No crank no start no communication with ECM & TCM

Naabil Technician Tarkwa, Ghana Posted   Latest   Edited  
Discussion
Network Communications
2011 GMC Terrain SLE 2.4L (C LAF) 6-spd (6T45)
U0100 — Lost Communication With ECM/PCM "A"

Car was toed to my shop i Hook up my scanner and was able to access all modules excluding ecm&tcm. all fuses are good and CAN lines to the this modules are ok. customer told me engine was change a couples of weeks ago and the car got stuck on the highway.. so I’m suspecting loose ground connections to dis modules any help Will be much appreciated.... thanks 

0
Helpful
Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

So you answered your own question in your post. Yes you need to check powers an ground to the ECM an TCM to start with.

0
Default Ð Bounty Awarded
Naabil Technician
Tarkwa, Ghana
Naabil Default
 

Tanx

0
Default Ð Bounty Awarded
Nicholes Technician
Reading, Pennsylvania
Nicholes Default
 

Like what was already said , check power and ground at modules.

0
Default Ð Bounty Awarded
Ricardo Diagnostician
Plymouth, Michigan
Ricardo Default
   

Check your ground behind the a/c compressor on the right hand side of engine . The few I've been called for with that issue the technician forgot to tighten that bolt when replaced the engine

+1
Default Ð Bounty Awarded
Agree
Naabil Technician
Tarkwa, Ghana
Naabil Default
 

That ground behind a/c compressor has been well secured still I can’t communicate with the ECM/TCM module no crank no start ... I’m much grateful for you inputs

0
Default Ð Bounty Awarded
Joe Owner
Columbus, Ohio
Joe Default
 

Naabil Key off check the resistance at pins 6 and 14 at the DLC KEY OFF the reading should be 60 Ohms give or take a few Ohms the reading at these pins can help you get a game plan of where your going depending on the reading you get. You can do this with a break out box or by front probing or back probing the DLC, just be careful if your going to front or back probe, breakout box is the way to…

+2
Default Ð Bounty Awarded
Agree
Naabil Technician
Tarkwa, Ghana
Naabil Default
   

Pin 6 and 14 I had 121.6 ohms pin 4 and 5 are grounds and pin 16 I had B+ 13.4 volts

0
Default Ð Bounty Awarded
Phil Technician
Tewksbury, Massachusetts
Phil Default
 

If you have 121 ohms, then you have an open somewhere in the CAN network. There are two terminating resistors, one is internal in the ECM, the other looks to be mounted on the rear subframe to the right of the differential. I would unplug the ECM and throw a 120 ohm resistor across pin 39 TN/BK pin and 40 TN. If you now have 60 ohms across 6 and 14 at the DLC connector then you know it was the…

0
Default Ð Bounty Awarded
Naabil Technician
Tarkwa, Ghana
Naabil Default
 

Beautiful I will do that tomorrow while waiting for new Ecm .... much appreciated

0
Default Ð Bounty Awarded
Dennis Owner/Technician
Plymouth, Michigan
Dennis Default
 

Ricardo you working some where know or just doing your own thing.

0
Default Ð Bounty Awarded
Ricardo Diagnostician
Plymouth, Michigan
Ricardo Default
 

Hey Dennis just on my own

0
Default Ð Bounty Awarded
Caleb Diagnostician
Mishawaka, Indiana
Caleb Default
 

Not trying to be a jerk but this is a very confusing post. In your original post you say the CAN lines are ok. Then in the comments you say there is 120 ohms on 6 an 14. Someone else had to comment to tell you that means there is an open in the network. So clearly the CAN lines were never good. If I would have known that in your original post we could helped you immediately. How can we give you…

0
Default Ð Bounty Awarded
Scott Owner
Moreno Valley, California
Scott Default
 

Hi Caleb, Ah, I share your frustrations as well. Trying to fix a broken vehicle can be a challenge at times, even when English is our native language. Naabil did very well, considering how I would try & probably muck up conversing in his tongue. With that said - With anyone, sometimes the best response are leading questions. You said the spark was good, how was it checked? A screwdriver…

0
Default Ð Bounty Awarded
Naabil Technician
Tarkwa, Ghana
Naabil Default
   

i checked the voltages on the CAN and I hard 2.2 and 2.7 so I thought it was okay... from this network I found out the internal 120 ohms inside the Ecm was not responding that was making it difficult for me to communicate with the module .. much appreciated for everyone y inputs new ECM was put in it and programmed hence problem solved

0
Default Ð Bounty Awarded
Erick Mobile Technician
Bloomington, California
Erick Default
 

hey Naabil, i appreciate you posting these as i particularity just joined diag​.​net and have this same exact issue going on with a customers car. 2011 GMC Terrian 2.4 NO COMM WITH ECM/ TCM/ PWCM. customer recently replaced the transmission with a used unit and the car never started since then. Multiple mechanics have had their chance to crack this issue and replaced the ECM (used)…

0
Default Ð Bounty Awarded
Naabil Technician
Tarkwa, Ghana
Naabil Default
   

please mate sorry for the late reply I’m in Ghana does why. .. answer to your question? please no after installing Ecm to the car you will get the 60 ohms from pin6 &ampin14 and yes your scanner will be able to hook to all the modules without programming please and .. added to that you have to do online programming with j2534 box on acdelco site on ecm before the car will start and then you…

0
Default Ð Bounty Awarded
Erick Mobile Technician
Bloomington, California
Erick Default
   

wow Ghana, that awesome. thanks alot for replying and clarifying what i should expect to see with a new ECM installed. (60ohms). As this vehicle had 2 ECM replacements already with NO LUCK of communicating im left to believe we have an open circuit somewhere. I totally agree with you, i would never just change an ECM based off of 1 test as its always hard to condemn a bad module. I always double…

0
Default Ð Bounty Awarded
Naabil Technician
Tarkwa, Ghana
Naabil Default
   

Beautiful much appreciate: please recheck all the connectors on the engine unplug them clean & fixed them back again I hope you will start the car

0
Default Ð Bounty Awarded
Erick Mobile Technician
Bloomington, California
Erick Default
   

Happy Easter to everyone! Today i want to explain my thought process and results that i had gone through to diagnose this 2010 GMC Terrain 2.4 AWD with a No Comm with ECM/TCM/PSCM. Please bare with me as this is my fist post with in-depth information and as im relatively new with CAN LINE analysis. Back story: customer installed a used transmission and the car never started since then. Within a…

0
Default Ð Bounty Awarded
Naabil Technician
Tarkwa, Ghana
Naabil Default
 

Beautiful

0
Default Ð Bounty Awarded
Robert Technician
Trevose, Pennsylvania
Robert Default
 

Nice work

0
Default Ð Bounty Awarded
Scott Owner
Moreno Valley, California
Scott Default
 

Hi Erick, I'm glad you stuck with this until the conclusion! A couple of thoughts - "2. checked pin 6&14 120ohms (making me suspect an open circuit)." This comes from experience, but there's no suspecting an open circuit, you had one! That's one nice thing about electrical system testing, you can measure and know for sure, unlike some items on vehicles. Where's/what's that knock?…

+1
Default Ð Bounty Awarded
Robert Technician
Trevose, Pennsylvania
Robert Default
   

I have seen a few of these and similar vehicles where the engine installer didn’t have the connectors clipped all the way down on the ecm. But I see you found your problem already.

0
Default Ð Bounty Awarded
Joe Owner
Columbus, Ohio
Joe Default
 

Erick, Glad you found the issue! If you read through the response I posted to Naabil several months ago when he was dealing with a similar issue I listed multiple common areas to check one being bent or damaged pins at the PSCM or a damaged connector. I have had this happen multiple times during a transmission install or engine replacement and I’m called to a shop to diagnose the issue after…

0
Default Ð Bounty Awarded
Erick Mobile Technician
Bloomington, California
Erick Default
 

Joe, Yes! I did indeed took note of what you suggested with checking the connector at the PSCM. And even though it all look good from the outside; i had no idea the issue was INSIDE the connector WITHIN the insulation. MAN, It through me in a loop for sure. Definitely a case study ill never forget and will have in my archives for future reference. Thanks alot for the reply and words. I never…

0
Default Ð Bounty Awarded
Naabil Technician
Tarkwa, Ghana
Naabil Default
 

yeah sure the CAN connector to eps motor

0
Default Ð Bounty Awarded