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For what it's worth, on mine 0x21 0x5c returned:

7E9 07 61 5C 0D D0 00 50 5A


That was with the engine off, however.
0x5A=90
90-50=40°C

Assuming it isn't 40°C/104°F in Colorado, was that after it cooled down for a few hours? It looks like a reasonable value if that was the case. I bet it matches the other trans temp pid(if you put it in drive so the other one works).
 

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Well that was disappointing, I thought LID0x5C was going to be trans temp without needing to be in a specific gear. I guess that exercise was a waste of time, it didn't buy you much over LID0x30.

I am not sure if byte C is gear selector but I think byte D is bitmapped PRNDL as it is displayed on the cluster. I am sure you will figure out A&B on a test drive.

FWIW, be careful venturing out in modes that aren't read only. If you are randomly sending commands, it is very easy to change a setting and turn your Jeep into a nice looking lawn ornament until you can have it towed to the dealer and reset.
 

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When you're talking to the CAN-D bus (the diagnostic bus via the OBD-II port), you are not able to electrically communicate directly with the CAN-C or CAN-interior busses. The TIPM module acts as an electrical gateway between CAN-D and the other two.
I don't think that is correct. I don't have access to a JK but other vehicles I have worked with that have the old gateway architecture pass CAN-C straight through to the DLC. If CAN-D were truly a separate network then it would require a termination resistor in whatever plugs into the DLC and that is a no-no according to SAE specs. I suspect if you have the ability to monitor broadcast messages, you will see there tons of messages coming through the DLC. There is no reason to do that unless the DLC is directly connected to CAN-C.
 

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I guess it is time for me to be quiet. My experience with other vehicles on the gateway architecture looks inconsequential. I look forward to seeing what you figure out.
 

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Remember, too, that the DLC is effectively a node in the middle of the CAN-D bus, so it doesn't need termination there. The TIPM is the termination point of the bus, internally.
Agreed but there should be 120's on each end of the bus. If the TIPM creates a separate bus then I would think there would be just one termination resistor there. At that point you would still need another, I don't know where that would be. Maybe they create a properly terminated bus completely internal to the TIPM where the DLC/tester is just a node. Either way this is the first gateway vehicle I've heard of that behaves like that.

I am definitely not doubting you. I thought my prior experience with gateway would be useful but apparently there are at least two versions of it. All I have to play with are powernet vehicles which do not filter anything at the DLC.
 

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You might be on to something there. One of those Mode$10 subfunctions might cause it to pass through messages.

I've haven't played with the Linux boards too much. I don't trust them to do only what I say and do it reliably. I like using Vector,Kvaser and ICS tools. They all work great and you can do some nice scripting for command sequences, plus they do a good job of datalogging.
 
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