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Last week, PickupTrucks.com held one of its periodic load lugger shootouts where it brings together the heavy haulers from General Motors, Ford and Chrysler to see which pickup truck is the top dog. After running acceleration tests at Milan dragway, editor Mike Levine and the crew moved the fleet of nine trucks to the GM Proving Ground in Milford, MI. During towing evaluations on the 7.2 percent hill, Levine discovered an issue on the Chevy Silverado 2500 while the gas-engined 3/4 ton truck was towing 10,000 pound trailers up the hill.

The GM trucks incorporate a hill-hold feature into the stability control system. Hill-hold is supposed to detect when the vehicle is on an incline with the brakes applied. When the driver releases the brake pedal, the valves in the stability control unit retain the pressure in the brake lines for up to 1.5 seconds. Once the timer expires or the driver applies the accelerator, the valves release the brake pressure.

During testing, Levine discovered that the system was not holding the pressure on the 7.2 percent hill for any of the GM trucks and notified the engineers on hand. Oddly, a later test found that the system was working properly on the steeper 16 percent grade. GM engineers investigated the issue with engineers from system supplier TRW and found an incorrect calibration value in the control software for the accelerometer used to detect inclines. This prevented the system from correctly detecting the smaller hill.

The code was corrected and updated software began rolling out to the production line this past Monday, July 19. The same software update is also going out to dealers so that trucks in stock on lots and in for service can also be updated. GM is still considering whether to issue a recall or a technical service bulletin for trucks that have already been delivered to customers.

[Source: PickupTrucks.com, TRW]


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  • 15 Comments
      • 5 Years Ago
      Imagine if Toyota had an issue like this, it would be all over the news.

      Not surprised that GM's lack of R&D missed this. After all anytime the government gets their hands on anything it goes to poop. I wonder how many other problems (known and unknown to GM) these vehicles have.
      • 5 Years Ago

      I've yet to see one of these new Chevy's on the road...are they available yet? I've seen a bunch of the new Fords.
      • 5 Years Ago
      It is Ironic that the fault was first identified by an auto journalist on GM's own proving ground. Why didn't GM find this problem before it shipped?
      • 5 Years Ago
      Haha, hilarious.

      I was at Hudson Mills Metro Park for a round of disco hippie golf and the guys from PickupTrucks.com working on their reviews. It was pretty cool seeing the big Detroit iron parked out on the lawn.
      • 5 Years Ago
      Good Job Mike! Keep up the good work!
      • 5 Years Ago
      Who says the automotive press doesn't provide a valuable service? Kudos to PickupTrucks.com.
      • 5 Years Ago
      Why is this feature needed anyway?

      More stuff to go wrong, IMO.. -_-
        • 5 Years Ago
        I'm happy to use two feet when moving a trailer around. It's only really needed when you are on a steep incline, and I'm already used to shifting over to using two feet. All this software in cars is getting a bit scary.
      • 5 Years Ago
      this probably helps the 1% that actually use their truck.
      • 5 Years Ago
      I'd have thought this would be something that could have been rolled out via OnStar, though it could be that the system to be updated is too-far detached for that to be possible.
      • 5 Years Ago
      Why didn't GMC's vast engineering department catch this before the production of these vehicles had started? This smells like the problems that cropped up with the new Shamaro AFTER production had started - and that vehicle took a long time to come to market after the concepts were developed. This is the same company that wants you to buy Volt which really doesn't bode well. If GMC can't get a pony car and a truck right with the details, what joys of ownership await the idiots who buy a Volt (more complex than either truck or Shamaro)? This is the same company that sells a Malibu that can't seat adults in the back if adults of any height are driving - and the same company that allowed huge hoop trunk hinges to be used on the LaCrosse that consume HUGE quantities of trunk space. Think about it. It took a MAGAZINE TEST to produce what any qualified engineer would have caught if he had his eyes open!
        • 5 Years Ago
        Is this all you do? come to Autoblog and bash GM? seriously all your posts are "GOVERNMENT MOTORS GOVERNMENT MOTORS GMC GMC GMC". I don't know what you're trying to accomplish, but every post you make about GM is completely pointless. Mistakes happen (in fact this was not with GM, but their supplier). If they tried to sweep it under the rug, that would be another story. However they listened to the customer, found it, and promptly fixed it. What's so wrong about that?
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