I have 01 lb7 it started sliping and put me into limp mode when you WOT past 80mph. So I bought the Ppe stage 5 with ml converter. Had a transmission buddy put it together. When they finished it them and my boss drove it said it shifted through gears great. I got in it put it in drive it grabbed 1st for 3seconds then went to 4th and stayed there pulled the codes and got p1711 which is evalve stuck closed. Pulled the valve body and sure enough e was stuck. So used 4000 grit sand paper and polished the bore and valve put it back together and same thing happened. Pulled it apart cleaned up the bore put a spring out of 4l80e. Started it up ran through 1st when it was supposed to shift to second it locked in 4th said evalve stuck open. Have p1710 I believe. So we are stumped and this is my work truck so it's putting a financial strain on my family. Oh and we put new pressure manifold and new p/n safety switch and I'm using transynd fluid. Thanks for any ideas and help.
Allison 5 speed trans help please
- Thread starter 01duramx
- Start date
DBUSH had the same issue I think heres his thread http://www.duramaxdiesels.com/forum/showthread.php?t=51953
Hey guys, I'm new to the forum but man am I amazed at how many times that I have read through all the LB7 issues, and people keep getting directed back to the same old tired fixes. I have an 03 LB7 that is doing the same thing. I promise, it is NOT the NSBU switch. It is not the valve body. Chevrolet refuses to issue a TSB on the LCT Transmission wiring harness itself. There are known issues with the engine/body/computer grounds and a serious problem with wiring breaking inside the wire coating, causing an "Intermittent" LOW VOLTAGE issue. If the TCM does not have a steady, clean 12.5 or more volts, the transmission will go into "Limp" ( At less that 12 volts) or "Range Shift Inhibited" (At 11.5 or less volts) mode. The gear selector indicator and DCM may or may not issue a warning as the factory instrument clusters on these trucks are total poop!!!DO NOT COUNT ON THIS FOR DIAGNOSIS!! So far I have cleaned all the body grounds, traced the wiring harness with a schematic from this website, and wallah!!!, there it was. A wire broken inside the coating. Yea, it can get technical, but if I can read and understand the schematic, ANYONE can. Thank you guys for the help. The schematic saved me literally thousands in unneeded and unwarranted expensive not to mention time without my truck :thumb:
If you need to use the Sonnax tool let me know. E Valve bore issue has happened to me twice now and both times the tool was the fix. Both times it was right after an overhaul/rebuild. The good news is once you re size the bore it USUALLY won't stick again.
Ok update I put a brand new valve body in it.
Now I got a code saying the tcm needs to be
Reprogrammed because the computer does
Not recognize the high pressure since all the
New parts where installed so. The truck is at the
Dealer waiting to have the trech2 hooked to it.
So we will see what happens from there. PPE
Says that it has to have that done for the TCM
To understand that the higher pressures doesn't
Mean there is a problem. So we shall see.
Now I got a code saying the tcm needs to be
Reprogrammed because the computer does
Not recognize the high pressure since all the
New parts where installed so. The truck is at the
Dealer waiting to have the trech2 hooked to it.
So we will see what happens from there. PPE
Says that it has to have that done for the TCM
To understand that the higher pressures doesn't
Mean there is a problem. So we shall see.
I agree with Mike. I've built my fair share of Allisons, and I have never heard of this before.
I guess so. And there seems to be no end. Today
The guy working on it is gonna take the valve body
Back out take all the aftermarket suf out and change
The seperate plate to the one that has not had
The holes enlarged and see if the truck will shift
If it does than ghat would mean to me that
The parts for the a or b valves that Ppe supplied are
Defective.
The guy working on it is gonna take the valve body
Back out take all the aftermarket suf out and change
The seperate plate to the one that has not had
The holes enlarged and see if the truck will shift
If it does than ghat would mean to me that
The parts for the a or b valves that Ppe supplied are
Defective.