I've got a persistent P1633 code that used to pop up when it was wet or after a wash. Now it's steady. Time to break out the multimeter and the dieletric grease.

I'll test battery, posts, clamps charging system etc. But I'd like to lube the pins on the computer. Where the hell is it?

 

And here I thought the forum wouldn't allow a 3 character search....

https://www.jaguarforums.com/m_26774/tm.htm

Ok it's under the cowl. I assume under the hood and behind the strut tower with 475 parts to come off. Any gotchas I could encounter Sunday morning when I get out to the garage?

 

What does a P1633 code indicate??

 

KAM voltage low. It indicates less than 9v to the brain. Car drives fine. Holds a charge just fine.

 

the pcm is under theglove box through the firewall where the pollen filter is, to access the elect conn remove wiper cowl and pollen filter housing, yep the big elect conn there is it below the housing, it has a security torx bit, disc batt neg, and disc wiring harness, clean with electronic cleaner(harness end) and inspoect for corrosion on conn and pcm. while youre ther eclean out the damn drain thats clogged up bottom left with 8yrs of leaves and debris. inspect the sealing portiot of the connector to make sure water not getting in there, also since you stated after you wash, I would emagine the wiper cowl is not sealed to the windshield base and allowing water to go down the firewall to the pcm and harness, either at the connector, or into the harness following the wiring in through the back. if after you do this it still does it, then check all grounds for battery and pcm grounds for .1vdrop or less if more youre loosing too much power, also pin the wiring power circuit with a dvom to verify no voltage drop there either

 

Damn, bone dry in there. 13.7 all across at the battery and still the code won;t clear. Lubed up all the batttery connections and hte PCM/brain connectors too.

Everything was clean. Stumped. And if I'm stumped the dealer will be for some time as well.