Allison 5sp: LB7 limp mode/abs/brake system/check engine light

bdflick43

TFlick
Nov 12, 2013
5
0
0
Im new to the forums so don't be hating but anyways I have an 02 lb7 and im having tranny problems... ill start it up and no lights will be on and it shifts fine... could go for two days or two miles then the speedo will start to bounce crazy and the check engine light will come on and it will no longer shift outa what ever gear it was in at the time... if I keep driving it the abs light and the break system light also come on... if I want it to shift I have to stop, shut it off, turn it back on then the abs and brake light go out but the check engine light will stay on.... most times it will shift then but really hard and the entire truck cuts out( runs like shit) and usually gets stuck in another gear within a couple hundred feet....let it shut off for a couple hours and start the process all over again! had a friend scan it with a snap on computer and found a bad output speed sensor code and a low fuel while enriched code... no other codes... put a new speed sensor in ran fine for a week then started doing this again... haven't had a chance to get the codes.... any ideas?? any similar stories?? could it be a week cp3 causing limp mode?? HELP!
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chevyburnout1

Fixing it till it breaks
Aug 25, 2008
2,368
1
38
Berthoud, CO
Sounds like two different issues. Your correct at suspecting the speed sensor for causing most of those issues though. Did the old sensor look damaged? Is there fluid in the transfer case? Check all the wiring associated with the speed sensor?

The low fuel pressure code could more than likely just be a fuel filter. The exact code numbers would help out though.
 

bdflick43

TFlick
Nov 12, 2013
5
0
0
I wasnt the one that replaced the old sensor but its headed to the shop tomorrow to get all plugs wires and sensors looked over and tested... found some people having the same issue and it turns out it was a bad sensor and wire on the transfer case