Hey all, so the problem occurred last night. I was doing a light pull on a open stretch of road and the car just started flickering lights everywhere In cabin (including headlights) and the car proceeded to take itself out of sport and seemingly put itself into neutral which at least allowed me to coast to a gas station at the end of the road. I had no tools on me but tried to start the car again only to be met with “sos function disabled”(or similar) and when pressing on the brake pedal the start button only turned the car off while in accessory/on position(Seems like car is detecting brake cause it’s proceeding to ask for button press which like I said just turns car off again). All the other electronics currently work. One thing I did notice is that the jaguar start button was not lighting up per usual with the heartbeat at all. Tried a jump start off a friend anyway and the button started to beat again but still produced same results. So I had to get it towed back home and read the codes which said U0001(87), U0402(00), and U0592(00). I’ve currently had it on the CTEK for the past 10 hours and the car is only on step 4 (when I went to sleep last night it was at 3). The car is a 2017 Jaguar F-Type Premium with Auto Trans, mods are VAP tune and pulley (I’ve been running this setup for the past year with no issues what so ever driveline wise). The only other thing I noticed lately prior to this issue was random headlight and electronic flickering but it was always short lived and I have never had the low battery Indicator appear. Thanks everyone as always

 

In light of the history you give (and no pun intended), the problem is with the battery and/ or the battery connections. The fact that the CTEK unit still has not taken the battery to a full charge is an additional indicator of the problem as well.

 

I've had batteries (well one) that took 24 hours on a CTEK to fully charge.

 

To put a soft ending on this story for now it seems like battery cause car just started with ctek hitting full charge. Gonna check battery in the morning but if it’s not all good with the multimeter I’ll pickup a new battery. If the alternator was the issue would I have a code? The battery was new as of 9/19

 

And make sure that the new battery is fully charged at installation. Do not take the word of the clerk behind the counter nor his/her use of a portable tester that pronounces the battery as "good" ( I speak from personal experience). Put the new battery on the CTEK to be certain that it is at full charge when installed.

 

I'd look very carefully at the connections. I had some interesting behavior when one of the battery terminal clamps was fully tightened, but not actually tight on the post. Since the posts are tapered, it's possible to tighten the pinch bolt on the terminal clamp until it's bottomed out, but not really clamping the post.

I don't know if the lights flickered, but the infotainment sure did. I suspected something loose so started wiggling all the major power cables I could find. Fortunately, it was only the second or third one I grabbed that was the culprit.

 

I’ll check the other connections but something I noticed before the battery reset I did was that the ground to chassis was super loose on the chassis part of the wire so I fully tightened it down with a wrench this time. I’ll check the posts themselves when I get off work

 

+1. I've had a shop guy lose a sale because he confidently pronounced the battery in a previous XKR "good" and refused to sell me a replacement. I bought a better one online for a lower price and all my issues were resolved. Beware "experts".

 

+1. Looseness or corrosion at the terminals or at the ground cable lug connection on the boot floor would cause that intermittent flickering.

 

I had a battery related problem in my Nissan 370Z that was traced to a poor connection between the cable clamps and the battery posts. One of the clamps was tightened down completely but barely made contact with the post. I had to shim it with a piece of soda can and then bought a set of battery post caps at the auto parts store. They are made of thin lead and slip over the terminals and then the cable clamps can get a good bite on the terminal. Very inexpensive.

https://www.autozone.com/batteries-s...B&gclsrc=aw.ds

 

So I ventured to looking under the ground cable and found some black on the chassis ground and backside of the meta on the cable so sanded it off and tightened it down very nicely we shall see, I still have yet to to check battery with multimeter, also perfect timing, in light of night starting a a new thread I need to get a annual service and I have a Pulley and Tune, will it be okay if I flash back to stock or will it give off a CEL (which I’m assuming they might investigate)?

 

No CEL as long as you keep it under 5000 rpm.

 

Any harm in leaving it and putting up multiple signs to not flash/and or update ecm lol, only asking because makes a difference on where I bring it. If I have to keep it under 5k I have to drive it to ocala myself (45min) but if I want it serviced at its purchase place in Tampa, FL (2hr) it’d be driven by another person and I don’t trust them to keep it under 5k lmao

 

I tried that at my dealer one time. The tech immediately responded:”Oh...you have a tune...cool!” If you go that route, tell them that they are responsible for bricking the ECU if they attempt to flash to it. Better yet, revert to the OEM tune and risk the CEL. At least this way, there’s absolutely no risk to the ECU.