Possibly a battery on the way out, how old is it? 4 years is normal for a standard Jag spec battery.
KAM is Keep Alive Memory voltage it seems! Not heard or this WRT to Jags but had a search for you and found this -

Your code is caused by a lack of good connectivity between the battery and the Powertrain Control Module (PCM) ... or a failing PCM (Ouch!).

1. Check to make sure the battery cables are not corroded and tightly fastened ... both ends.
2. Look around the alternator for corroded/loose terminals.

It goes on to advise using "electolube" spray on the PCM connections.

 

Yeah I got the connectivity covered. The dieletric grease is smothered on.

The battery is of an unknown age. Bought the car a year ago and the voltage seems fine. Whomever installed it did not mark the little calendar on top of it. Dummy. Alternator it's not since it will chuck this code out with KOEO (key on engine off).

A battery is a $130 gamble but at this point I might take it. Multimeter says it's fine. I think the Jag electrics could be pretty fussy about the battery though.

I did have the alternator off in the spring to do the cam tensioners, but it's been doing this since may sporadically and now it's solid with the code reader unable to clear the code. A degrading battery fits the bill, but the voltage indicates otherwise.

Maybe I'll try Wal-Mart, buy a battery and if it's not the problem take it back and say it doesn't fit my car. Most places don't take battery returns though. Not cheap, I just don't see the value in having a perfectly good battery laying there.

 

If the battery is dodgy you'll sometimes see the instrument needles dance when cranking.

 

No dancing sadly, battery tested fine. Stumper.

I can see the bill at Jag now. 7 hours diag, no cause for fault found. Code not cleared and not repaired. $900 dollars please.

 

Where is the Keep Alive Memory battery ?

Is this the alarm Nicad, or the main ECU CMOS back-up as with computer mother boards etc ?

There is potential for this fault to hit all of us, so we could do with knowing where the battery is.
Is this the battery responsible for keeping the memory alive to store error codes etc. ?
Probably a common feature across the Jaguar range, and maybe someone who has done some module strip-checking might know.

Cheers .......... Graham.

 

From what I read it's in the PCM. Not just Jaguar specific as the searches I did covered all makes and it is an OBD code which covers all.
Hopefully some tech with more knowledge may have seen it and advise.

 

Whereabouts in the car is the PCM physically mounted ?

 

The brain is behind the glove box. Appears to be a real bugger to get out. Removed the connectors requires removal of the wipers, the wiper cowl the the pollen filter/holder/trumpet then the 3 connectors are uncovered.

Now as far as I know, the battery is the actual main battery for KAM. I've never heard of a small ECU battery fitted like on a motherboard. Ever.

 

Hi cosworth,

Thanks. Info now stored in my read only memory - until I lose my own connections that is (LOL).

From where you say this is, it would be worth checking to make sure everything is dry (hair drier hose) and connectors properly seated/ sealed behind there.

Also, these cars forget what they 'learn' about gearshifting when the battery is disconnected, so as you ask, does the PCM actaully have a battery ?

It is likely to have a programmable memory IC though, where internal charge retention can sometimes fail (rare), but other problems would be likely to arise if that happened and that would require IC or control unit replacement.

Did you try dissing the main battery for a while ?

Cheers ......... Graham.

 

I've noticed that the light is off when started, but the engine light come son after about 15-20 seconds after it has started.

13.7v idling, 12.2v first thing on the morning on the terminals.

Funny, can't find anything wrong with it.

 

Well I tried a brand new battery. Still the code persists.

Interesting though, the new battery I guess was sitting on a shelf for some time. It was reading 10.3 volts. So I drove around a bit. If you turned off the engine for say 10 seconds then did a KOEO test the code would clear. KOER test, the code came back right away. After I charged it up to 12.5v after a 20 minute drive, the code would not clear at all (KOEO or KOER) and the idling voltage was the same at 13.7. that was weird.

At this point I think the PCM is dead. NOT a cheap fix.

 

Yep, crap.

P1633 Jaguar Main processor unit failure malfunction

That's the jag specific code. I guess I'll be looking on ebay for one of these.

 

Ha!. Stealers reset the code for free on my oil change. Seems my little code reader can't kill off all codes successfully.

Jaguar/Land Rover of Richmond comes through. Saved me $200 for a new ECU that I didn't need.