allison trans codes

[ctryboy60]

I have a 2001 GMC 8.1l/Allison. Got in to go to work this morning and it didn't want to go into rev. After moving the shifter a few times I got it to go but the indicator light was flashing and the SES light was on. Going down the road it then would'nt shift from 3rd to drive until I shifted to N the back to drive. After work the SES light was still on but shift indicator wasn't flashing. At home after shifting back and forth the indicator started flashing again along with strange shifting. I pulled 3 codes: P0722-output SPD CKZT no/low signal; P1711-Trans SW E Stuck Closed; P1713 Pres SW REV CKT Malfunction. Do these codes tell specifically what is wrong or do I need to do further testing to narrow it down. I don't know if it has anything to do with it but we got snow this weekend and the roads were pretty sloppy yesterday . Thanks in advance for any advice.

[spackelman]

I have a 2001 GMC 8.1l/Allison. Got in to go to work this morning and it didn't want to go into rev. After moving the shifter a few times I got it to go but the indicator light was flashing and the SES light was on. Going down the road it then would'nt shift from 3rd to drive until I shifted to N the back to drive. After work the SES light was still on but shift indicator wasn't flashing. At home after shifting back and forth the indicator started flashing again along with strange shifting. I pulled 3 codes: P0722-output SPD CKZT no/low signal; P1711-Trans SW E Stuck Closed; P1713 Pres SW REV CKT Malfunction. Do these codes tell specifically what is wrong or do I need to do further testing to narrow it down. I don't know if it has anything to do with it but we got snow this weekend and the roads were pretty sloppy yesterday . Thanks in advance for any advice.

 

 

I have a 2002 8.1 / alli trans. I had similar symptoms (did not throw any codes), finally it would not go into gear. Repalced the park / nuetral switch located on the trans. All went back to normal. There is a bulliten on this subject.

 

When turing left in wet conditions, the tire spray would directly hit the switch and eventually corrosion does the damage.

 

Switch was about $170 from dealer, I installed it.