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tblazed: where have you been? Haven't heard from you in quite a while. I hope you had the dealer replace the brake light socket too. The bulb wire contact shows obvious signs of arching. That means the socket contacts are also burned and pitted. This can be a problem with wire insulation overheating at the point of connection to the socket, AND, the arching (sparking) can play havoc with the electronic systems. This is possibly a clue when looking for various glitches we've read about. Is the bulb a combo. brake and turn signal bulb?
Frank
Well, they must be making them better. My '02 was in a few times before 6500 miles.
To 2k_impala_ls - I had my 2003 TB in the shop for this 4WD problem at least 5 or 6 times - you might also notice that the 4WD is not operable when this happens. If you turn the ignition off and on, it clears itself until the next time it happens. They replaced my 4WD transfer control module twice but it did not fix the problem. On one occasion I was lucky enough to have it happen and I took it straight to the dealer who hooked it up to their diagnostic thing. The codes were not useful. They were puzzled to find there was no power to the rear grid. I think they replaced my ignition switch next. But the 4WD light kept coming on, and the 4WD would be inoperable until I turned the car off/on again to clear it.
Finally, this last time I brought it in they figured out what the problem is, because it hasn't happened in 7 months now (it was happening about every 2-3 months).
Here's what my service ticket says: Scan system for codes found C0550. Check for bulletins replace transfer case control module (this is my third now) and reprogram per bulletin# 02-04-21-0060
Hope this helps
a) had this problem, and
b) had their dealer fix it.
Of course, I took the assistant service manager along and could not duplicate the problem while he was riding along. On the way home, you guessed it...
*sigh*
Other than this, my wife has 2400 miles on her Envoy, which we've only had for five weeks. She loves it, except it also does an intermittent shudder at idle (tach jumps)...
--Robert
ADAPTIVE SHIFT CONTROL
The 4L60-E uses sophisticated electronics to modify shift patterns as conditions dictate. The Powertrain Control Module (PCM) monitors factors such as throttle position, vehicle speed, gear range, temperature and engine load. The PCM also measures changes in the operating condition of the vehicle, which occur naturally over time as components wear. Based on these measurements, shift timing and hydraulic line pressure are adapted to maintain optimum shift feel under different conditions - for example, during heavy hauling or trailering. This results in improved drivability and fuel economy. The PCM also allows the system to self-adjust for minor variations in each new unit, ensuring that every customer experiences consistent performance, and ensuring that the transmission will produce a constant high level of performance for the life of the car.
Also (may or may not be related) Again on interstate cruising, It feels as if the trans "hiccups". It is like maybe the torque converter is engaging/disengaging. Say you crest a very very slight incline and you let off the gas just a little you can feel it. I seem to notice this happening more and more now.
Any one felt either of these or had any corrective action for these symptoms???
Thanks so much!!!
Yeah, Borla is good but pricy. Maybe you could check with a custom exhaust shop and they could bend a system to fit your vehicle. Borla is all stainless and has a 1,000,000 mile warranty.
Be ready for more incabin noise with a non OEM exhaust.
- WPK
I used sound deadener to quiet my Borla. Put in about 160 sq ft in floor and doors. It was a big job but results were worth it. I live in SW Ohio, weather is not as bad as maybe in your area.
Thanks!
Go out in the mud and floor it. One roostertail: standard differential. Two roostertails: limited slip differential. This works best if you get someone you don't like to stand behind the car to watch. Also, this is when the On Star comes in handy, as you'll likely be calling a tow truck to get pulled out of the mud.
Please take pictures and post here. Thanks.
Was the reason you added the sound deadner for the Borla or were there other motivating factors. How much quieter did you find the Envoy?
How about the wind noise? Is that a problem on your vehicle? How much did it change your tire noise?
How about source you used for the deadner. 160 ft can get pretty pricey
thanks
Paul P
and, what are the benefits and downsides to having it?
thank you poles
Thanks!
Both real wheels get power on any differential most of the time. An open differential allows the wheels to turn at different rates to faciliate turning. The flaw is that if one wheel spins, it ends up getting all the power. That is not the intent! If you saw the innards of one you'd see quickly how this happens, but it can't explained without pictures.
With a limited slip, the wheels can turn at different rates up to a point. Then the cluthes engage holding and the axle is partially locked up. The wheels will turn at basically the same rate.
Anyway, no triplet has a limited slip.
The third type of differential is the locker. Too much slip = the axles lock together and the wheels turn at exactly the same rate. Different technology - same basic goal.
Also, there is a common misconception out there that if you have a limited slip or a locker, you've got twice the traction. That is false because as I stated, an open differential is truly 2 wheel drive. It's only if one wheel breaks loose that it goes to hell.
I would add that in some cases yes you do get almost twice the traction, for example on a wet street. With an open dif, it is easy to spin one wheel, the right rear, and go nowhere. With a limited slip, you will still spin the rt rear, but torque will transfer to the other side through the clutch pack in the dif, and if you spin the left wheel too, you will still have more forward drive traction from friction of two tires against the wet street. Happens easily with my S-10 that I put an Auburn Limited slip in back in '89.
The Eaton G80 locker used in the Triplets adds a centrifugal mechanism to only engage the clutch pack when one wheel spins faster than the other and forward movement less than 20 mph. And they don’t simply "lock together", the two axles are then coupled together through a clutch pack. Otherwise if you spun a wheel taking off from a stop making a turn, there would be no “give”, there is with the clutches.
This locker mechanism is desirable because No.1, the clutches are disengaged all the time unless wheel spin engages the mechanism. With a limited slip, the clutches are always engaged and work every time you go around a corner. That’s why you have to maintain a limited slip periodically, and why they do eventually wear out the clutches and get less effective. But a locking dif really doesn’t have a maintenance schedule except to check the oil level every 7500 mi .
Reason No.2, with a limited slip on a wet street, making a corner, it is very easy to break both wheels loose equally because one breaks loose, transfers power/torque to the other wheel through the always engaged clutch pack, and in an instant both tires are spinning and you’ve just done a 360° in the intersection! I speak from experience. Above 20 mph a locker will act just like an open dif and you can’t break both rear tires loose under power on a slick spot.
It refers to it as the "Eaton G80 locking rear differential." Eaton has to be considered the correct source.
Also, from GMC, the option has always been "locking rear differential."
Those RPO codes are different year to year. Do a query on GMC Envoy RPO G80.
I'm sure there are articles out there that refer to it as a limited slip differential. Some people simply use the terms incorrectly, thinking a limited slip and a locker are the same thing. To the non car nut, they basically are the same.
This link is a gateway for several model years.
http://gm-trucks.com/RPO_03_GMC.shtml
Also, calling amsoil today to see if their new gear oil is compatible. I am assuming since there are still clutches in there that you would still need fluid compatible with limited slip?
Thanks for all the great info!!!!!
As far as Amsoil, I did email them and they replied back their gear oil would work fine, then at the bottom of the response there was this disclaimer:
"Every attempt has been made to ensure that the information provided in this e-mail correspondence is accurate and reliable. However, AMSOIL Inc. makes no warranty, guaranty or promise (express or implied) concerning the
accuracy of our e-mail response as it is based solely on the information provided to us by the e-mail originator."
Also emailed Royal Purple. Their response was:
"Our Max Gear 75w90 meets and exceeds that GM spec.
Thanks
Patrick Burris
Technical Advisor
Royal Purple Ltd."
And no disclaimers. My dif now has two quarts of fresh Royal Purple 75W-90 in it. This oil is readily available in a lot of auto supply stores too, unlike Amsoil.
The "Genuine GM" gear oil is $20-30 a quart compared to less than $9 a qt for Royal Purple, and the RP already has the friction modifier additive for limited slip in it.
You might want to check your service manual. NO "limited slip" - only the Eaton locker is shown.
I did not notice a big performance gain from the Borla. I do like the visual gain.
If you go ahead with the Borla, make sure you keep your old system for a while to make sure you are satisfied with the Borla. That way you can reinstall the OEM and sell the Borla if it is not what you want. The GM OEM parts are expensive to replace when you have to buy them from GM.
Replacement Tire Question: My original equipment Michelin Cross Terrain tires should be replaced before another Northeast winter. The Michelin tires have been great, but are expensive. I was wondering if anyone has any experience/comments on Pirelli Scorpion STR A tires? The Pirellis are less expensive than the Michelins, but seem to have good write-ups.
A lot of the confusion sets in because regardless of the application, GM refers to it as "G80". On trucks that usually means a locking differential, on cars that means a limited slip or "Positraction" which is a GM name.
A follow-up to earlier posts of the surge-clunk with my 2002 Envoy SLT. In a nutshell, the same scenario that has been described in several posts by a number of us: start the car; drive a short distance; come to a stop; the car surges forward (ie, the 'have I just been hit' lurch).
After 3 trips to the dealer, the first 2 sending me off with the "unable to duplicate" response, I now have an open case with General Motors as there is no known fix for this problem. My dealership states that they have seen this in 1 other car and they think it has something to do with the air suspension and the rear drive axle {?}. So, I have a car with a problem and no cure.
I have been going round for round with GM customer service. Their "solution" is to offer me a 5 yr, 50,000k GMPP at n/c. It's worth noting that this additional coverage started from day 1, 0 miles...translating into 2 yrs, 24,000k.
After enduring the endless minutia that was my latest conversation with the 'customer service manager' (who, btw, was not empowered to negotiate nor 'allowed' to disclose his supervisor's name, I called it a day. But, I have not accepted this.
I'm interested to hear from others who may be in similar 'unsolvable' situations and what the majority would feel equitable. The bottom line for me seems that I have a broken (expensive)car, problem and any related damage unknown, and what I would consider a weak proposal for resolution.
Thanks so much for any feedback, guidance!
Mine has the air suspension, G80 and 4.10 rear axle ratio.
5/50 seems cheap to me. Now a 100,000 bumper to bumper would be nice, or that 100,000 mile GMPP at a really killer reduced price.
Let us know how you make out.
They sent us a letter upping our trasmission warranty to 100,000 and they consider the case closed.
BBB arbitration was a waste of time.
Keep us posted if you find a solution.