Here's what my 2000 xk8 does; over maybe six months, it's maddeningly intermittent. Turn key, no relay sound ,no fuel pump sound, no start. Engine spins over like crazy, battery could start a tank. Check the Schrader valve, no fuel coming. Displays every unassociated warning you can think of. Sit and wait about fifteen minutes and she starts as if nothing had previously happened. No codes or faults stored. Back in the early summer it might do this a few times a month. For the past seven weeks it has not done it at all. I thought it had mysteriously fixed itself. Jags can do that, can't they? Then yesterday it did it twice... Car is driven daily, local and hiway. It is breaking my brain. Ideas? Thanks, Bob

 

Car intermittently not reading the chip in the key. That's exactly what a car with a key that is properly cut, but not programmed to the car will do.

Do you have another key to try with?

Take care,

George

 

I have another key, I tried it a few months ago, thought it still failed for me. I will try it again. Thanks, Bob

 

It may not be the key my friend. Don't forget these keys are "dumb" except for an embedded RFID chip.

All the detecting etc happens on the ignition column side. So that system may be acting up intermittently.

Unfortunately jaguar chose not to incorporate a "security" idiot light on the dash like ford / GM cars did that tells you when your key isn't recognized.

First things first. Do you have a bunch of keys on your key ring? Take them off - they may at times be pulling the key slightly away from the ignition. Second - when it DOES do it again. Make sure the key is firmly seated - turn the key to position 1 - how much wiggle do you have? The ignition cylinder may be worn and allowing a bit of slack.

Third make sure to apply a bit of pressure (I said a bit) inwards on the key when turning it.

Btw interesting useless fact. Any jaguar "timble" key - the actual manufacturer name will lock ANY jaguar. If you have more than one try it - or of you have a friend with a jag.

Take care,

George

 

I've bought a used key modual thingy. If we put it in, does the key need to be reprogramed?

 

Do you mean a remote, with buttons? If yes, it needs to be programmed, but not your key.

https://www.jaguarforums.com/forum/x...ers-faq-33580/

 

I'm not sure off the top of my head. I'd have to check the WDS and let you know on that one.

I believe the keys would probably have to be programmed to the new sensor using the WDS. Either by a dealer, or by an indy who has a WDS.

I don't think it's the electronics that confirm whether the key is in place or not that are the issue here.

It may be the "antenna" piece, which I believe is a wire ring around the ignition switch, or like I said an ignition lock cylinder (or worn key) that is allowing the key to slip out slightly. If the electronic module was bad, I doubt it would act up once in a blue moon. You would have a consistent no start condition.

Take care,

George

 

But it was on my 2005 VW Beetle. The problem was the fuel pump relay. It would work fine, then not start. It would get worse over time. The car would leave me across town. I would take the battery out take it home, charge it up, take it back and it would start. I found the location of the fuel pump relay, got a replacement and waited for it to do it again. When it did, I put in the new relay and never again had then trouble again. The relay is electromechanical meaning it can wear out. I hope that helps!

 

Bob - If the computer does not recognize the key the car will not crank at all. You say the engine is turning over so that is not the issue. It sounds like your fuel pump is working intermittently. No fuel at the Schrader valve certainly points to the fuel pump

 

I thought it was a fuel pump shutoff not a starter disable when the security system doesn't recognize the key - BUT the key is physically correct and will turn the ignition cylinder. I haven't Dealt with a key alignment issue in a while. I have to check the electrical diagrams to get a definite answer.

If you suspect the relay, pull it and see if the switched terminal is energized when the car is cranking but not starting. If the switched terminal has power, check for power at the pump harness. If you have power to the pump but no fuel then suspect the pump...

 

Another vote for check the fuel pump. Seen this in a few XK8s and no you don't usually get much in the way of codes stored. An xkec member actually had his XK8 towed from the Jaguar technical centre with exactly this fault.

 

Well any luck? Let us know how it is going!

trchaves