2005 LR3 code P0504 brake switch

[Stormbringer]

Hello guys. First post. My 05 LR3 is giving me this code. I started having issues about every other start up with HDC not working, suspension failure and yellow brake light. This could be remedied with a second start up of the vehicle. The errors now stay away with a quick restart of the vehicle but will usually show up if not driven for several hours. I did some research and have checked the following.

The brake light switch seemed fine but I went ahead and replaced it. My rear tail lights and brake lights work properly and seem fine. I have not replaced the bulbs.

I have charged the old battery 09/11 and it tests out fine as well as the alternator and voltage regulator. I did buy a new battery.

I have checked the ground wires and they look ok.

Suggestions?

 

[Houm_WA]

Hmmm....you hit the biggies. Steering angle sensor perhaps? Do you own a GAP tool?

 

[Stormbringer]

Hmmm....you hit the biggies. Steering angle sensor perhaps? Do you own a GAP tool?

No Gap tool. Very strange to me that the problem will go away with a second startup and then come back the next day.

Mike. May just have to take down to the dealer.

 

[Houm_WA]

Could be a soft fault. You should get an IIDTool for sure.

 

[douglastic]

Maybe replace the rear bulbs anyway

Could be some minor issue you can't see - slight corrosion, contact, separation, etc

And they're cheap enough

 

[bbyer]

Maybe replace the rear bulbs anyway

Could be some minor issue you can't see - slight corrosion, contact, separation, etc

And they're cheap enough

I would agree, and purchase the bulbs from your Land Rover dealer as you must try to get your 3 back to factory spec.

Also remove the two backup light bulbs temporarily as they in the extreme, can affect the ABS which is what your problem probably is - well the ABS/Anti Skid is OK, but something is affecting signal to the ABS and that is why you get the DownHill Decent light.

My view is that the solution is simple but finding it is near impossible - mostly trial and error. The dealer will not be able to do much more than you can except charge you for the effort. It is not that dealers are bad, it is just that these problems can be tricky and are for the most part, cut and try.

Within the link below, you will find a number of jpg's and pdf's related to the braking system wiring. If you study them for a few days, you will see how all is interconnected and why those on the Board here usually suggest all new factory bulbs at the rear, (including signal light bulbs). The cost is small and it is a good start to the trouble shooting - eliminating potential problems, or with luck, resolving the problem.

I see most of the files re the link below have a thousand downloads and some near three thousand so it appears some think the information might be of value. One related to changing out the brake light switch which you have already done has near six thousand downloads so your problem is not unique.

https://www.disco3.co.uk/gallery/thumbnails.php?album=5082