They are going to have fun with this.....

[ShadowsPapa]

This diagram is for a JL but the connections are the same for the JT albeit in different physical locations.

The systems mentioned in the litany of trouble codes reference the transmission control module which feeds into connector XY313A in the diagram. Check this connector and ensure all connectors are clean and seated. Add dielectric grease while you’re in there. Next check the CSCIP star can connector and ensure all connections are good and add dielectric grease. The drivetrain control module feeds into this connection. Finally check the XY291A connector in the passenger fender well and add grease.

Is the diagram problem on my end, or did it not make it? I tried a browser refresh, nothing there?

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[Sandevino]

Is the diagram problem on my end, or did it not make it? I tried a browser refresh, nothing there?

Looks fine to me but here’s the link - https://www.jlwranglerforums.com/JL-Wiring-Diagrams/CAN-C-BUS-LAYOUT.pdf

 

[AmishMike]

Good ole dielectric grease. I can remember TSB’s calling for Sabilant 22a, that stuff did work wonders.

 

[ShadowsPapa]

Good ole dielectric grease. I can remember TSB’s calling for Sabilant 22a, that stuff did work wonders.

Been using it and heat transfer compound (generally a white in color) since the first electronic ignition systems.
Without the heat transfer compound, the modules would fry, and without dielectric, you might not get plug wires back off, or the sparks could actually "leak" out of the boots and down the insulator of a plug or across the cap.
Late 1970s is when I first recall working with such things.

 

[ShadowsPapa]

Looks fine to me but here’s the link - https://www.jlwranglerforums.com/JL-Wiring-Diagrams/CAN-C-BUS-LAYOUT.pdf

Thanks.
It's bloody cold out now (it's been nice and warm, so 19 feels worse than it really is) so as long as this thing is totally behaving - I likely won't touch anything. But if the issue comes back as far as the module communications, I'll dig further.
The MIL isn't on, there was no dinging and it did fine this AM so either they fixed it and didn't write it down, or, who knows.
I did find it interesting that the service writer said "that's taken care of" but it's not written down or recorded on anything - yet - I had a pile of error printouts on the passenger seat. I figured just in case there was a question I'd point them to those. When I got in the truck, they were laid up on the dash on the right side as if someone had been in the right seat. Did they move the papers so they could access the area back of the glove box? LOL - likely I'm just hoping and trying to find indications they did something there. But I see no reason for anyone to take stuff off the passenger seat for a CCDIF relearn alone. They don't even have to open the hood for that as far as I know.

 

[AmishMike]

I hate not getting accurate repair orders!
When we do send something to another shop, I refuse to pay their bill until I get a printed RO. Yes, that makes sense but I had to fight with some of them to do this. They would just send a bill and expect to get paid.

 

[ShadowsPapa]

Everything fine again today. No CEL, no codes for communication......... that's not proof of anything really.....
But - I find it interesting that as my wife got in the truck tonight, she asked who moved the seat back and leaned the seat back back. I can't see why anyone would have moved the RIGHT seat or done anything at all with the right seat, or the papers that were in the right seat, unless they were accessing something over there on that side.
I'm still thinking they did more than just have the cam/crank relearn process take place. Isn't that done via connection to the OBD port.

 

[Rusty PW]

Everything fine again today. No CEL, no codes for communication......... that's not proof of anything really.....
But - I find it interesting that as my wife got in the truck tonight, she asked who moved the seat back and leaned the seat back back. I can't see why anyone would have moved the RIGHT seat or done anything at all with the right seat, or the papers that were in the right seat, unless they were accessing something over there on that side.
I'm still thinking they did more than just have the cam/crank relearn process take place. Isn't that done via connection to the OBD port.

Could be checking the grounds under the dash on that side.

 

[ShadowsPapa]

Could be checking the grounds under the dash on that side.

There's also the spot where all of the communications comes together back of the glove box area (Star CAN connector array?)
In any case, grounds, star CAN bus area, several cold starts and no communication issues.
I can't say "yeah, it's fixed" but I am seeing signs they actually did work in that area, and the last communications issues happened for the last 2 or 3 starts just prior to leaving it with them. In fact, it did the ding of CEL and the light was on when the door opened for me to pull it into their receiving area. I got there about 6:50, shut it off and waited. Their door opened at 7:00 and it dinged for that start.
It's been on several short errand trips since, multiple starts - it's very possible their guy thought "gee, we see this problem every month, I know what to do" LOL

That star bus connector is one place where all things seem to come together in a sort of star configuration to a central point. I could be very wrong, but the very name makes me think that is at least one central point where several modules catch the bus.

 

[JTRDistraction]

There's also the spot where all of the communications comes together back of the glove box area (Star CAN connector array?)
In any case, grounds, star CAN bus area, several cold starts and no communication issues.
I can't say "yeah, it's fixed" but I am seeing signs they actually did work in that area, and the last communications issues happened for the last 2 or 3 starts just prior to leaving it with them. In fact, it did the ding of CEL and the light was on when the door opened for me to pull it into their receiving area. I got there about 6:50, shut it off and waited. Their door opened at 7:00 and it dinged for that start.
It's been on several short errand trips since, multiple starts - it's very possible their guy thought "gee, we see this problem every month, I know what to do" LOL

That star bus connector is one place where all things seem to come together in a sort of star configuration to a central point. I could be very wrong, but the very name makes me think that is at least one central point where several modules catch the bus.

I've been having CAN bus and TCM codes with my diesel. I just got a call from the service department at my local dealership telling me that they are going to replace the star connector because all the issues are pointing to that connector. But if that doesn't work, they're going to replace my TCM.

I'm picking the truck back up tomorrow since they won't get the part for a week, but this is definitely better than the last two times when they said, "We can't duplicate the issue." I wonder if they replaced that connector since you said they were messing around in the passenger seat, but just forgot to document it.

Also, you said that the heat shield/electrical issues were with diesel, but i thought it was the gassers that were having that problem? I'll have to look back through the forum and see, but if it's the diesels that are having that issue, I'll keep that in the back of my mind for the future.

 

[ShadowsPapa]

I've been having CAN bus and TCM codes with my diesel. I just got a call from the service department at my local dealership telling me that they are going to replace the star connector because all the issues are pointing to that connector. But if that doesn't work, they're going to replace my TCM.

I'm picking the truck back up tomorrow since they won't get the part for a week, but this is definitely better than the last two times when they said, "We can't duplicate the issue." I wonder if they replaced that connector since you said they were messing around in the passenger seat, but just forgot to document it.

Also, you said that the heat shield/electrical issues were with diesel, but i thought it was the gassers that were having that problem? I'll have to look back through the forum and see, but if it's the diesels that are having that issue, I'll keep that in the back of my mind for the future.

I can't say what they did or didn't do - but whatever it was they did or didn't do was in the right side of the cab up front.
I've not had a single CEL or ding or issue since I got it back.

I'm really glad in your case they actually mentioned that part by name! Good for them (and good for you)

I got a "how did they do" survey in email and completed it with notes saying "they didn't document all of the work done nor directly address the CAN bus codes" or words to that effect.
It was a good visit, and if the result is that it's fixed, great - but I do like this sort of thing documented - on paper and online.
It may take some time to know for sure - but I have a good feeling so far.

Really glad to hear of progress in your case.

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