Trans ECU not talking anymore.

[Goodsy]

U1120 code
Cannot do anything like an auto reset or injector relearn (trans temp depandant)
Watching data from the auto is hit ans miss with comms errors all the time. With mut.

Any sugestions. New/ second hand trans ecu about $200. Might start with the loom.

Any suggestions I'm all ears (or eyes).

[old Jack]

Sorry Goodsy, I do not have the Service Manual for your Paj, so I do not know what you fault code is. However if it is a "communication" error it will be caused by a high resistance across one or more connection, and most likely a plug. Best way to check is to come in with your multimeter probes from the back of each plug and measure the resistance across the connected plug.
Circuit must not be live, so disconnect the battery/s and pull the multi pin connector out of the AT ECU. If you have a fault that you can reset and then re-triggers, then this will be an intermittent connection or connections fault which is difficult to find.

Best of luck.

cheers, old Jack.

[Goodsy]

Doesn't really effect the driving at all. I just cannot do certain things to the auto.
Still drives fine, but seems a bit reluctant to change down. Manual mode sorts that.

Fun Fun.

[Stoneman]

Do you still have your front CV removed?

AT ECU could read it as a malfunction.

[Stoneman]

This might help

http://pajero.2de.ru/22/html/M122110940002500ENG.HTM

[Goodsy]

Main ECU is not talking to the AT ECU. Comms error.
Either. Main ECU, AT ECU or a bad joint somewhere in the loom. Hoping for the later but going to be a bitch to fault find.
Has nothing to do with CV. They don't do much when stationary.

Thanks Nick. Have done a lot of reading. The U1120 code can be a bit of a red herring but I know where to start looking. Will run a can bus check this arvo
Also the center CD light flashes when stopped. Another clue.
As I said it's not stopping me and throws no cels just annoying.
I want to do an auto reset but cannot as the mut cannot connect with the AT ECU.

[pasniny]

the problem you have is can bus related


Terminator for the bus is astc ecu and combination meter.

make sure can lines are not shorted in any way

can you talk to atsc and imo ecu
can isn't completely stuffed as mutt can talk to engine ecu and thats done via can bus
looks isolated to transecu check the ecu

Trans ecu is under passenger foot well make sure its clean and not wet or anything

so on the first screen of the mutt the is can bus get see what it says

did you fit yr own tc lockup kit and tampered with trans ecu loom ?


Yann

[Goodsy]

Will test all when I get home.
As for the trans lockup kit. I have removed it and joined the only wire you have to break.
Was working fine. Will plug the mut back in and run tests.
Will report back! Did spill a can of coke in the passenger foot well. Will pull her apart again tonight.
ECU would be the easiest option. Only $180 for a replacement.

We'll see.

[Goodsy]

As a side note I still get all AT readings on the mut. All read ok but Comms drop out every 5 seconds or so and back to normal.

[Goodsy]

looks isolated to transecu check the ecu

Trans ecu is under passenger foot well make sure its clean and not wet or anything



Yann

This on the left hand side of foot well. Saves looking at the manual.

Cheers

[Goodsy]

Just ran a can bus test results below.

Big pic. Sorry



So where would you start looking for this? Learning the hard way here.

Where is NG?

[Goodsy]

No idea now. Acording to above I have a problem with my ASTC ECU and not the AT ECU connections.

Just did an injector relearn.
I see that under the system select that AT and TC are in the same system. Is this traction control or something different?



Also did a self diagnosis on the METER and ASTC. All good. NFI

[nj swb]

The terminating resistors help to keep the CAN bus "balanced" - I'm not sure they're essential to operation, but the system doesn't work as well without them. They're normally built in to specific devices on the bus, which in your case, appears to be ASTC and Meter.

The diagnostic checks you're performing are testing responses of the individual units, a sort of "challenge - response" test - the MUT sends out a certain command or query, and checks for the appropriate response.

The brains inside each of these devices is working properly, providing the appropriate response, so there's nothing wrong with them from that respect. But it is detecting something wrong, probably something like an unusually high error rate, which it guesses is an error with the impedance of the system.

As old Jack said, possibly a dud (high impedance) connection in a plug & socket somewhere, or it could be something (spilled coke?) creating an unwanted impedance path between two pins?

[Goodsy]

With the location of the ASTC ESC being in the center console and the METER ESC located god knows where I'm starting to think I've had this fault a long time and only getting a Mutt showed it up.

[Goodsy]

New symptom. ASC now kicks in at about 5k's an hour and limits throttle only.
Traction control working as normal. No other lights only car skidding light and no throttle.

Looking like an ATSC ESC atm.......