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06 LR3 HDC/Transmission Fault?
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Member Since: 21 Feb 2024
Location: Kentucky
Posts: 1

United States 
06 LR3 HDC/Transmission Fault?

I haven't been able to drive my LR3 for the last 2 weeks due to an HDC/ Transmission fault that slowly became increasingly worse as time went on. Now, I can't leave the driveway. Basically what happens is I can start the vehicle and there will be no fault for as long as I sit and idle. After tapping the brake pedal several times (not exactly on the first tap, more like the 12th or 13th/sometimes less) I get the HDC and Transmission fault. Turn the vehicle off, clear the codes with the GAP tool and it does it again. What's strange is the other night it did fine and didn't trigger till about 2 miles in, but that was very very odd and never happens. I thought I was g2g and boom... it popped up.

Things I have tried.... New battery, passenger side red wire splice (fine), new oem brake light switch, unplugged the brake light housings (to rule out bulbs), cleaned all connections on DRIVER side footwell as some were corroded (had a sun roof drains leak but is now fixed), checked grounds, calibrated steering wheel sensor, checked TCM behind the battery, removed center console and checked all connections (all was good).

I also noticed that once I get the HDC/transmission fault that I can move the shifter even though my foot is not on the brake, but once fault is cleared it only shifts when my foot pressing the brake. As I said, it only throws these faults when after tapping on the brake several times, will run for an hour straight with no fault till the brake is tapped/pressed a few times.

Below is a copy and paste of the codes I get on the GAP tool once u get the fault.....

[Engine Petrol]

P0504-64- Brake switch A/B correlation
Algorithm based failure - signal plausibility
failure (2A)

P0504-29 - Brake switch A/B correlation
General signal failure - signal is invalid (2A)

[Vehicle Dynamic]

C1A96-62- Brake lamp switch circuit-
Algorithm based failure - signal compare
failure (OB)


U0416-86 - Invalid data received from vehicle
dynamics control module- Bus signal/
message failure - signal is invalid (2B)
Post #236257621st Feb 2024 3:44 am
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Member Since: 23 Mar 2018
Location: Norfolk uk
Posts: 96

England 2010 Discovery 4 3.0 TDV6 GS Auto Stornoway GreyDiscovery 4

try swapping the brake light bulbs for some new decent ones, the filaments maybe breaking down. Also make sure the battery is good.
Post #236258521st Feb 2024 9:48 am
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Pete K

Member Since: 15 Jan 2016
Location: GL
Posts: 10415

England 2005 Discovery 3 TDV6 HSE Auto Rimini RedDiscovery 3

I’d be trying another brake switch. Make sure it is adjusted correctly. There is a procedure for fitting on YouTube.
Post #236258921st Feb 2024 10:41 am
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Member Since: 01 Feb 2024
Location: Beckenham
Posts: 15


You already switched the brake switch and bulb, right? Did you check for a faulty brake lamp relay? 
Post #236260421st Feb 2024 1:27 pm
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