Allison 1000 Shift Solenoid Kit 7-Piece 5-Speed Duramax

This is the complete seven-piece shift solenoid set for the Allison 1000 and 2000 series five-speed (LCT1000) automatic used behind the 6.6L Duramax and the 8.1L gas big block. It covers everything that bolts to the control valve body inside the pan: the shift solenoids, the PWM torque converter clutch solenoid and the main modulation (line pressure) solenoid. It replaces OE numbers 8683167, D116420A, 29533074, 29533075 and 29536833.

Fitment is the 1999-2005 five-speed Allison. On the light-duty side that is the 2001-2005 Chevrolet Silverado and GMC Sierra 2500HD/3500 with the LB7 and LLY Duramax or the 8.1L, plus Suburban 2500 and the Kodiak/TopKick C4500 and C5500 medium duty trucks. This is the five-speed kit only. The 2006-and-up six-speed Allison uses a different solenoid set and a different internal harness, so verify you are on the five-speed before ordering.

The symptoms that put this kit on the counter are a truck that hangs the 1-2 or 2-3 shift, bangs into gear, drops into limp and defaults to a single gear, or sets solenoid circuit codes such as P0751, P0752, P0973 and P0974. A TCC solenoid that has gone lazy shows up as converter shudder at light throttle or no lockup at all, which cooks fluid temperature on a loaded truck. Because the solenoids sit under the pan, the labor is in the teardown, not the part, so techs replace the whole set at once rather than chasing one at a time.

Bench work is straightforward. Drop the pan and pull the internal filter, unplug and unclip each solenoid from the internal harness, unbolt the retaining brackets and lift the solenoids off the valve body. Lube the new O-rings with clean fluid before seating them so nothing rolls or pinches, torque the retainers to the factory spec, then reconnect the harness and verify each connector is fully latched. Install a new pan gasket and filter, refill with Allison-approved TES 295/TES 668 fluid, and clear codes before the road test. A relearn drive cycle is normal after the swap.