Battery is brand new. Key fob battery is brand new. Battery bench tests at 13.1 and tests in the car at 13.0 after being connected and tightened and left alone for 6 hours.

Get in and push the ignition button, and I can hear the fuse panel behind the center rear seat clicking, but nothing works. Dash lights up and rolls through the errors below. No other cabin electrics respond at all (windows, radio, roof, etc.). Tail lights turn on when brake pressed. PO indicated that “ECU Module may have gotten damp”, possibly by leaky roof, but this is not a flood car.DSC not available

Park brake fault

Back tire pressure

Battery not charging

Transmission fault

Washer fluid low

Engine temp indication fault

Cats system fault

Ideas for next steps to troubleshoot?

 

Check the connections at the battery, and recheck voltage with a voltmeter.

 

Actually, 13 volts is too HIGH for a good battery. You need it load tested.

All the codes being in one shot like that points directly to the battery being no good. It's almost textbook.

 

Thanks, I’ll try to pull that battery this afternoon and run it back to the store to exchange for a different one. Fingers crossed.

 

Didnt make it to the store to swap batteries, but tested it again tonight. It was reading 12.7 in the car. Tried a hard reset. Retightened both terminal connections. Checked every fuse in the car, all 3 boxes.

No change. Still the same cycling of errors on the dash screen. No cabin electrical accessory power at all. Ignition button does nothing button cycle the dash on/off.

I’ll still try to exchange batteries with the store tomorrow. Hope that gets me somewhere.

 

Left the first battery on charge all day. Also bought a second battery. Have cycled through both batteries into the car over the last 24 hrs. Both read 12.6-12.7v on the bench. Same in the car once connected. Gave both a 6 hr wait time once connected in the car before volt testing again (same reading range) and trying the ignition button.

No difference. All the same errors still cycling through the dash screen. No cabin/accessory electrics at all. Blinkers work. Brake lights work. Headlights do not. No windows, roof, radio, or center console screen response or activity.

It seems the battery isn’t the problem. What’s the next play?

 

Maybe the PO was correct and the ECU is toast. Probably need SDD to check it out correctly.

 

That’s the disappointing realization I’m nearing. I bought it at a near nothing number, trying to save it from the salvage yard. I can do everything else mechanical and body on my own, but sending it to the local independent Jag shop for SDD work and an ECU replacement I guess is going to be pricy enough to put me upside down vs its street value…unless it works.

Decisions, decisions.

 

ECU (ECM in attachment) is under hood so don't get leaky roof reference. Check central junction box (BCM in SDD parlance) if you suspect water damage as that is central to can bus communications and start security authorization.

 

Wouldn’t the auxiliary junction box behind the rear seat be more likely a problem from roof water ingress vs the CJB down by driver’s feet?

 

Also, do the junction boxes function as “dumb” switches, ie can they be swapped between any vehicle as long as they are the same P/N, or is there something in them that has to be flashed to marry it to a new vehicle?

If they are plug-and-play dumb switches, there are a couple of XKs in local scrap yards that i can try to salvage the junction boxes from.

 

Been reading your various posts and it appears your primary focus is getting the car to start. While you suspect water ingress to be the cause of the issue I would suggest you do some serious wiring diagram analysis to check the circuits that initiate engine start. Trace back from the starter motor and see if you're getting a good 12V, given water damage is suspected be especially sure to see the vehicle ground points are not corroded to drop your 12V.

If my eyes don't deceive me the rear junction box (RSJB) shows some evidence of oxidation adjacent to several fuses. Have you removed all fuses, relays & connectors to clean any oxidation that might be present? Pay particular attention to those connections in the circuits that control starting and of course CAN bus communication.

Perhaps the most helpful advice would be for you to get all the fault codes stored in the car. This will enable you to focus on those modules/circuit that are preventing start. If you don't have a reader now is the time to get one.

I'm attaching some information on fuse boxes/relays, start/security systems and Jaguar (actually FORD) engineering part number nomenclature. Good luck.

 

Thanks very much Hafren, I appreciate the documents. The AJB is toast. There is corrosion as you saw, but the water is into the board and swelled it up in several places, so I'm afraid it's beyond cleaning. Even just a visual inspection showed multiple circuits that had been corroded through, in addition to the need to replace the board itself. I have already bought all new fuses and relays...not even going to try to clean the current ones since they are cheap enough to replace with new. I've got an AJB from a confirmed running car that I'm going to swap in, and a local shop is going to try to reprogram it, and the key, once I get it put back in. I do have a code reader to start tracing modules and testing specific circuit faults at that point, but this board was so shot, it wouldn't respond to the code reader with anything meaningful.

Should have the "new" AJB in and programmed in about a week, so will update what the picture looks like at that point. Fingers crossed.

 

Given so much damage to the RSJB you better verify your master fuses are good, adjacent to the battery. Also there are 2/3 modules alongside the RSJB that may have water damage, remove the seat backs to examine.