HEY GUYS. MY OLD MAN HAS AN 01 K3500 WITH THE 8.1 AND ALLISON 5 SPEED AUTOMATIC. IT IS THROWING A CODE P0700 WHICH IS A TRANSMISSION CONTROL MODULE FAULT. I WAS WONDERING IF ANYONE (ARGON) KNEW WHAT THAT MEANT AND WHERE I SHOULD START.

THE TRUCK RUNS FINE MOST OF THE TIME BUT EVERY ONCE IN A WHILE IT WILL GET STUCK IN WHAT I THINK IS 3RD GEAR. NO REVERSE NO UP OR DOWNSHIFTS. TRANNY TEMP NEVER EXCEEDS 200-220 DEGREES


THANKS

 

Well...you need more info...This sucks,I know...but here goes..

ONLY ALLISONS use a seperate Tranny control module (Tcm)....So,when the TCM sets a code,it alerts the PCM that a code exists.The PCM then turns on the ses lamp.But going into the PCM,all you get is a po700,which means you should go check the TCM for codes.
Its just an FYI code,directing you to the TCM for diagnosis.

Did I make any sense??

 

YES BUT WHERE IS THE TCM, CAN I READ THAT SEPERATE, IS THIS A COMMON PROBLEM

 

The TCM is mounted on the fan shroud...I DOUBT an Autozone or whoever can read the TCM...It wouldn't hurt to ask...how did you read the pcm?


Again...you've just read the PCM,and all that p0700 means is,there is a code in the TCM...so you need to go to the TCM and find the REAL TRANS FAULT CODE....It may take a dealer or indy with more advanced software to retrieve a tcm code.

 

FYI...the Check-engine light only comes on for pcm codes...most scanners ONLY get a pcm code..

There are maybe 20 modules on a modern car that can set codes...

PCM (powertrain control module)
TCM (Trans)
Radio
Instrument cluster
DDM (driver door module
Pdm (passenger)
Seat modules
Remote keyless modules
Tire monitor modules
Dvd players
Onstar
XM radio
ABS
Airbags
Electronic suspension

All of these and more set codes...but most cheap scanners ONLY read the pcm....A tech 2 from Gm does it all...to the tune of 5 grand.
So,Gm has started ALERTING the pocm when some of these other modules set codes....This is what that p0700 means...It only means that the TCM alerted the PCM to a code...The TCM must now be communicated with to find the actual fault code

 

GOT IT. A GUY I WORK WITH HAS THE NEW SNAP-ON SCANNER. WHERE DO YOU PLUG IN TO READ THE TCM CONTROLS

 

Its the same plug...same plug reads all those modules..the scanner software hopefully has a menu to go to the tcm

 

ok het thanks a lot for your help. appreciate it. one of my buddies from high school works at the local chevy dealership so im gonna bring it there. he has access to the tech 2 scanner. thanks a lot!!!

 

Cool..let us know what the code is