2006 LR3 P0504 and C1A96

rangerover

Member
Jan 14, 2019
5
0
NY
I'm having a difficult time troubleshooting this code on my rover. It started out as something that would happen intermittently and restarting the truck was good enough to fix it. It got a little worse, so I replaced the brake light switch, and lights which gave me about another week before the same error code would come back. Now, the code is permanently on unless I'm on the brake

With the car OFF, brake depressed, the two circuits (Brake Lamp Switch and Brake Switch) both show "active". When I release the pedal, the Brake-lamp-switch returns to an "inactive' state and the brake-switch remains active. This causes the fault. At the same time, the shift-interlock clicks once to release when the brake is depressed but does not re-lock when, in park, and foot off the brake. I can shift freely without using the brake (again, because he circuit is "active").

all brake lights are fully functional and the issue does not go away when I remove the brake lights or change the bulbs. Reverse lights are functional as well. I've also tried swapping brake switches back and the issue remains. Something is up with the other circuit causing the ABS module to get a stuck "high" signal.

No fuse (ie f66) is blown.

I've found other reports of this which lead to a corroded or broken "red" wire but I'm not finding any of that. I'm also not seeing the link to be based on pictures and diagrams from others. I've scanned from the passenger side B-piller up into the kicker panel so far, along with a little behind the battery. Nothing appears broken, nothing is obviously rusted.

Could this be anything else?




Ref:
foot-off-pedal.jpg
pass-side-kicker1.jpg

pass-side-kicker2.jpg
 

discostew

Well-known member
Sep 14, 2010
6,373
477
Northern Illinois
The real description of your P0504 code is actually Brake switch corrolation fault. The ABS fault C1A96 says that the brake light switch is open. There should be 2 power feeds to that brake light switch. One operates the brake lights, the other tells the abs system that you are on the brake pedal. You could also have the brake switch in and not propperly adjusted.
 

rangerover

Member
Jan 14, 2019
5
0
NY
To close the loop, the red wire that feeds the brake switch is broken/corroded between the switch connector and fuse box.

I needed the truck back on the road so I jumped the circuit at the switch and am back in action. I'll hunt down the rest of the wire once I have more time.
 

lordhelemt

Well-known member
Dec 18, 2010
70
4
I had a similar issue. Mine was corroded at the connector. I think I have pics somewhere but am currently traveling so I’ll need a few days to find them.

I was able to source new connectors and bought a few extra to satisfy the minimum order. I’ll see if I have any left. I’ll check when I get back to town later this week
 

lordhelemt

Well-known member
Dec 18, 2010
70
4
Actually here’s the thread