Sometimes No communication is normal

Bob Owner/Technician East Longmeadow, Massachusetts Posted   Latest  
Tech Tip
2010 Cadillac SRX Performance 3.0L (Y LF1) 6-spd (6T70)
No Communication
New Liftgate Module

Some new modules may not communicate with a scanner or show up on the buss until they are programmed. I believe this is most likely to be the case when they are slave modules.

I spun my wheels a bit on this one so I thought I would throw it out there for others who might not be aware. Usually when I install a new module I go right to programming and finish the job. If I had done that I would not be posting this right now. In this case, the customer had already installed a new module and said he couldn't get it to work. I told him new modules need to be programmed. He also told me the module had water in it, so before I tried to program I decided to scan all modules to see if there was anything else to be concerned about. 

Well, I saw a U0230 Lost comm with liftgate module in 2 modules. I selected the liftgate module in the scanner and I got a no comm error. From previous experience I have seen un-programmed modules communicate but display configuration codes. At this point I start thinking that there may be wiring or corrosion issues. After verifying power and ground and scoping the comm circuit, I told the customer he needed to get another module because this one was dead. 

After I installed the second one and had the same problem I knew I was missing something. After some discussions on a facebook group someone mentioned that this is normal until that module was programmed. I was skeptical but after some more research it looked like he was right. I went in this morning, fired up SPS and the module programmed with no problems.

I hope this helps someone else. Before condemning a non communicating New module, try programming first.

Dean Owner/Technician
Lakewood, Colorado
Dean Default

Thanks for the information.

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Brian Instructor
Parma, Ohio
Brian Default

Ford dual clutch TCM's , old school GM pdms & some ddms among others that I recall . Thanks for sharing this Bob.

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Marcos Diagnostician
Phoenix, Arizona
Marcos Default

You've seen it in the powershift TCM's? So if you guys run into this you still just try programming to rule it out?

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Kevin Technician
Winnipeg, Manitoba
Kevin Default

Seen it on other makes and models/modules Since were talking GM’s a couple come to mind Uplander EBCM’s.... some Canyon EBCM’s .

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Eric Owner/Technician
Edgerton, Wisconsin
Eric Default

I hate to be the one to say I told you so. ;-) Glad you got it fixed. Ain't learning new things fun?

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Bob Owner/Technician
East Longmeadow, Massachusetts
Bob Default

Yes you did. Thanks for chiming in. The thing I really like about the Facebook group's is the real time feedback. The learning can be fun as long as it doesn't hurt or cost too much. I'm still surprised that's the first time I ran into this. I have taken many programming classes and dont remember ever hearing this. Its something I'll never forget now.

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Rudy Technician
Montebello, California
Rudy Default

Bob- I read about this on iATN a few years ago. Stuck in my memory because I though it was very unusual.....

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Geoff Diagnostician
Lahaina, Hawaii
Geoff Default

Like Rudy, me too. Haven't noticed a pattern in the cases I've read. May have more to do with the supplier of different modules to the OE. If it comes without any operating system at all, it can't even say, "Hello! Please give me calibrations." :-)

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Daniel Technician
Courcelles, Quebec
Daniel Default

Thanks for the info. Very usefull.

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Rick Diagnostician
The Woodlands, Texas
Rick Default

Great Post Bob!! One of the things we always do is a complete module scan of the vehicle. I have seen numerous instances (mainly GM) where a module shows up under a different network address before programming so it displays the wrong designation. The one that comes to memory was a BCM that showed up as a second PCM when scanning all modules. HTH

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Miguel Technician
Collierville, Tennessee
Miguel Default

Thanks for the info

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Carl Technician
Baytown, Texas
Carl Default

I tried a PMI on a gran marquis Instrument cluster today. it was used but it powered up where the old one was dead. so I went to network test on my IDS and had no communication, so I thought maybe I need to program it like a new cluster. IDS programing stopped and said no comm. so now i'm testing my new(used) cluster. find out my terminating resistor is bad inside the cluster. I have not done…

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Caleb Diagnostician
Mishawaka, Indiana
Caleb Default

Wow good call. Just thinking out loud after knowing what we know would be this. Isolate the suspect module on the bus an check the comm waveform coming out of it only. That might help make a determination in cases like this. Or you could just program first lol.

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