Replaces all seven shift, PWM and main modulation solenoids on the Allison 1000 five-speed valve body behind the 6.6L Duramax.
Towing with an LB7 or LLY Duramax, or the 8.1L gas big block, puts more heat into the five-speed Allison 1000 than almost any other light truck job, and the solenoids on the valve body live in that heat. When a 2001-2005 Silverado or Sierra 2500HD/3500 starts hanging the 1-2 or 2-3 shift, slamming into gear, or holding one gear in limp mode, this kit replaces all seven solenoids on the valve body at once. It covers OE numbers 8683167, D116420A, 29533074, 29533075 and 29536833.
The TCM never moves a shift valve or a clutch directly. It fires the three shift solenoids to position the shift valves, pulses the two trim solenoids to shape clutch apply and release pressure during each shift, and modulates the TCC solenoid to apply converter lockup. On 2004-2005 units a seventh solenoid, G, mounts in a separate modulated main pressure housing and drops line pressure at idle and during light-throttle cruise, which cuts pump load when the truck is not working hard. If any of these valves stops tracking its command, the TCM schedules a shift the hydraulics cannot deliver, and on a loaded truck that means slip, heat and worn clutches.
Start with a scan tool and note which code and which shift is affected. Converter lockup complaints deserve their own check: our Allison 1000 TCC shudder guide separates a weak TCC solenoid from a worn F-trim sleeve, fluid breakdown and a converter that is actually failing. With the pan off, the old solenoids can be checked for resistance and compared against the specs in our valve body testing guide. If the valve body itself has bore wear, a solenoid kit alone will not fix it.
Five-speed Allison 1000 and 2000 series only. In light-duty GM trucks that is the 2001-2005 Chevrolet Silverado and GMC Sierra 2500HD and 3500 with the LB7 or LLY 6.6L Duramax or the 8.1L, plus the Kodiak/TopKick C4500 and C5500 medium duty chassis that share the Allison. The listing range runs back to 1999 for the five-speed family. 2001-2003 valve bodies carry six solenoids and do not use G, so one part in the kit will be spare on those trucks; 2004-2005 units use all seven. The 2006-up six-speed uses a different solenoid set and a different internal harness, so check that you are on the five-speed before ordering, match the numbers on your old solenoids, or send year and VIN. Browse the Allison parts collection for the rest of the hard parts for this unit.
The labor is in the pan drop, not the parts, which is why shops replace the full set instead of chasing one solenoid at a time. Drain, drop the pan and pull the internal filter, then unclip each solenoid from the harness and unbolt the retaining brackets. Wet every new O-ring with clean fluid so it does not roll or pinch as it seats, torque the retainers to the factory spec, and confirm each connector clicks home. A truck that tows should get a spin-on magnetic pre-filter or fresh external filter at the same service. Refill with an Allison-approved fluid such as TranSynd 668, which meets the current TES 668 spec, then clear codes and expect a relearn drive cycle before shift feel settles.
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| Fluid required (not included) |
Doing this repair right usually means replacing these at the same time. Same transmission, ships together.
Yes, as long as the truck has the five-speed Allison 1000. The 2001-2005 HD trucks with the 8.1L used the same five-speed unit and valve body solenoids as the LB7 and LLY Duramax.
On 2004-2005 five-speeds the G solenoid sits in a separate modulated main pressure housing and lowers line pressure at idle and during light-throttle cruising. 2001-2003 units do not have it.
Sometimes. A weak TCC solenoid can cause it, but on 2002-2004 units a worn F-trim valve sleeve in the valve body is a common cause, and new solenoids will not cure that wear.
Most shops replace the set because the labor is the pan drop and the solenoids have the same heat history. A second failure later means paying for that labor again.
No. The 2006-up six-speed uses a different solenoid set and internal harness, and 2010-up valve bodies were redesigned again.
