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Also, this went without saying and addressing, but you did check the fuse? Also for anyone reading later, if fuses are checked at some point and it's inadvertently put back in 180°off, car will give these symptoms.
I encountered the "Gearbox Fault" with code P1643 about a month ago while cruising on the highway. ('03 X-Type 3.0 with 91,000 miles)
When I got off at my exit, it seemed to be stuck in 3rd-ish gear. drove to destination, shut off, started again, same 3rd gear only response. Went to check trans fluid, and quickly discovered that in an X-Type, you can't - because there's no dip stick (what dipstick thought THAT was a good idea?)
Parked it for about an hour, started up again, and tranny shifted normally for the ride home. Inconsistent...
Past tranny issue in a Toymotor was resolved by a fluid flush. Had the fluid flushed, and the correct amount came out - about 3-1/2 quarts - all black and gunky looking after 15 years. Replaced with OEM fluid from Jag (at cost of about $40 per quart!)
About 2 weeks later while on a quick errand near home, same "Gearbox Fault" message appeared again. Same P1643 code. I did notice a momentary absence of lights on the J-Gate shifter this second time (and then they worked again after a re-start) - which others have noted as a symptom of a wet TCM problem.
Wanting to avoid the $3,000 cost of a tranny rebuild, I bought a used TCM on eBay for $85 and swapped it out. I waterproofed the new one with aluminum tape - just in case.
The one that was in there looks clean and dry. This time I'm going to wait a month to see if it comes back. If it does, I guess it's new tranny time.
In other news, it was riding pretty rough - so I put new struts all around, new front springs, new control arms and other bits about a month ago. She sits a full inch higher after that (the springs got saggy after 15 years) - and rides nice and smooth again. I also had to do the coolant tank again (previously replaced at 36,000 mi), a new belt, and other minor bits.
So I just put $4,000 into a car that's 15 years old, and which I could probably sell for about that much. But I do love this car, which is my daily driver for the last 9 years (and money is just money.) I also have a 2004 XJR - which goes like a scalded rat - but its a little big-n-boaty compared to the X, so the XJR only gets to go out occasionally on nice days (which is also a license preservation strategy.)
I'm crossing my fingers and hoping that the replacement TCM takes care of the tranny problem on the X-type. Otherwise maybe its finally time to go spend obscene amounts of money and look at an XE...
Thanks for this thread, just cleaned up some tracking in TCM
Sharing a huge thanks for this thread, my 04 X-type wagon 3.0 auto did limp mode for the first time yesterday. Scanned codes and P1643 was the only one (apart from P1000). A google search landed here. 20 uncomfortable minutes under the drivers side door well removing the wiper and TCM, I separate the unit and found tracking between riser pins to the connector. See pics.
mused a small stiff nylon brush to scrape out the tracking, reinstalled and tested. Seems fine, longer drive later will reveal if successful or not. Thanks again /carl Tracking on risers from board to connector Stiff nylon bristle brush to remove tracking More tracking on the right too, a bit more severe Cleaned up ready for reassembly, reinstallation and testing
After looking online for 20mins, I decided I'd try to remove the TCM and check it for water damage. I didn't find any water damage on anything related to the TCM, but I still cleaned it. After reinstalling it, I had the same issue. Locked in 4th gear, j gate not working, sports mode not working, and only being able to really gain power after accelerating for a long time in 4th gear. Any tips on how to fix this?
Hi Ethan,
Sounds like the car is definitely going into 'limp home mode' which drops engine power way down to protect the motor and trans while not fully paralyzing the vehicle.
The error code is very specific that it is a CAN Bus issue.
Have you thoroughly checked the continuity of the two wires that carry CAN Bus comms back and forth between the TCM and ECU?
Yellow and Green wires, EN16-123 and EN16-124 at your ECM connector.
There are two styles of TCM, a 16 bit verson that has a single large plug (JB131), and a 32 bit version that has two plugs going to it (JB230 and JB231).
The TCM wires to check is either JB131-34 and JB131-13 for a 16 bit TCM, or JB230-14 and JB230-15 if you have a 32 bit version TCM.
Check that each wire individually has continuity reaching from the TCM to ECM.
Check continuity between the two wires - proving they not shorted to each other somewhere within the loom.
Check for leakage to car earth as well.
If the wires have no detectable breaks, shorts to each other, or leakage to ground, and you cannot see any other physical damage to the loom that might indicate misadventure and a possible pinch point, then it is likely either the TCM or ECU has a problem.
TCM will probably be the cheaper first option, but I suggest you check out some other threads on TCM replacements, as there are several revisions of these within the relevant production.
From what I have seen the advise given on TCM replacement appears to be...that you should try to stay within the same revision window of your original TCM so as to not potentially have to reprogram anything else to accept the replacement module.
Have a good read on that subject, and if needed you might want to start a new thread to pose questions to obtan more specific advise and clarification on a suitable TCM replacement based on the labeling of your current one if you are going down the replacement track.
Hello Williams, I had same problem 3 weeks ago. Same symptoms and code as you. the J gate light were off. Story short, the TCM was the culprit. Had an automobile electrician fix the TCM and everything is back to normal now.
hay I know it's ben a time since ur post but yesterday I was extracting fuel out of the car i removed the gray 4pin relay trying to hard wire it up I shorted the positive and the positive together long story short it ended up disaster i have fuel pump monitoring system low input as known 1643 i checked the fuses all good but I don't have power to fuse 40 which is for the tcm here in lebanon no body know how to work in jaguar and I'm scared Amy help is excepted here is is a sample picture
see
08-29-2017, 07:30 PM
