folks.

 

[rocketsound]

While you're changing your thermostat is a great time to install a block heater, if you live in a colder climate. It's located just above the thermostat and to the rear, next to the coolant temp sensor. The large plug with 17mm allen recess in it unscrews from the block and you just thread in the heater. much easier to do when the alternator is out of the way! Sorry I failed to get pictures of it at the time, I'll update with pics next chance I get.
Katz 11484 is what I used on mine. Got it from NAPA
Might want to remove the thermostatic controller from the cord, it doesn't switch on the heater until -18 F!

 

[Mark20]

Considering the Silverado sits out all year the Kats may be a good idea for it. From their catalog it appears the 11484 will also fit the 5.3L.

 

[rocketsound]

It does, I put one in my Suburban. All the 5.3l, 6.0l and I believe the 8.1l have the large plug that unscrews to allow you to install the block heater.
On the 5.3l & 6.0l the plug is above the oil filter in the left (driver's side) rear of the block. Requires a 17mm allen bit to remove the factory plug. Here's a pic of the v8 so you get an idea what the plug looks like. Same plug on the 4.2l just near thermostat on driver's side of engine.

 

[Mark20]

Do you have to drain the coolant or can you swap it out fast enough to minimize its loss?

 

[rocketsound]

On the v8, the plug in the block is just about the lowest point in the system, so you're going to get wet or lose all your coolant. Unless you place a drain pan under it first. I had a 2005 Silverado up on the lift this morning, and noticed that it did not have the block drain plug that we've been discussing. It was a "B" code engine with an aluminum block. It's possible that only the motors with iron blocks have the plug. I will pay closer attention and see if that's true.

 

[Kazz]

Question on the oil pressure gauge. If it is a switch, why does my gauge fluctuate like a normal gauge? If the sending unit is a switch, wouldn't it stay at 40 or nothing versus fluctuating?

 

[Mounce]

Question on the oil pressure gauge. If it is a switch, why does my gauge fluctuate like a normal gauge? If the sending unit is a switch, wouldn't it stay at 40 or nothing versus fluctuating?

I believe it's the PCM fabricating fluctuations to fool people. Mine does the same thing.

4.2 = fake readings
5.3 = real readings

 

[The_Roadie]

That's right. It was presumably cheaper for GM management to omit the analog sensor and tell the the PCM coders to calculate fake values for the gauge to take into account RPM and perhaps temperature changes into the fake data.

It is evidence of total intellectual dishonesty motivated by the management culture of saving a dime no matter how much bad karma you're generating. As an engineer, I have very little respect for designers who obey such orders. My management may be frugal, but they know better than to ask me to lie to the customer like this.

 

[No Tyme]

Earlier in the thread radio back lighting was discussed. I presume it is the same for dash lights... solder required to replace and install...
How hard of a job is it? Has anyone done this?

Also anyone use these cargo shade covers? I don't want to add something that is going to rattle or make noise, but the idea of privacy is nice.

 

[Mounce]

For the lights check out the led mod thread starting at the beginning.

 

[Mooseman]

I use the cargo cover occasionally. Kinda neat and it doesn't rattle. It does get in the way when you need to transport larger items. It comes out easily but you're then you're stuck with it taking up some space.

I was lucky when I found mine in the local pick-a-part and cost me just $10.

 

[No Tyme]

I use the cargo cover occasionally. Kinda neat and it doesn't rattle. It does get in the way when you need to transport larger items. It comes out easily but you're then you're stuck with it taking up some space.

[SIZE=11.9999990463257px]I was lucky when I found mine in the local pick-a-part and cost me just $10.[/SIZE]

WOW, you got a deal. I am having second thoughts because I can't find one under $100. LOL... Good to know if I do decide to pick up one they don't rattle. Don't like anything that makes annoying noise in cars.
I do have a full size pickup for the larger items... My Trailblazer is a go to work vehicle.

 

[djthumper]

I use the cargo cover occasionally. Kinda neat and it doesn't rattle. It does get in the way when you need to transport larger items. It comes out easily but you're then you're stuck with it taking up some space.

I was lucky when I found mine in the local pick-a-part and cost me just $10.

I got mine for $20 and it was in pristine condition.

 

[HARDTRAILZ]

I use my shade all the time to keep stuff in back hidden. Love it.

 

[SnowBlazer]

I've always wanted a shade. No luck though

Roadie was going to sell me his but I haven't seen him on in the longest time. Hope all is well over there.

 

[littleblazer]

I've always wanted a shade. No luck though

Roadie was going to sell me his but I haven't seen him on in the longest time. Hope all is well over there.

I see him on on the Facebook page quite a bit.

One thing I never quite understood was why is there a fuse panel thing on the drivers side dash, like the full size. But it's not actually there. I think....

 

[24v 4.2]

It's on both sides. Helpful for accessing wiring behind the dash.

 

[northcreek]

I've always wanted a shade. No luck though

Roadie was going to sell me his but I haven't seen him on in the longest time. Hope all is well over there.

I have a grey one from my Denali...make me an offer ...Mike

 

[No Tyme]

Just my luck. I picked up a shade from eBay and it is a bit darker than I wanted... More of a camel color and my interior is shale... I guess brown against tan isn't too bad.

 

[l008com]

There is only a switch detecting oil pressure, so it's either off (0PSI) or on (reads 40PSI, but can be 12+)

All the more reason oil pressure should just be a light on the upper dash, and it's gauge space should be a transmission temperature gauge.

Also, you said "on the i6". Does that mean on the 5.3's the oil pressure gauge is "real"?

 

[Mooseman]

Yes, 5.3 oil pressure gauge is real.

 

[Paul Bell]

I see him on on the Facebook page quite a bit.

One thing I never quite understood was why is there a fuse panel thing on the drivers side dash, like the full size. But it's not actually there. I think....

If you wanted to remove the dashboard from the truck you'll see that these are bolt access covers.

 

[iraqvet13f]

"I went to change my spark plugs; when I removed the coil pack for cylinder 4/5, I looked in before starting and noticed there was a little bit of water in the bottom/a little rust on the bottom of the plug! Is something broken, did I blow a gasket or something?"
This is actually a known problem. Notice that there's no weatherstripping (rubber seal) on the back of the engine compartment, either on the hood or the body metal. What happens is sometimes in the rain or when running your wipers, some water trickles down onto the block and may get past the coil pack "seal." I use the term loosely because there's only one bolt toward an extremity holding the pack down, so it's much more difficult to get a proper seal around the entire perimeter. If there's some water present, soak out what you can, and let the rest evaporate until dry before removing the plug. When reinstalling your coil packs, you could ensure the area where the seal touches, and the seal itself, are completely clean. Making sure the bolt is properly torqued can aid in sealing. The gasket that is by the inside of the spark plug wells is actually used to retain oil; if you find oil in the spark plug well, THEN you have a bad gasket.

"I have a light that came on, I looked it up and it's the Reduced Engine Power light. How does it know I'm not getting full power, and what did I break?"
Luckily, this isn't just any issue causing the REP light. The REP light comes on when the expected position of the throttle plate and the actual position of the plate do not agree. Imagine this: you're accelerating briskly, and then you let off the gas pedal when you reach the speed you want. Suddenly the REP light comes on. Did you blow something? Is a valve stuck from your little bit of fun or something that is making you lose power? Luckily, it's not (relatively speaking) that severe! What likely happened is that you let off the accelerator, which tells the PCM to close the throttle, and then the throttle didn't go to where it was supposed to. This system is designed to give you a "limp" mode to at least be able to safely pull over or get to a shop/home if you're not far away, and it compromises by not allowing the throttle to open very far. This ensures that you are much less likely to have a runaway vehicle like we all remember Toyota doing a massive recall for. And yes, your GMT360 is drive-by-wire.

"I went to change my spark plugs; when I removed the coil pack for cylinder 4/5, I looked in before starting and noticed there was a little bit of water in the bottom/a little rust on the bottom of the plug! Is something broken, did I blow a gasket or something?"
This is actually a known problem. Notice that there's no weatherstripping (rubber seal) on the back of the engine compartment, either on the hood or the body metal. What happens is sometimes in the rain or when running your wipers, some water trickles down onto the block and may get past the coil pack "seal." I use the term loosely because there's only one bolt toward an extremity holding the pack down, so it's much more difficult to get a proper seal around the entire perimeter. If there's some water present, soak out what you can, and let the rest evaporate until dry before removing the plug. When reinstalling your coil packs, you could ensure the area where the seal touches, and the seal itself, are completely clean. Making sure the bolt is properly torqued can aid in sealing. The gasket that is by the inside of the spark plug wells is actually used to retain oil; if you find oil in the spark plug well, THEN you have a bad gasket.

"I have a light that came on, I looked it up and it's the Reduced Engine Power light. How does it know I'm not getting full power, and what did I break?"
Luckily, this isn't just any issue causing the REP light. The REP light comes on when the expected position of the throttle plate and the actual position of the plate do not agree. Imagine this: you're accelerating briskly, and then you let off the gas pedal when you reach the speed you want. Suddenly the REP light comes on. Did you blow something? Is a valve stuck from your little bit of fun or something that is making you lose power? Luckily, it's not (relatively speaking) that severe! What likely happened is that you let off the accelerator, which tells the PCM to close the throttle, and then the throttle didn't go to where it was supposed to. This system is designed to give you a "limp" mode to at least be able to safely pull over or get to a shop/home if you're not far away, and it compromises by not allowing the throttle to open very far. This ensures that you are much less likely to have a runaway vehicle like we all remember Toyota doing a massive recall for. And yes, your GMT360 is drive-by-wire.

Ok, So if the REP light comes on, what can I do to fix this? Repair / clean the throttle body?

 

[Mooseman]

You'd have to use a code reader and get the accompanying code to pinpoint the issue.

 

[02trailblazin]

Very nice write-up. I have comments on two items;

When the 4WD select switch lights continue to blink and don't go to steady on, that usually means that the TCCM did not get the correct feedback from the actuators and the commanded task was not fully completed.

As far as the alternator controlling its output voltage, that is something that the PCM actually takes are of. Don't know specifically what conditions this happens under, but cold temperatures is definitely one of them.

Could be due to something in the valve train or transfer case thatz been built from plastic by gm and needs to be replaced with aluminum thats why gm 4l60e-80e are because of the plastic pistons and other parts and the clutch bands no having the right amount of pressure becUse the solenoids are engaging due to the fault so it sends it ro the tcm which relays back to ecm and bcm into the pcm check and see if the physical aspects internally are the root to ur problems im in the middle of waiting for a 1600 reman transmission myself at this very moment so i can put her back together so my wife and kid can ride safely instead of having no 2nd gear and wont shift out of first. Unless ovee 30 mph so yea ive been researching alot the last week ita been on all 4 jack standa out back

 

[l008com]

That was..... hard to read.

 

[movietvet]

Sorry, late to this thread.

Ok, I just saw a video from a guy that calls himself, "The Car Doctor" and he had a 2002 TB and was covering the common problems with these rigs. The last one was strange and kind of crazy:

1. Codes related to VVT solenoid or screen problem. P0014, P0017 or P1345 at rf of head. Caused by low or bad oil or engine problems as bad as excessive crankshaft end play. If solenoid is replaced, the screen should be too and need to do a crank variation relearn to synch with cam.

2. P0440 for evap leaks. Common on the bigger rigs too, like my 05 Tahoe Z71.

3. P0340 for cam sensor problems and again do a relearn.

4. Service 4x4 system with code C0550 which usually means a failed transfer case control module and if replace, have to do a reprogram and relearn.

5. P0300 for CEL on or flashing, Ignition coils causing this on a regular basis or at least by 100k miles and do boots at same time, well duh...

6. Failing injectors from using poor quality gas. Hell, that can happen with any vehicle and we talk about it all the time at the Tahoe/Yukon forum.

7. Leaking water pump....CHECK, already done.

8. Failing fan clutch....CHECK already been done before I bought the rig.

9. Coolant temp low and is related to failing thermostat....CHECK, I did that along with water pump already.

10. Service air bag light on. Related codes B0026, B0024, B0043 and B0044. Can diagnose quickly by getting a 2 ohm resistor and unplug the connector at bottom of the steering column. Plug the resistor in at the module side of the connector. Turn key on and if light is now out, is likely a clock spring, this statement he said first. Then he said this: "If turn back on to double check and light is off, is likely the module and if continues to flash is likely the clock spring or inflator coil" which seems to contradict what he first said.

11. Now the strange one: Front diff problem with service 4x4 light on and clunk in 4x4 or is inoperative. Likely a differential actuator assembly at passenger side of oil pan and actually passes thru the oil pan. This part is supposedly no longer made and cannot get a new one and would need to get a used one.


As the fiance of a lady that just bought one of these I am aware that an 02 could have problems but we have only 70k documented miles on it. She is fretting now, to say the least.

Has anyone here ran in to any of the odd ones and are these typical as he said in the video? I numbered so responses could be tracked easier. Later all.....

 

[TJBaker57]

#1 & #3: I see no reason for a CKP relearn. Service literature does NOT call for a CKP relearn when servicing/replacing CMP components as no part of the rotating mass are affected.

#4: I have once or twice seen a C0550 and have never had to replace my original 2001 TCCM. I suspect a C0550 can be set by some momentary electrical gremlin at powerup or the like and I am loathe to replace a component for a situation that may never occur again. Plus I do not believe a relearn for the TCCM even exists.

#8: I would be willing to wager that as high as 90% of fan clutch replacements change out a fan clutch that is working as designed and most times the owner has no idea how it is supposed to operate to begin with. Now "working as designed" surely leaves room for improvement.


#11: To start with I would say there is already enough confusion in the online crowd about what is a differential, a transfer case or an axle disconnect so to use the term "differential actuator" doesn't help. I tend to be a bit OCD about terminology. To me the front differential on these trucks is on the left side of the oil pan and there is no actuator for it. My service literature identifies the part we commonly call a splined disconnect, or a front axle disconnect or similar names as the "intermediate shaft bearing assembly".



Whatever you call it while it is no longer available from GM there are several manufacturers still selling the part. Better yet, find a serviceable original and rebuild it yourself.

 

[movietvet]

I knew some of this is just the video guy's opinion but I had to ask. I will worry about it when and if it happens. It would just mean no 4x4. Not that important around here. Thanks @TJBaker57

The thing that threw me was the part about the oil pan being part of it all.

 

[TJBaker57]

will worry about it when and if it happens. It would just mean no 4x4. Not that important around here.

A thing to know is this: even in 2 wheel drive that front differential and that splined axle disconnect is still spinning pretty fast.

All related gears and bearings still require lubrication.

The front differential tends to get ignored and can fail if fluid changes are omitted, particularly if there are leaks and the fluid level gets low.

The splined front axle disconnect is typically poorly lubricated when new and is also ignored until it is far too late and may even be not repairable/rebuildable by the time the noises are noticed. If one has the facilities and abilities it may be wise to service that assembly before it is too late. I grabbed another unit at the Upull for rebuilding and upgrading and I will swap it out and then rebuild the one that is currently in mine for a future swapout.

A further benefit of grabbing one at a Upull is you can learn the ropes of getting one out of the vehicle without risking breaking your own unit!!

 

[Mooseman]

1. Codes related to VVT solenoid or screen problem. P0014, P0017 or P1345 at rf of head. Caused by low or bad oil or engine problems as bad as excessive crankshaft end play. If solenoid is replaced, the screen should be too and need to do a crank variation relearn to synch with cam.

The screens comes with the CPAS and have also been improved with the addition of retention wires on them. No relearn required.

3. P0340 for cam sensor problems and again do a relearn.

No relearn required

4. Service 4x4 system with code C0550 which usually means a failed transfer case control module and if replace, have to do a reprogram and relearn.

Only 02-03 affected by defective original TCCMs. No reprogram required if you get a used one. New or rebuilt needs a reprogram.

6. Failing injectors from using poor quality gas. Hell, that can happen with any vehicle and we talk about it all the time at the Tahoe/Yukon forum.

Very few injector failures have been seen here.

10. Service air bag light on. Related codes B0026, B0024, B0043 and B0044. Can diagnose quickly by getting a 2 ohm resistor and unplug the connector at bottom of the steering column. Plug the resistor in at the module side of the connector. Turn key on and if light is now out, is likely a clock spring, this statement he said first. Then he said this: "If turn back on to double check and light is off, is likely the module and if continues to flash is likely the clock spring or inflator coil" which seems to contradict what he first said.

Same for these failures, very few seen here but it can happen.

11. Now the strange one: Front diff problem with service 4x4 light on and clunk in 4x4 or is inoperative. Likely a differential actuator assembly at passenger side of oil pan and actually passes thru the oil pan. This part is supposedly no longer made and cannot get a new one and would need to get a used one.

They are available aftermarket, which a lot of them have improved the design of the shifter fork.

I think I know the video you're talking about. He's just a negative old coot and I have blocked him on YT just to avoid seeing his ugly mug. Just maintain it and enjoy.

And speaking of maintenance, as @TJBaker57 said, be sure to keep up with fluid maintenance, especially the transfer case, as it has a relatively short 50k miles service requirement. It uses Auto Trak II fluid.

 

[movietvet]

End of this week or next week all the fluids will be addressed. I have all the correct fluids, as per GM, and a new GM trans filter kit. I am curious about what @TJBaker57 said about lubing the front axle disconnect. Besides fluid changes, is there a separate lube procedure for it. I could look it up but I figure is better to hear it from someone who has done it.

Also, I already knew that the front diff still spins in 2wd but was unsure about the disconnect spinning. When I was in the shops, I did not see these rigs come in and had to deal with them. All info is good to know and it looks like at the 70k miles mark on our rig, I have already done the known water pump, fan clutch and water outlet weak spots.

 

[TJBaker57]

curious about what @TJBaker57 said about lubing the front axle disconnect.

Front Axle 4WD Disconnect Rebuild | offroadTB.com

offroadtb.com

Plus I have read here and there where folks have sourced a slightly wider bearing for the most common failed outer bearing and another owner who added a zerk fitting to allow the addition of grease? Not sure if that last one helps or not I am considering adding such near that outer bearing that most often fails first.