Consider the following case file: 2007 XK (X150) presumably presented signs of an electrical short somewhere.

Situation: After driving at normal operating temperature for about 15 minutes I parked and ran a couple of quick 5 to 10-minute errands. After the third errand, when I attempted to start the car, the Jag started but quickly sputtered and died. I tried again; the same thing happened (RPMs barely reaching 1000 and dying in seconds). Waited for a few minutes, tried again this time depressing the accelerator pedal. Nothing. I repeated this process, letting it rest for 2-3 minutes in between each attempt. After about 7 tries (unlucky number) I reset the electronics by removing the battery cables. The car cranked up without a glitch and drove fine.

Important Details: The Dash Control Panel presented two error messages. #1 – Low Petrol, Navigations system will list fill stations (the digital fuel gauge displayed empty) and #2- Park assist unavailable, please consult local dealer. These conditions presented themselves with each restart attempt. The fuel pump produced the typical audible hum and the fuel tank is actually at full with the usual choice of petrol (Mobil 91 octane fuel). All other electronics apparently worked (sound system, windows, alarm system, locks, AC, etc.) EXCEPT for the boot/trunk; I had to use key bypass (further indication of an electrical fault).

Potentially Related Issues: I have had other presumable electrical issues with this vehicle. #1 - A rare cold start Gearbox failure (a total of three times) that goes away with a shut-off and restart. #2 – Also at cold start, sound system failure but only for the AM/FM radio. Radio antenna, CD, and Navigation all worked well and produced sound as normal. This problem went away after the car was shut down and allowed to rest for about an hour and has only happened once.

Suspect: Possibly an automatic car wash? All of these issues have come up a day or two after an automatic car wash that includes an underbody/under car spray or wash. As one drives into the wash, there is a moderately powered spray that rinses the entire bottom of the vehicle. Hard to believe, but so far it is the only thing I can think of that could affect this. Granted, this is a relatively new issue in the last few months but I have used the same wash many times times before and with different vehicles prior without any issues.

Based on what I’ve mentioned, Am I completely on the wrong track? Do you recommend I look into anything? Is there something I'm missing, perhaps a common issue?

I apologize for the long read.

 

Your experience is the reason why it's a bad idea to use an automatic car wash to clean the underbody of your car. It's can turn your car into the equivalent of a salvage-title flood car without ever having been in a flood. Electronic modules are everywhere and they're not waterproof. An automatic car wash is a pressure washer that forces water into places that splashes while driving in the rain don't get into. If you decide to do so anyway, make sure to drive your car at highway speeds for at least 15 minutes to dry everything underneath.

The same is true if you use a pressure washer to clean your engine compartment. You're looking for trouble.


P.S. Sure, you could do that back in the day. All you had to do was protect your distributor, ignition coil, generator, and voltage regulator from getting wet. That's not so easy with today's X150 models with separate coils for each cylinder and multitudes of modules. Of course, they're water-resistant but not waterproof if submerged or hit by a pressure washer. It's not a Land Rover that was designed to cross rivers, get muddy, and be pressure washed.

 

I pressure washed an engine once. Crap blew everywhere and it was a debacle. I've never done it since. The pressure from a regular hose does more than enough, especially using mild detergent and a soft brush with warm water.

 

How old is the battery ? Why not charge car up overnite ?

 

About two-three years old. It's an Interstate AGM Battery. I recently took it to get tested (about 3 months ago) and was told it was working fine. I also don't have a battery charger, lol. But I will take the advice and have it checked again.

 

Should be ok then , but these cars eat battery's lol most come on here we all say battery , could be a drain some were , but Iam with CJ I've been under mine more times than my wife feeds me and loads of exposed wires not taped up