Disco 3 electronics problem

Transmission limp home mode? D2 drops into 4th convertor drive if fault arises when driving, 3rd convertor drive if fault exists on start up. Very sluggish. Has something similar happened?

Chafed wiring. My D2 earthed itself against the gearbox casing: was worse when the contact area was wet.

Hi, all.

Disco 3, 2.7l TDV6 06 plate.

Driving at constant motorway speed, and:

BONG: HDC fault, HDC unavailable BONG: Transmission fault BONG: Suspension lowering.

Terrain response programs unavailable. Unable to raise suspension. Transmission does seen to function in auto, but feels sluggish.

Turning off vehicle and re-starting clears faults for half a mile or so. Then same sequence of bongs and faults.

Sent to independent garage, still there.

Googling suggests:

-Brake light bulbs ( yes, really! Aparently, if the filament in a dual-filament bulb fails in such a way that it can touch the other filament, this causes no end of mischief in the electronics! )

-Corroded wiring / connectors in wheel-arch areas;

-Battery.

Anything else?

Well, Independent LR garage put it on their autologic diagnostic doo-hicky and it's reporting the brake light switch producuing 'inconsistent output'.

Further testing by myself gives this result:

1) During driving, the fault in intermittent, but when it occours, it occours on releasing the brake pedal.

2) With the car powered-up, but without the engine running, the following is observed:

With the transmission in P, pressing and releasing the footbrake causes the interlock solenoid in the gear handle to go click-click as expected.

Repeatedly depressing the brake pedal: click-click. click-click. click-click. silence. Suddenly, the interlock solenoid is no longer operating. The transmission can be pulled into gear without applying the footbrake. BONG BONG BONG all reported faults present.

So I'm fairly confident in the diagnosis thet the brake switch is goosed. It must have multiple contacts, and they are not all jiving together.

The replacement will be fitted tomorrow or next day.

Well, Independent LR garage put it on their autologic diagnostic doo-hicky and it's reporting the brake light switch producuing 'inconsistent output'.

Further testing by myself gives this result:

1) During driving, the fault in intermittent, but when it occours, it occours on releasing the brake pedal.

2) With the car powered-up, but without the engine running, the following is observed:

With the transmission in P, pressing and releasing the footbrake causes the interlock solenoid in the gear handle to go click-click as expected.

Repeatedly depressing the brake pedal: click-click. click-click. click-click. silence. Suddenly, the interlock solenoid is no longer operating. The transmission can be pulled into gear without applying the footbrake. BONG BONG BONG all reported faults present.

So I'm fairly confident in the diagnosis thet the brake switch is goosed. It must have multiple contacts, and they are not all jiving together.

The replacement will be fitted tomorrow or next day.

On or around Thu, 6 Jan 2011 13:41:01 -0000, "Andy Cooke" enlightened us thusly:

it's not alone in that. failed brake light fuse in the disco II leads to spurious difflock light and bongs when you press the brake pedal, on a vehicle with no diff lock!