I have a 2001 Sierra 2500 HD w/ the 8100 big block & Allison trans. It does not have a throttle cable, it operates by a throttle control sensor, in case that's relevant to the problem I'm experiencing. This problem began about a month and a half ago (July '05) quite infrequently at first (approx once a month) but has now progressed to almost once daily. Also, it occurs only in the afternoon on hot days, never in the morning or on days that are cool, (cool by Arizona standards). Also, it seems to happen within 2-3 miles of my start point, and only at highway speeds; it hasn't occurred on surface streets yet. I will be driving along, then it feels like I suddenly took my foot off the accelerator, the BATTERY light comes on, and the tach drops to zero simultaneously. The first few times this happened, it lasted only 3-4 seconds, then resumed acceleration, the BATT light went off & tach read normal, all simultaneous again. Now when it happens, it doesn't resume itself. It cuts off, (the truck actually quits running) I have to shift to neutral (otherwise the trans slows me down very abruptly) and coast off the highway, steering hard because I lose the power steering. This scares me because if it starts up on it's own again like it was first doing, I will get power steering back and am afraid to be oversteering when it kicks back in. After I stop, I shift into park, turn off the ignition and turn it back on. The truck runs fine all the way home. (Approx 25 miles) I have brought the truck to a GMC dealer and they have scanned the ECM and BCM for any codes that might have stored, but there were no codes. Suppossedly no bulletins, recalls, etc...either. But unless it actualy acts up for the technician, they cannot diagnose the problem. Has anyone else had this problem, or have any suggestions? Please don't suggest battery, cable connections or corrosion, that's all been checked. Any OTHER suggestions that may help?? Please? -Kristine[/size][/size][/size][/size][/size]

is it cutting out at cruiseing speeds or durring acceleration? if during acceleration a common problem is the alternator over charges which send the computer system into a closed loop mode which is when the stall occurs.

It cuts out at cruising speed, not acceleration. It cuts out when cruise control is on or off, it doesn't seem to matter.

it has to be an electrical problem somewhere. the only thing to do would be find a lab scobe that you can keep pluged in for a day to record all of the data being processed.

I had a similar situation with a '96 Silverado. My issue only occured while using the cruise control. The module was replaced and I haven't had the issue since.
By the way, I'm looking at an '01 Sierra HD 2500 with the big block like you have and was curious about its performance (dependability) and gas mileage. I'm sure the mileage isn't far into the double digits, but the truck is really nice and I love the power.

Good Luck,