I have a 2003 X-Type Jaguar 3.0 AWD and I have been trying to figure out how to fix it. I have error code p1643 witch I know is the CAN network fault but I don't know if it's my TCM or ECM or even the harness that's failed or failing. I can still drive the car but it's like it's only driving in I think 3rd or 4th gear. I have check engine light and gearbox fault light. No water damage to either of the modules seeing as I took them out to examine them and found no traces of water damage. I'm at a stand still because I don't know what to do to fix it. It's annoying driving the car with slow acceleration for 30 seconds until I can get some speed. By the way, no reverse lights and cruise control doesn't work either. Checked fuse 62 and it's fine. Any solution that y'all might have?

 

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.

 

How are the j gate lights supposed to work? I have illumination when I have my headlights on. And how much did it cost to fix? And am I gonna damage the car if I keep driving it how it is?

 

The J gate light only illuminates on the particular gear you are on. So if you are on drive, D illuminates. Then also check to see if your Sports mode button still illuminates when pressed as mine did not when i had the problem. As for cost, I am in Nigeria but it translates to about 100 dollars. But i am sure over there you probably would be adviced to replace the TCM than fixing.

 

Oh okay, my sport button doesn't light up and it doesn't light up what gear I'm in either. So obviously it's the same problem you had. How do I go about getting it repaired rather than get burnt by Jaguar dealer in replacing it?

 

No idea how things work over there. But if you can ask around for an auto electrician, Thats your guy.

 

I'll have to look around because I'm not trying to have Jaguar burn me for my money. Lol. Anyways, thanks for the help. Very much appreciated!

 

Water intrusion is one of the most common reasons for failure (fix before repair or replacement). Some folks have removed, cleaned, re-installed with success, others it's fried. If you get a used one, make sure it's off the same engine size (i.e. 3.0 = 3.0 or 2.5 = 2.5, etc.) and no re-program is required. Here's a video of waterproofing the unit and also location.

 

I thought it was required to have it programmed regardless of it being off of another car even if it's the same as mine. I tried cleaning the harness and where it connects to the TCM and nothing changed. Did the same for ECM.

 

 

Oh okay, I understand what you mean now. I'll try taking the TCM apart and cleaning it first and if it's a no go, I'll start searching for a new TCM that matches mine and hope for the best

 

Took apart TCM completely and cleaned it thoroughly with electrical cleaner, saw very small spots where water might have actually got in, but it's so small, still cleaned every spot of the TCM though. Hooked it all back up, started the car, I cleared the codes with OBD2 reader, check engine light went away and gearbox light stayed on. Drove around, turned the car off and back on again and check engine light was back, this time I have the same code P1643 and now I have P0420 P0430 now too. Witch I believe is either o2 Sensors or my cats are bad. I could be wrong, not sure. I'm worried that driving it around every day is gonna mess up something else. Don't want this beautiful car to go to waste. Lol

 

What numbers on the TCM have to match if I were to replace it? Mine says 1X43-72401-LA. Are those the numbers that need to match? Or do all numbers need to match?

 

New, rebuilt or repair of TCU, located in Pennsylvania =

https://www.autoecmcomputerexchange.com/

My assumption is the end letters mean little as long as you make sure it's from same engine 3.0, etc. But a phone call to the above could definitively answer that.

 

Hello William, Like the other guy said, Check and be sure you dont have a bad seal at the cabin air filter so you dont run into the same issue again after replacing the TCM.

 

if the TCM is inside the car.... how does it get water inside it ???

 

If you have a leak from the Cabin airfilter housing or a clogged sunroof drain pipes. In my case i had both.

 

So Im for sure having a TCM problem right? I don't wanna spend money on a TCM if I'm not 100% sure that's what's causing my car symptoms. I found a TCM with the same numbers as mine to replace it with. Haven't bought it yet though.

 

So in order of least invasive (lol) to most for this problem =
1. The old "bad or weak battery", personally hate hearing this for every symptom, but sadly it is true at times.
2. Battery cables and connections.
3. Wiring to and from TCM.
4. Interior corrosion or broken/loose solder points in TCU.
5. The TCU = MOST COMMON and the significant symptom shown of non lighting of gear you're in/sport button.
6.The ECM (very least common).
I also read in another forum, that ECI in Tennessee will take your module for testing for a fee, if it tests bad, they will apply the testing fee to repairing it.

 

Battery is brand new, cables are good, they seem fine seeing as I'm running a lot of stuff in my car anyways. I see very little water corrosion on TCM witch I cleaned to the best of my ability, water damage was on TCM plug port and a little bit on the motherboard itself but damn near not noticable, as for the TCM wiring, idk what to look for if it's bad. My gears don't light up at all what gear I'm in, it only illuminates when my headlights are on and every gear is lit up when I do that, as for the sport button, that doesn't illuminate either. I remember going through a car wash one time, at this time my car already had the gear box fault light on and check engine light, and after I went through the car wash I drove home, turned the car off and it wouldn't start after that, everything worked inside the car though, lights, radio, subs, literally everything, except it wouldn't start. I go to turn the car on later the next day and it started right up. As if something on the inside got wet and had to dry out before starting. Witch brings me back to the TCM. Would a wet TCM cause the car not to start?