So hoping Steve P can do his normal magic but anyone else chime in. This car sets the check engine lamp every time it is started. There are no codes other than P1000 but when you wipe the codes with a scanner the lamp is extinguished. One then may drive it to the moon and no return--EXCEPT if you should have to switch the car off and restart--Bamm! There it is with no codes. So I think the battery is weak-ah heck I know it is but with a professional battery charger hooked up and set on 80 amps a start exhibits the same. So ideas?
Submitted by stevejag@sbcgl… on Sun, 08/10/2014 - 14:41
Submitted by SE98-32482CJ on Sun, 08/10/2014 - 07:32
Re.: 2001 XJ8 Check engine lamp
Steve as always thank you. Will run a function check on the brake lamp switch and get a battery. Had not thought about the "corporate' codes although I know they are there. Will advise.
Submitted by stevejag@sbcgl… on Sun, 08/10/2014 - 00:36
Re.: 2001 XJ8 Check engine lamp
P1000 is not a fault code, but an indicator. It indicates the codes have been cleared, but some or all of the component monitors the system runs have not been completed since. Codes are set when the various component monitors are run, if a test fails a code is set. Once all the monitors have completed and NO faults were recorded, the P1000 flips to P1111. One or the other will always be present.
George, one of two things is probably going on there. The most likely is the battery being junk, even if it will still start the car. A weak or failed battery can wreak havoc with a multiplexed car sometimes. And a battery charger can't make up for it, either. A battery is also a capacitor, and if there is a fault with it's capacitance, electronics can go nuts.
The other thing that is possible is some fault could actually be set during the starting of the car, and the scantool you are using may not be able to see it. Some codes are 'corporate' codes rather than OBDII mandated codes. They are discretionary for the manufacturer and some scantools can't see them. One such code off the top of my head is P1571. That is a code for the brake pedal switch. It can cause a Check Eng light, a Restricted Performance message or Engine Failsafe Mode message; and some scantools can't see or display it. So there may actually be something there when you read the codes, but you don't know it.
My vote is the battery though. I'd substitute it first.
Good luck!
Submitted by SE98-32482CJ on Sat, 08/09/2014 - 09:48
Re.: 2001 XJ8 Check engine lamp
Harold thanks but I should have said I tried that at 40 amps. Perhaps the battery is just too weak.
Submitted by hleggett@aol.com on Sat, 08/09/2014 - 09:07
Re.: 2001 XJ8 Check engine lamp
Edited on 2014-08-09 9:08:33
Assume, perhaps incorrectly, that the P1000 code is set on shutdown rather than on startup ... an experiment to validate this might be to hook up the charger while the engine is still running. Then, shut it down, wait, and restart. If the P1000 code is set, then replace the battery.
Best, Harold ...
I wasn't insinuating the P1571 was an issue for you in this case. I was using that as an example I could readily think of, regarding corporate fault codes.
Good luck!