load'em

05 Suburban 4×4 Z71 115k. I have started noticing a small surge in the throttle when cruise control is engage and coasting downhill. It is as if the computer wants to accelerate but then let's off. The cycle is about every 2 seconds.

Has anyone else experienced this? Normal, or an indicator of needed maintenance?

in2pro

Here is what I found in the manual...
if you have no codes stored its normal ?



Service Information 2005 Chevrolet Tahoe - 2WD | Avalanche, Escalade, Suburban, Tahoe, Yukon (VIN C/K) Service Manual | Document ID: 1801399
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#PIT3073A: Downhill Cruise Control Surge - keywords buck chuggle decelerate driveability flare gas L18 L33 L59 LM7 LQ4 LQ9 LR4 performance - (Mar 28, 2006)


Subject: Downhill Cruise Control Surge


Models: 2002-2006 Cadillac Escalade Models

2000-2006 Chevrolet Silverado, Suburban, Tahoe

2002-2006 Chevrolet Avalanche

2000-2006 GMC Sierra, Yukon Models




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The following diagnosis might be helpful if the vehicle exhibits the symptom(s) described in this PI.

Condition/Concern:
Surge, chuggle or buck while driving downhill (Hilly or Mountainous Terrain) at highway speeds with the cruise control set.

Recommendation/Instructions:
If there are no DTCs stored and this does not happen with the cruise control in the off position, no repair attempts should be made as this is a normal characteristic of the vehicle.

Important: If comparing to a like vehicle make sure the vehicle is exactly the same year, make, model, engine, transmission, axle ratio, tire size, as the owners and that the vehicle is driven at the same MPH the surge occurs and same hill/mountain.

Note: The dealer should also review the "using cruise control on hills" section of the Owner's manual. This section states the following about using the cruise control while driving downhill: (When going downhill, you may have to brake or shift to a lower gear to keep your speed down. Of course, applying the brake takes you out of cruise control. Many drivers find this to be too much trouble and don't use cruise control on steep hills.)

Please follow this diagnostic or repair process thoroughly and complete each step. If the condition exhibited is resolved without completing every step, the remaining steps do not need to be performed.



GM bulletins are intended for use by professional technicians, NOT a ""do-it-yourselfer"". They are written to inform these technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the information.
WE SUPPORT VOLUNTARY TECHNICIAN CERTIFICATION

load'em

Thanks for hunting that down, it explains exactly what I'm experiencing. Hard to believe its normal. Oh well. Had a service tech at the dealership try to tell me yesterday it was a dirty throttle body. Probably would have believed him if I hadn't just cleaned it before our trip.

On a side note, I was there asking if they were seeing many vehicles come in with the rear defroster broken off and how they are fixing it. I have tried the defrost glue and it fell off again a week later...Apparently they have been trying to solder them, but cannot get the solder to hold to the glass so the are just replacing the whole back window. For a $1000, I'll figure something else out. Think I make give this a try first: http://www.mgchemicals.com/products/adhesives/electrically-conductive/silver-conductive-epoxy-8331/

73shark

After you get it re-glued, stretch the coiled leads so when the glass is shut they're not under tension. That'll reduce the stress that tends to pull them off.

load'em

Awesome, will do! Thanks

in2pro

I have not had to repair mine, so my advise is anecdotal, the key will be to controlling the heat to solder it, use a hair dryer to warm up the entire area around the solder connection and use the biggest tip you can find, prep the area and have a second set of gloved hands to assist so that heating time to the area is minimized...

load'em

Sounds like good advice and I was going to try but a grand for a new window is a costly mistake. Guess I'm a little more risk averse than I thought. If the $40 glue don't work I may buck up and go for it.