TRNW-2: 6t40 can bus diagnosing

[Michael Kneitz]

https://www.facebook.com/share/v/1HZRwPKqgX/?mibextid=wwXIfr

I’m in the same bout but I ran across this… little device looks interesting
and should be helpful when we get those communication codes…I think. I
haven’t bought it yet. Has anyone yet?

On Sun, Oct 19, 2025 at 12:52 PM Chris and Cathy Kershaw via trnw2 <
trnw2 at trnw.net> wrote:

> Mf3/mz0 lines are showing wires for vehicles with those rpo codes. Since
> mh8/mh9 shows a techm id say that’s how your vehicle is setup.
>
>  A vin would be helpful on something like this.
>
> The continuity situation you’re describing seems impossible to me. You
> describe having continuity through the tcm but not to the tcm.
>
> I’d back up a few steps, what modules communicate with a scan tool?
>
>  Don’t just do a full vehicle code scan but go to each one and attempt to
> view data. Often a no comm module will just show no codes on a full vehicle
> code scan.
>
> What modules set communication codes and what are those codes?
>
> On Sun, Oct 19, 2025 at 1:35 PM Justin Merritt via trnw2 <trnw2 at trnw.net>
> wrote:
>
>> Hello all,
>> I am working on a 14 Chevy Cruze 1.8 engine. I am chasing a loss of
>> communication of both the transmission and engine control module. I
>> struggle when it comes to testing wiring on the can bus lines, I just don’t
>> have enough experience with it. I’m determine to figure this one of for a
>> learning experience. I have included a diagram of some wiring I am testing,
>> and I have continuity between pin 29 and 6 and 43 and 14, but I do not have
>> continuity between 29 and 7 and 43 and 8. The diagram cuts off, but the
>> mf3/mz0 squares just loop around the tcm and back into the wires 6 and 8 of
>> the tcm.  Would I be thinking right that I have a break in the 2 bus wires
>> 29 and 7, and 43 and 8 that is causing my no communication?
>> Thanks for any help.
>> Justin
>>
>>
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