Old Mike had a writeup in a thread on nearly the same issue about a year ago. His problem was the brake switch; his writeup had an excellent description of the replacement effort including pictures. On Range Rovers, this problem is almost always the brake switch.

 

Jim, I read Old Mike’s thread and then went out to run an errand. I left the cruise switch OFF (I have always left it ON), and I did not get any “check rear lights” or “engine failsafe mode” warnings in a 10 mile roundtrip…… I do still get “check rear lights” when I brake, but I think that is a different module.

I’m going to run the brake lights off the trailer circuit for now so I know I have all 3 functioning brake lights while I do more investigating.

Mike

 

No mike, that is just more information indicating the brake switch failure. Cruise control power runs from the switch on the center console, through one set of micro switches in the brake switch, to the ECM. If you turn on the console switch and the brake switch is faulity you get that message.
Likewise, if you step on the brakes and the brake switch is bad you get the 'check rear lights.
The cruise control microswitch is normally closed, opens when you step on brake pedal, the reverse is true for brake light microswitch.

 

Sounds reasonable. Any idea why it would be intermittent though? And when I was driving home today I tried engaging the cruise switch, but it did not throw a code…..

The brake light failures were odd and intermittent, too. What seemed to happen all the time was the passenger side (right) brake light did not come on at all. I checked the bulb, board, and harness connector with a meter. The bulb and board are good, there is just no power signal on the harness wire when the pedal is pressed. Occasionally, the driver side brake light stays on when you press the brake pedal, and does not go off. I can’t seem to find a pattern or reason to this.

I went ahead and made a harness (cut the brake light wires and fed them power from the trailer circuit) to feed both brake lights from the trailer harness connector today. Now I have three functioning brake lights again while I worry about troubleshooting the brake switch. Obviously I still get the “check rear lights” code when I press the brake pedal, but otherwise no codes. I’m thinking one of the driver chips in the control module is toast, so I may have to deal with that. Is there some way to “fool” the system and not get the “check rear lights” code when driving the brake lights from the trailer relay? Or does the system need to “see” a fully functioning module upstream?

Thanks,

Mike

 

The brake light switch is still going to cause a code because it connects to the ECM. But your problem does sound a lot more complicated than just a brake light switch fault.

 

I’ve kept the cruise switch off and so far after ~75 miles of driving no codes! It’s been so long since I haven’t had an error light and code of one type or another I forgot what it was like to be able to see the odometer or average mpg, lol.

I ordered a new brake switch which should be here tomorrow, and hopefully I’ll install this weekend. Thanks for all the help, I appreciate it. I can’t wait to have my cruise back……

Mike

 

Short-term update:

I bought a new brake switch (I believe I found a post by JimLombardi with a link to a Rock Auto switch for ~$38 which I bought; thanks Jim!) and installed it a few minutes ago. Went for a short test drive around the neighborhood and had no “engine failsafe mode” warning, and my cruise worked for the first time in what seems like 6 months.

I’ll report back after a few trips to work and back on how things are working out.

Thanks for the help.

Mike

 

200 mile update:

Everything seems fine so far. Seems like the brake switch fixed my problems. I’ll post back if the issues persist.

Mike

 

Great! Who would expect that that set of symptoms would have the brake switch as a root cause?

 

your brake light switch has malfunctioned replace switch disconnect battery and reconnect battery they should definitely help with your issue

 

Well….he solved the problem 7+ years ago (2014) by doing exactly that: replacing the brake light switch.

I have also fallen into the trap of missing the last posting date of a thread - very easy to do.

 

I had similar issues with my 2007 XKR , cruise control not working so change the sensors on the wheels, this cleared the cruise control fault, also had the car sounding like it was misfiring running on 6 cylinders, if i accelerated the fault restricted engine performance came up but would clear itself after a while, car had a strong smell of petrol as the exhaust was smoking, ( i put this down to the fuel not being ignited).
changed the 8 engine coils and the car is now running sweet, no lumpy engine idling, acceleration is spot on, fuel consumption has improved no warning lights on the dash.
i bought the engine coils from Ashwood Motors
Ignition Coil Jaguar XK XKR 3.5 + 4.2 V8 (2006-09) - AJ810445 SKU: AJ810445-2 Price: £26.84 with the first order discount it came in at £203.98


Phone number for Ashwood Jaguar parts :- 01536 639069
Email Sales :- sales@ashwoodjagparts.co.uk
Email :- Ashwood Jag Parts https://www.ashwoodjagparts.co.uk/

 

I had similar issues with my 2007 XKR , cruise control not working so change the sensors on the wheels, this cleared the cruise control fault, also had the car sounding like it was misfiring running on 6 cylinders, if i accelerated the fault restricted engine performance came up but would clear itself after a while, car had a strong smell of petrol as the exhaust was smoking, ( i put this down to the fuel not being ignited).
changed the 8 engine coils and the car is now running sweet, no lumpy engine idling, acceleration is spot on, fuel consumption has improved no warning lights on the dash.
i bought the engine coils from Ashwood Motors
Ignition Coil Jaguar XK XKR 3.5 + 4.2 V8 (2006-09) - AJ810445 SKU: AJ810445-2 Price: £26.84 with the first order discount it came in at £203.98


Phone number for Ashwood Jaguar parts :- 01536 639069
Email Sales :- sales@ashwoodjagparts.co.uk
Email :- Ashwood Jag Parts https://www.ashwoodjagparts.co.uk/