Help with TCM....I think its fried

Drivetrain discussion including Transmission, Differential, Driveshaft, and related items.
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rcodea1
Posts: 22
Joined: Fri Jun 07, 2019 12:58 pm

Help with TCM....I think its fried

Post by rcodea1 »

All,

I am working with a '14 L77/6L80e setup. Trying to get the cer to start, but no fuel or spark as best I can find. Pulling the DTCs from HPtuners, this is what i see:

P0113 - IAT circuit high - should have cleared when i found and corrected the IAT sensor pins. confirmed its working correctly now
P0178 - flex fuel is not connected yet...assume this will not prevent the car from starting. correct?
P057C - Brake Pedal Position Sircuit Low - not sure what to make of this one. My harness has me connect a pair of purple wires to the brake pedal...12V when brake is applied. I have it wired as such. Maybe this is my real issue?
P0615 - Starter Relay Circuit - not sure here....its a standalone, so I think i can uncheck the SES and change to 'no error reported'. correct?
U0100 - Lost Comm with ECM/PCM A - not sure here...same as P0615?

I have cleared these several times, but the same ones keep coming up, and in the same order.

Any thought? Would at least one of these prevent the car from wanting to start? I am most worried about the U0100....Maybe i fried the TCM...but i can read/write to PCM, and can read from TCM (havnt tried writing to TCM).

Thanks in advance!

~Ryan
Charleston, SC
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~Ryan
Charleston, SC
PPV6.0
Posts: 34
Joined: Tue Jul 16, 2019 1:39 pm

Re: Help with TCM....I think its fried

Post by PPV6.0 »

Does the engine crank over?
Do you have anything other than the HPTuner plugged into the ALDL?
IS this a new problem?
Whey you say you can write to the PCM, does that mean you HAVE rewritten the OE program?
rcodea1
Posts: 22
Joined: Fri Jun 07, 2019 12:58 pm

Re: Help with TCM....I think its fried

Post by rcodea1 »

yes, engine cranks.
no other devices plugged into the ALDL...just the MVPI2.
its new in that the engine was running before it was pulled, and nos not run since.
yes, i have rewritten the PCM, making changes to make it a Speed Density tune, removing the DOD, eliminating DTCs, etc.
~Ryan
Charleston, SC
PPV6.0
Posts: 34
Joined: Tue Jul 16, 2019 1:39 pm

Re: Help with TCM....I think its fried

Post by PPV6.0 »

Can you talk to the TCM? Codes?
Have you tried without the HPTuner plugged into the ALDL? Its a long shot but I have seen where anything plugged into it will shut down the BUS!
I assume that this is a transplant into another vehicle?
If so, did you use the OE wire harness?
What changes did you make to the PCM program?
rcodea1
Posts: 22
Joined: Fri Jun 07, 2019 12:58 pm

Re: Help with TCM....I think its fried

Post by rcodea1 »

yes, i can talk to the TCM, and the only codes i am getting are the ones listed in my first post, the U0100 being the most concerning since i understand this to say that the PCM is not talking with the other CANBUS items...of which only the TCM still exists.

no, i have not tried starting without the HPTuners connected. I'll try it...and anything else at this point!!!

yes, translant into 71 C10, but should be irrelevent in this situation, unless the missing BCM, FCM, etc are required and cannot be worked around with the use of HPTuners.

no, harness is third party, but i confirmed the wiring against the 14 PPV diagrams...all checked correct.

i have tried 6 different iterations of cal file to this point. stock with VATS removed, speed density, stock with VATS removed and MAF forced fail, adjusting the MAP linear and offset , and a few conbinations of those. Though i cannot load the logs onto this forum, i have commanded upwards of 80ms/14% duty cycle and still no fuel out of the injectors. No wiring issues found, which leads me to believe there is a software 'idiot safety' that is not allowing the PCM to fire the injectors. I believe this to be related to the U0100 DTC, hence the question on the TCM.

so bottom line....
1 - Is the U0100 indicating a fired/blown TCM?
2 - Is there an 'idiot switch' which would prevent start, ie brake applied, CANBUS comm check with other modules, 'optional' Park/Neutral switch actually required, trans fuild temp/level/pressure data, etc?
~Ryan
Charleston, SC
rcodea1
Posts: 22
Joined: Fri Jun 07, 2019 12:58 pm

Re: Help with TCM....I think its fried

Post by rcodea1 »

got it to fire...seems it was an issue with how the MAF sensor was being failed.

this was with the trans in Neutral and no foot on the brake. seems my concerns were not founded. i was able to read and write to the TCM through the HPTuners without issue.

thanks for the assistance!
~Ryan
Charleston, SC
PPV6.0
Posts: 34
Joined: Tue Jul 16, 2019 1:39 pm

Re: Help with TCM....I think its fried

Post by PPV6.0 »

Awesome!! Glad to hear it!!

Post some pics of the truck!!
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