Allison Codes

[rickdlance]

Towing 24,640 pounds gross with Juice on level 1. Uphill and strong headwind. Truck threw up code p1720, p0236 and p0700. Went into limp home. Tranny has transend in it and the temp was normal. Took juice off and it still did it. Let the truck set for a while and everything worked OK. Put Juice back on and towed the rest of the day. Any ideas?

[MAV]

P1720 isn't on my list of codes....

DTC P0236 Turbocharger Boost System Performance

DTC P0700 Transmission Control Module (TCM) Requested MIL Illumination

This is all I can help you with....

[Modified]

This is what I read, and don't know anything about it.

"DTC P1720 sets when the TCM detects an incorrect oncoming ratio, range to range, for an accumulated number of occurances".
This DTC indicates the on-coming clutch being controlled by Solenoid "A" is not applied or applied too slowly. This could indicate a leak or obstruction in a specific clutch or apply circuit. Check scan tool failure record for data for previous or current range information when the DTC was set to determine the specific shift when the DTC was set.
Important: Clutch failure due to installation of an engine power upgrade in not covered by Manufacturer Warranty. When engine HP or torque is increased over factory rating, a shift flare condition may occur.

Reference Helms 2002, page 7-874.

[dmaxalliTech]

There is a PI for a 1720 code, among others to inspect for burnt C1 clutches. Remove pan and check for clutch debris...