Not sure if this has been posted yet. Just received my 2017 XF-S. love the car but almost ended up getting t-boned when the auto stop killed the motor just as I was about to accelerate into traffic. So I decided to research how to disable it without cutting wires or setting a MIL light. Turns out on this model it's very easy. Open the trunk and on the right side there is a fuse panel door. Open and remove the door. You will now see the rear fuse panel. Just above the panel is the voltage module. You will have to look up from the bottom of the panel to see it. There are 3 plugs in the module. Disconnect the black 4 wire plug and secure aside. You will notice upon start up there will be an "auto start malfunction" message, and then after that, auto stop/start will always default to off. Attached at some pics of the module and connector. Hope this helps.
Voltage module

 

The message will say "auto start malfunction". Sorry, don't know how to edit thead.

 

Ok...

How did you figure that out?
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You dreamed of a big star -
He played a mean guitar -
He loved to drive his Jaguar...

So welcome to the machine

 

I own an auto repair shop. Researching the wire diagrams for that system led me to that part. Also, it was the easiest part of the system to access. I thought it might set a MIL, which I didn't want, or may effect other system, so I just unplugged it and tested it before posting. Amazingly, nothing else was effected.

 

So what is actually being disconnected?

 

The auto stop/start has a separate power supply coming off the voltage module. It used to use a separate small battery in the older models which you could just disconnect. They have since done away with that and now use a module. Unplugging it just disables that system. Everything else works. You get a fault message when you first disconnect it. Every time after that you just get the auto start off icon as if you hit the button to off. I have been using the car for 3 days now and no issues, no fault messages, no check lights. Everything else works including the remote start.

 

>I own an auto repair shop. Researching the wire diagrams for that system led me to that part.

Brilliant, thanks for you research and testing. This will, undoubtedly, become a recognized standard.

Cheers to you!
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Jaguar - it's not an automobile, it's a Motorcar
2015 JCNA National Slalom Champion Class M
Current: '08 S-Type 4.2 "Satin Edition" (250.06 whp / 259.67 torque)
Past: '05 X-Type 3.0/auto Jaguar Racing Green

 

Thanks for tackling this problem! I just spent 1/2 hour trying to get that plug out....no luck. What's the trick? It's hidden from view being behind the grey plug and what little leverage I could apply to pull it out didn't budge it. I tried pulling the trunk liner back to access it from the top but could only get it so far without major forcing and I gave up.

 

I will try it out today. I sincerely hope it will work.

 

Welcome to the forum Maximus75,

I've edited the typo for "auto start malfunction" in your first post.

Please follow this link New Member Area - Intro a MUST - Jaguar Forums - Jaguar Enthusiasts Forum to the New Member Area - Intro a MUST forum and post some info about yourself and your vehicle for all members to see. In return you'll get a proper welcome and some useful advice about posting to the forum.

Graham

 

Is that the main feed to charge the Eco battery as well? If you ever wanted to reverse the fact and connect the battery to try and avoid the msg in the dash, you might be in for an issue. Once the battery depletes for an extended period of time, connecting the battery will not always charge the battery but rather foul the cells and ruin the battery. Guess it's ok if you understand that doing so might require you to replace the battery at your cost if a dealer finds out about you disconnecting the battery...might want to keep that one a little secret or just connect it before going in on a service.

Not sure if it's worthwhile for anyone, but giving you all a heads up. We can actually tune the Eco Start/Stop feature to disable it from shutting off the engine..

 

As far as I know there is no "eco battery" in the X260. It uses the main battery for start/stop.

 

Yes, the main battery is used to provide power to the starter motor but not the accessories when the engine is shut off by the Eco feature.

It loops power from the aux battery, by disconnecting that connection your not allowing function of the aux battery which is there for the Eco function...thus I don't think it's allowing to charge neither when disconnected.

The aux battery is just in front of the main battery in the boot.

 

There is only one battery in the boot of my X260. I believe you're referring to the X250 model.

 

I just logged into Topix and in the shop manual for a X260 2016 3.0L it shows the aux battery behind the cover trim in front of the main battery(not under the spare but over to the right). Procedure 86.15.03 under section 414-01.

I don't have a X260 with me to check, just going on the Topix reference for repair procedure of access and location of the Aux ..although it does mention "If Equipped", so it's very possible Jaguar does this for different markets. I tried looking up the wiring but the english diagrams are not posted, presently showing unavailable on topix for english version.

 

 

This picture doesn't match what I have. My tire well is solid metal all around the spare with no access panels. I believe our discrepancy is caused by the build year. On another thread with pictures someone mentioned my (2017) battery compartment looked different than their (2016). When you think about it there is no sense in having a separate battery. Just cut out the function until the main battery is charged enough to support it. And that's what the system does.

 

Disconnecting the large grey connector with one black wire coming out of it produces the same result and it's much easier to access. I stumbled on this after giving up on the other connector that I just couldn't budge despite pushing in the release lever and pulling. I had pulled out the grey one to see if it helped get to the black one mentioned and forgot to reattach it. It's probably the ground for the stop/start control module given the size of the black wire. The Start/Stop OFF message behaves differently depending on how long the ignition has been turned off. From a cold start it doesn't show up until the system tries to activate it. A short time after you turn off the ignition it appears as soon as you start the car. HOORAY! No more irritating rumble or accelerator pause when taking my foot off the brake after forgetting to push the switch

 

Almost a week and no problems with the bodge. Automatically displays "No Start Stop" message about 10 seconds after turning the car on.

 

Stick your left hand in there and grab the wires and pull, then use your index finger to depress the tab circled in red. I just did this, came out easily.