The car starts & runs OK. I can hear the ABS pump running. If I drive off without touching the brakes the ABS light goes out. However if I touch the brake pedal even very lightly then I get a beep & then ABS FAULT appears on the dash closely followed by TRACTION FAILURE. Another important data point is that the brake lights don't work. Nanocom finds no faults in ABS (WABCO D) or gearbox.

Googling I found a couple of threads where a new brake switch fixed the problem so I just ordered a replacement for delivery on Tuesday for €15.99 delivered from Amazon. It's not genuine but a genuine LR part costs €50 & I can't get delivery until after Xmas.

Here is someone with the same problem. https://www.landyzone.co.uk/land-rover/p38-brake-light-switch-abs-fault-traction-failure.200305/

Anyone care to speculate why a duff brake switch would throw the ABS FAULT & TRACTION FAILURE? If anyone sees these messages it's definitely worth checking whether the brake lights are working. I realise now that I was driving about all day yesterday without brake lights.

The brake light switch is connected to the ABS system and the BECM. As soon as you press the brake pedal, even lightly, pressure will be injected into the braking system and if the brake switch is not operating I assume the system will think the brakes have not been applied and therefore flag a fault and the ABS & Traction lamps will illuminate - The ABS system flags the fault but the BECM controls the lamps and the messages on the dash.

In further research I have dug up various threads in various forums including this one where the ABS FAULT & TRACTION FAILURE precipitated by a light dab on the brake pedal is fixed with a new brake light switch. Importantly that error message indicates that the switch has failed & that the brake lights are not working so needs fixing ASAP.

Please can someone point me to the section of RAVE that covers replacement of the brake switch? I have been searching but cannot find any detail.

Chapter 70, Brakes - Repair - Stop Light Switch From 99MY.

It has a sort of bayonet fixing so just needs twisting out and the new one pushing in and twisting (although you do have to wrestle one of the heater ducts out of the way to get to it).

Gilbertd wrote:

Chapter 70, Brakes - Repair - Stop Light Switch From 99MY.

It has a sort of bayonet fixing so just needs twisting out and the new one pushing in and twisting (although you do have to wrestle one of the heater ducts out of the way to get to it).

Aha! When I looked through RAVE I searched on 'Brake light switch' which drew a blank. I have now found the correct section:-

STOP LIGHT SWITCH - FROM 99MY
Service repair no - 70.35.42

Remove closing panel from fascia. See
CHASSIS AND BODY, Repair.
Remove screw and remove heater outlet duct.
Remove 4 scrivets and remove access panel
from fascia.
Release and remove heater air duct for access
to stop light switch.
Refit

Ensure new stop light switch plunger is fully
extended for initial setting.
Fit stop light switch to pedal bracket and connect
multiplug.
Fit heater air duct.
Fit access panel and secure with scrivets.
Fit heater outlet duct and secure with screw.
Fit closing panel to fascia. See CHASSIS AND
BODY, Repair.

It's fixed. The €15 stop light switch was not a genuine LR part but was embossed with the LR part number XKB100170. It's a bit of a fiddle lying upside down under the steering wheel to fit but it is really only a ten minute job.

It's a pity that the BECM doesn't indicate a failed stop light switch with a more useful error message than ABS FAULT & TRACTION FAILUREthe

I checked with my Nanocom & in the Inputs for WABCO D it has Brake Switch 1 & Brake Switch 2. The old failed switch showed both Closed & only Brake Switch 2 flips to Open when I put my foot on the brake. The new switch shows both Brake Switch 1 & 2 flip from Closed to Open when I put my foot on the brake.

Hilariously this is the fitting instructions on the Amazon web page.

Installation:
Reassemble the handbrake control switch of the car panel.
Depending on your make and model you may need to remove the door panel to access the switch wiring.
Install a new parking brake control switch in the door panel.
Reconnect the parking brake control switch.Test the operation of the window and switch before installing the door panel.
Reinstall the door panel and power it.

I'm glad you got it sorted despite Amazon's very helpful instructions!

A couple of days ago just before I set off from dance to the UK the same damn error message appeared again. This time ABS FAULT & TRACTION FAILURE appeared without any touch on the brake pedal. I thought that a wheel sensor might have failed but of course as I had just recently replaced the brake switch I was suspicious this could be the cause of the problem.

When I put the Nanocom on it actually displayed a Fault that the brake switch had failed. It also showed both brake switches closed Closed & only Brake Switch 1 flipped to Open when I put my foot on the brake.

I didn't have a spare brake switch or time to wait for one to be delivered before I headed back to the UK. The brake lights were working & there wasn't obviously anything wrong with performance of the brakes so I risked driving the 250 miles. I ordered a switch for delivery in the UK so it was waiting for me when we returned.

Today I fitted the new brake switch which was working OK according to the Nanocom wee between each wheel up to 5mph. Both brake light switches were flipping from Closed to Open when the brake pedal was pressed. The voltage at all the wheel sensors was the same (2.7V I think) & I could see the wheel speeds were comparable up to 5mph. The problem was I still had a beep followed by ABS FAULT then TRACTION FAILURE appearing on the message centre. I took the car for a short drive stopping & switching off the engine then restarting several times. Finally after about 5 or 6 times restarting the engine there are now no errors appearing & I can book it in for an MOT.

I don't understand why the ABS FAULT & TRACTION FAILURE messages still kept appearing even after the problem was corrected & faults cleared. It's just another quirk of the P38 I suppose.😀