Allison 5sp: P0721

emkay

emkay

DIESELBOYZ member #2
Nov 2, 2006
31
0
0
Germany
Hi Guys,

I started my truck some days ago and the little bar under the PRND321 in the cluster flashed and the transmission released the gear. After some trys from N to D or 3 it worked well again. Same day on the highway the Service Brake System warning in the DIC came up but with no additional problems, turned off after stopping and starting the truck again. At home I read out the codes with EFI the other day and got the p0721 together with p0700, erased theman fine again. 2 days later same story combined with a "jumping" speedo and now Ally is stuck in 1st (and reverse available) and I have the Service Brake System warning in the DIC but no codes anymore??? I checked the VSS Sensor ad Output Speed Sensor reading with EFI and both are zero even when moving the car. Speedo is showing zero too (not moving at all).

I researched that there is a TSB (01493) that seems to handle this problem together with some other TSB´s (probably 3155 and 0574A) but I have no access to them.

So my question does anybody have those TSB´s, has anybody experienced the same problem and as prevention does anybody know where the sensors are and what are their part numbers?

Thanks

Mike
 
Kat

Kat

Wicked Witch of the West
Aug 2, 2006
17,899
13
38
59
Norco, CA
Could it be this?

2005 vehicles equipped with the Allison LCT1000 automatic transmission may experience range inhibit message, erratic shifts, poor shift quality, blown fuse "0" or any of the following DTCs: P0218, P0562, P0706, P0711, P0712, P0713, P0716, P0717, P0721, P0722, P0726, P0727, P0741, P0742, P0748, P0763, P0768, P0773, P0778, P0840, P0841, P0842, P0843, P0845, P0846, P0847, P0848, P0870, P0871, P0872, P0873, P0875, P0876, or P0880.

Recommendation/Instructions:
The condition may be caused by the power steering pump pulley rubbing on the TCM wiring harness. This can cause shorts to ground, opens and shorts to other circuits.

The harness should be checked for damaged repaired as necessary and routed away from the power steering pump pulley. This condition appears to be more prevalent on vehicles equipped with the 6.6 Duramax diesel.

the other codes lead to the injector harness problem
 
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