Code 1637/1643/1000/passive security or a transmission lockout??
 

After only 2 1/2 weeks of joyful ownership of a 49K mile 2006 XK8 in otherwise excellent condition, it began to refuse to allow the starter to turn with the key in the ignition. All conditions were normal, but when I tried to go from 'accessory' to 'Start", nothing. The steering wheel would not move, the shifter would not move, nothing.
Moving the key back and forth, in and out of the slot, activating Key FOB on and off(lock.unlock), did nothing. The car had not been bumped, hit, jarred, etc. I called my local mechanic who gave me a ride to a meeting, and would come back to check it. He said that when he returned about 30 minutes later, the car had gone into "Reduced performance Mode". He moved it to his shop and would check it the next day. The following day it was 'reset' and back to normal performance, working fine!!?? It had set codes: 1637, 1643, and 1000.
Over the next 2 weeks similar problems happened 3 more times leaving me stuck at various locales around my little town, usually when I had set the lock with my key FOB. One time it happened in my driveway with the door unlocked when I just ran into my house for 5 minutes and had shut the car down for that time.
I finally reluctantly returned the car to the used car dealer as it was under the 30 day return warrantee. I asked that they try to find the cause, as I really wanted the car. Now after 3 months, the dealer has had the car checked by their mechanic, changing a brake switch which they "Think" might be the problem, but then they took it to the local JLR dealer for 21/2 weeks. JLR mechanics tried to duplicate the problem, and could not get it to return. Final decision is, ?????

I put this problem out in Feb/March in a similar thread to see if anyone had seen similar problem, and had no response. I am hoping someone might have had some experience with this. One local European independent mech. says he thinks it might be module in the steering column causing the key to lock out?
It also acts as if there is a transmission lockout (micro)switch that is slipping, preventing the starter from being allowed to turn at times??
In all cases, this situation has happened to me 3-5 days apart, and will 'reset' in 30 minutes to 3 hrs.
Maybe my car is Haunted??? HELP???

Intermittent starting problems are a PITA
 

Sorry to hear about your problems. Intermittent problems are the worst to try and diagnose.

in the thread below, posts 4 and 5, there’s “back to basics” info on all the systems involved in the start, including a link to Gus’ step by step walk through. I used this to get my XK8 going after it had been sitting in storage for 2 years.
https://www.jaguarforums.com/forum/x...97-xk8-217358/

By looking at what you said, I’m guessing it’s a break in the CAN bus wiring, or a hidden problem with the instrument cluster in the dash.

Try to get more info, when you next have the problem ie lights, sounds, ( or lack of) and post them here.

David, Thx for the reply. I checked the links and didn't see any that really addressed my issue, although they did help somewhat.
I have been driving the car for several days now with no problems(so far). I take it Wed. to an mech. who seems to think he has seen the problem in a Lincoln of the same vintage . Thinks the problem is in the steering column module.
As I have said, with the exception of this problem the car is in excellent shape, so I really want to get it up and driving. Everyone who sees it loves it. I took it to the local Jag dealer to get a spare key programed. When I went to pick up the key 2 mechanics and a salesman were standing around the car literally ogling it, and wanting to ask questions about it. Never happens with my F-Type.
Will see what the mech finds out.
Thx.

If it was me, I would look at fixing this problem in 2 phases: First, you will have to do what you have to do to get as much "data" as possible. Get a Jaguar-aware code reader, and use it every time something happens. Get as many codes as possible. Codes are your friend, easy to search by. Second, if these CAN messages keep coming back, it will be necessary to start getting more aggressive with poking around the CAN bus devices, starting with disconnecting them if possible. The electrical manual has a schematic of the bus.Disconnect anything not essential and see what happens as it relates to the main problem. Also, there is a funky twist-lock connector on the transmission that can be put back incorrectly, and even fill with fluid if the sleeve is not properly locked in place. If this connector is inserted wrong, the contact pins can be pushed back and cause intermittent problems. Keep in mind the TCM is located inside the transmission, so CAN messages have to go through this connector. Depending on cost and your commitment, you may have to send modules out for evaluation and repair, even blindly throw parts at the problem sometimes. Someone a while back had problems like this, and it turned out to be a burned out security module, apparently very obvious once the circuit board was exposed.

On the flip side, do not minimize the frustration of getting stranded and needing a tow. These situations have a way to interfere with real life (job commitments, picking up kids, date night, etc.) really quickly. Maybe it is time to cut your losses and move on. These cars are around, and even if in low supply, they are in generally low demand, too. Those late XK8/KXKR are the end of a long(-ish) evolution and should be as problem free as these cars come.

Best of luck, keep us posted.

The codes that were set(16337-43,1000), only happened the first time. Once reset they never appeared again. After the problem recurred 4 times and I returned the car to the dealer, he had it for a week before it happened to him. His mechanic traced out a 'brake release switch' switch that had previously been replaced, and appeared to have been installed incorrectly. It was replaced. After that the problem never recurred with the dealer. They then sent it to the local JLR dealer/mech. They kept the car for 1 1/2 weeks trying to get the problem to recur with no luck. Everyone thinks either the brake switched fixed the problem, it never happened, it "Healed itself", or "?????".
As I said, I will take it Wed. to have another mech run a diagnostic on it from his side of the road to see if he has an idea. I guess the more eyes that look at it, the better?? So far all anyone has really been able to come up with is curious looks, and more questions, just nothing definitive.
Oh well, WTF, over.....

Did you get to the bottom of it? My 2005 4.2S convertible does the same. Same codes. I suspect it may be low battery as it happens after not having driven her for a few weeks then do an hour's drive. Stop for a few hours, Drive a short distance (<5 miles) to buy something from the supermarket, come back 5-10 mins later - won't crank. Each time I have resolved it by getting a jump start, then resetting the codes when I get home.

The odd thing is when I connect a 2L diesel Passat it still won't start unless I start up the Passat. Something you are not supposed to do. So either the 2 batteries together are not enough or it needs the extra volage from the Passat's alternator - or worse, the charging current fixes the intermittent problem!

I have a multimer now. 14.7v when the engine is running - so alternator seems to be OK. Tested the passive drain. 0.255mA (when the boot light finally went out), so nothing leaking. But 0.255mA is about 16 days with a 100Ah battery, so fits with my timings.

I am guessing the 1 hour drive had just enough juice to start the car but only enough to charge for a 2nd start. Then the 2nd start pushes it below the min voltage limit and does not get it above in the short 5 min drive, so the 3rd start is dead. I will keep the multimeter in the car (along with my jump leads!) and test more if it happens again. In the meantime I will disconnect the battery when it's at home.