2013 XK
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Joined: Aug 2010
Posts: 10,094
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From: Atlanta suburbs
Charger: Schumacher
50 amp Engine starter
10 amp booster
6<>2 charge maintainer
Measuring voltage: pressing pins on my tPi volt- Ohm meter to the battery posts
Battery charger clip/connectors: Positive connector clipped to post accessed by removal of the panel on the left side of the vehicle.
Negative connector clipped to post on the right side of the vehicle.
...
Ed
50 amp Engine starter
10 amp booster
6<>2 charge maintainer
Measuring voltage: pressing pins on my tPi volt- Ohm meter to the battery posts
Battery charger clip/connectors: Positive connector clipped to post accessed by removal of the panel on the left side of the vehicle.
Negative connector clipped to post on the right side of the vehicle.
...
Ed
All 5.0L X150 models came from the factory with a Battery Monitoring System module attached to the negative battery terminal. Attaching your battery maintainer's negative pigtail directly to the negative battery terminal with the BMS module probably bricked that module. You should have attached that negative pigtail to a chassis ground.
There is an important difference between the 4.2L and 5.0L models. The 5.0L models came from the factory with a Battery Monitoring System module attached to the negative battery terminal. It's complicated, but simply put it controls how and when your battery is charged to maximize battery life. When that module is working properly, voltage fluctuations can make it appear to be wonky, but it's not.
Never attach anything to that negative battery terminal; instead, use a chassis ground. Otherwise, your BMS module can be damaged and your battery won't be properly charged, which can result in a shorter battery life. 4.2L models don't have that BMS module. (My 2013 XJ 5.0LSC has the BMS module. Since I don't drive it daily, I keep it on my CTEK MUS4.3 using the alligator clips with no problems.)
See these threads for more information about the BMS module:
https://www.jaguarforums.com/forum/x...change-241034/
https://www.jaguarforums.com/forum/x...talled-277608/
Stuart
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Joined: May 2013
Posts: 2,351
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From: Florida
Perhaps he did have a memory holder. He was very well equipped.
From what I've read, Hard Reset probably would have worked. However, my judgement is that it would have been overkill--- the nuclear option. What the AAA tech was very simple and harmless.
I want to add that I was extremely surprised and impressed with how much experience with Jaguars this tech was. AAA uses local service providers and chose one that had Jaguar experience.
Once again, thanks to all who have participated in this discussion.
Ed
From what I've read, Hard Reset probably would have worked. However, my judgement is that it would have been overkill--- the nuclear option. What the AAA tech was very simple and harmless.
I want to add that I was extremely surprised and impressed with how much experience with Jaguars this tech was. AAA uses local service providers and chose one that had Jaguar experience.
Once again, thanks to all who have participated in this discussion.
Ed
Senior Member
Joined: Mar 2025
Posts: 366
Likes: 234
From: Indialantic Florida
Following advice of several XK/XKR Forum members, I called AAA. Within an hour a local AAA service provider arrived with a new battery. He went through the same basic steps I had been following, i.e., measuring voltage at the battery posts with point-tips on his tester. Voltage was within range. Then he did a couple other tests and said "There's nothing wrong with this battery."
Then he told me to get in and try to start it. I dutifully got in and did as he said. Same old same old. The gear shifting post did not pop up.
He asked me to pump the brake pedal a couple times, then hold it down firmly. Then he told me to press the Start button. It didn't work.
He then asked for the key fob. He clicked the Unlock button a couple times in rapid succession, then held it down for a few seconds. Then he said "try the Start button now." Lo & behold, it immediately roared to life!
He loaded his gear into his truck and told me to take it for a "spirited drive," which I happily did!
Note: I think my description of the process above is correct, but my short-term memory isn't what it used to be. I will have to try it a few times to be sure
Ed
Then he told me to get in and try to start it. I dutifully got in and did as he said. Same old same old. The gear shifting post did not pop up.
He asked me to pump the brake pedal a couple times, then hold it down firmly. Then he told me to press the Start button. It didn't work.
He then asked for the key fob. He clicked the Unlock button a couple times in rapid succession, then held it down for a few seconds. Then he said "try the Start button now." Lo & behold, it immediately roared to life!
He loaded his gear into his truck and told me to take it for a "spirited drive," which I happily did!
Note: I think my description of the process above is correct, but my short-term memory isn't what it used to be. I will have to try it a few times to be sure
Ed
It is interesting that THIS method of getting out of this locked phase hasn't been in the Forum before?
Or did I miss it...
I actually accidently did this to unlock the system..didn't know what I was doing...got lucky
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Joined: Jan 2015
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From: Naperville, Illinois USA
Not in the 10+ years I’ve been watching this forum.
Senior Member
Joined: Mar 2025
Posts: 366
Likes: 234
From: Indialantic Florida
There is a post where I first heard of this..
not too long ago.....
was about a "double" security lock....
Senior Member
Joined: Mar 2025
Posts: 366
Likes: 234
From: Indialantic Florida
Talking about two separate things....
Not double locking the car
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