08 4500 lmm no data

[mamu]

hey everyone. this will be a slightly long post but its necessary to get all the info out there.

the truck: 08 4500 4x4 regular cab auto. dpf/egr intact.

the problem: Customer apparently blowed a motor up (pipeline company). they had their mechanic pull the cab and motor. bought another motor out of ambulance and installed after switching everything over. Cab back on and nothing. They cranked and cranked and used ether and gas on rags but no start.

heres the fun part....scan tool won't communicate with gpcm or ecm. They brought it to me and i have it to where it will start and run but still no data. I even wired in a data plug at the ecm to bypass everything else on the data stream. Still nothing. I have schematics for the data from local dealer and from motologic. I have load tested all the data wires from the obd2 plug through the engine harness and to the tcm, bale connectors, gpcm and ecm.


Does anyone have any input or seen this before? Im at a loss rite now. Ive had a dealer try to flash in a new ecm with no luck. Ive called a few of the recommended businesses in the diesel world and looks like I've got the one odd ball job nobody has seen before. Any help would be appreciated!

 

[IOWA LLY]

Is the ecm in the truck the original ecm? Or the one from the ambulance?

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[THEFERMANATOR]

Is the ecm in the truck the original ecm? Or the one from the ambulance?

Sent from my SM-N920V using Tapatalk

Same thing I was thinking. Pretty sure the vans used different puns than trucks did for coms.

 

[mamu]

Ecm is the original from the truck. Supposedly everything ambulance related was removed and replaced with original parts. We have a new Ecm from dealer that's blank. They can't load a calibration in it because they can't communicate with it either.

 

[mamu]

my guy at the dealer said there was a bunch of codes in the ebcm and that it was possible that it was taking the data link down due to them. I've looked at the data diagram and the GM LAN wires don't go through the ebcm........could it be killing the Class 2 Serial Data wire and that be my problem?

he thought that his schematic from gm would be more detailed than the one i get from motologic. side by side comparison mine looks just like his, wire for wire and everything.

soooooo I'm open to any ideas and i may have left some info out so feel free to ask about simple things i could have missed or reach for the moon!

 

[clrussell]

4500 as in medium duty truck? What scan tool are you using?

To read a medium duty with my snap on tools I have to load it as a pickup in the tool.

 

[mamu]

i have tried to use a snap-on solus going in as a 2500 and 3500. but i have also used my efi live and tried to connect to the ecm direct and nothing.

 

[duramaxnate]

Was the Ambulance a truck chassis or a van chassis? Do you know the Vin of the vehicle the motor came from? and do you have the ECM from the ambulance?

EDIT: Do you still have the motor that came out of that truck originally?

 

[mamu]

i have no information from the ambulance. customer had his mechanic swap the motors out. all i have is the truck now with a running engine but no data communication.

duramaxnate: is there something your looking for? i might can call and find out where it came from and stuff. might get lucky and call the salvage yard and find some info on it.

 

[bmc1025]

Check and compare a van ECM pinout with a truck ECM pinout. Make sure the data wires are in the same place.

 

[mamu]

hmmm. did not think about that. ill see if I can find a schematic for a van and see what it says!

 

[THEFERMANATOR]

Also make sure the gpcm is plugged in. If the high speed lan isnt terminated properly at any module, it can go down. I remember makibu having problems with his, and it ended up being a gpcm problem.

 

[mamu]

i was thinking about this last night. should it matter if the data wires are in a different pin? I'm using the truck ecm, truck harness, and truck data plug. so it should be just like it was before they put the motor in.

i know that i can't communicate with the gpcm to get flow rates or anything. i tried to connect the GM LAN wires as to "bypass" the module but still didn't read. this top kick gpcm is a different plug than a 06 lbz truck i have in the shop. so i haven't had a chance to put another known good gpcm on to try.

 

[bmc1025]

It was unclear of what we are working with or what diagrams you are using. The topkick is a van body with a forward folding hood. I wasn't sure if the harness came from the topkick motor or the original engine.

 

[mamu]

sorry i thought i had made it clear that i was using all top kick stuff. i don't have any of the ambulance stuff or know anything about it.

 

[bmc1025]

No problem I think I was just confused

 

[mamu]

should be back on this around the end of the week. I'm tring to get a cummins isx built then i can go back to the top kick. so i haven't abandoned this rig yet.

 

[mamu]

alrite guys, I've load tested the wires from obd2 plug in the cab to the harness under the hood to the pcm, tcm, bale connectors and gpcm. all wires carry load and show to be good.

i can communicate with the tcm. but can't communicate with gpcm or ecm. the gpcm is first in line so I'm wondering if i can jump the data wires for the gpcm and see if it will communicate with the ecm?

any ideas?

 

[mamu]

i need to find someone who can flash a ecm/pcm on a bench harness. Ran my trouble shooting for the data stream. Found to much voltage on the data wires from the ecm to the gpcm. I have a new ecm/pcm thats blank and plugged it up then i have no voltage on the wires. So i guess i need someone to flash this new computer so i can see if that will fix it or if this is just a part of the problem.