300 abs light on.

Since found you do not need to replace relay to clear fault. Just wait for code to finish and restart before turning off ignition or re inserting link. Replacing relay meant I had to walk around the car which allowed the sequence to complete!

Hi,

I had a similar problem on my Discovery 300 TDI My local garage were unable to diagnose the fault save for sll the usual checks which proved inconclusive. Eventually, I took it to Land Rover, who diagnosed a faulty switch under the brake pedal. The worrying thing was that although I still had a braking system, albeit with no ABS, the brake lights were not working as the pedal did not register that it had been pressed.

The cost of the switch was £35.

Kind regards

I'd also like to add my thanks for this information.

I had a fuse blow that fed the brake lights, and the ABS light was stuck on afterwards.

I followed the relay and paper clip procedure showed the fault was the brake peddle switch. Now the code is clear and the ABS light is off.

Thanks guys!!!!

I`ve had my disco a week now, love it to bits! However i have a similar problem, i can drive the car 1 day and the abs light works perfectly then the next it`ll just come on when i`m turning right it then stays on. if i pull over and turn the engine off then restart and drive off it will act as it should most of the time! Any ideas?? it seams to just do it when ever it feels and always on right handers :doh:
cheers for any help, Karl

you got to bite the bullet and do the diagnostic thing mate!

passenger footwell or where ever else,dependent on model,relays,bits of wire,counting flashes....its all on here somewhere...and I've used it- it works !!!

as a starter,sounds like theres a fault on one of the front ABS setups :bolt:

:welcome:

Had that n/s front. Sensor was out of true owing to loose bearing. Wheel not running straight so sensor not picking up properly.

Had a similar problem with 1998 disco 1, with light staying on.
The job below should take about an hour if you know what you are doing it took me about 12 hours.
did the link diag got 2-12 flashes- front right sensor checked sensor with multimeter, open circuit. Changed sensor drove upto 5mph abs light goes out "yippee"
Put car in reverse backed up braked, abs light on continuously again.
Diag link now gives 2-3 and 4-12.
The light dims slighty for a split second when ignition first turned on so changed warning relay green relay green base on passenger side no difference.
Remove relay, abs light stays on. wire a bulb accross relay terminals that comes on and then goes out when ignition turned on but abs light still on.
Help please final day for the MOT retest tommorrow.
Cheers.
Paul.

OK - first code 2-3 is (from wabco manual) -

Recirculation pump does
not operate (pump does
not switch on).

Recommended action (again from wabco):

Check the recirculation
pump wiring, the pump
relay and fuse and pump
connections. Repair or
replace as required.

I would check the wiring first - clean the connectors and also check the earth (mine was broken off). Also - for some reason mine used to report this fault intermittently until I cleaned the contacts on the RH headlight which had stopped working. I think they share the same earth!


4-12 Right front wheel speed
sensor open circuit.

Since this is the one you replaced then I suggest you check the wiring to it.

Hate to say this but a 2-12 usually indicates air gap is too big so you might have been able to cure this by simply tapping it down a bit - worked for me and others on this and other threads.

Make sure that you clear all the faults down - remove shorting pin and wait for the sequence to complete before replacing. The 4-12 and other sensor faults only occur once you've actually used the brakes as the computer can't test them at start up (no wheel rotation).

Good luck.

Hi Stuart
Thanks for that info.
Not sure if I am clearing the memory I seem to have tried every combination,
The last time I tried I waited until the 2-3 flash finished then removed the link waited until abs light stayed on then re-inserted the link then after the 4 -12 flashes removed link then waited for the light to stay on then turn off ignition.
But if I then turn on ignition and reinsert the 3-2 and 4-12 codes are still there would not clearing the memory cause the light to stay on?
Cheers.
Paul.

Either your not clearing the faults - but the procedure you describe sounds OK - or they are re-occurring during start up.

The motor is certainly tested during the start up sequence. If you clear the fault and turn on the ignition with your foot on the brake then you can feel it.

Also, you can test the motor by shorting the relay - it's the big black one.

I'm not sure if the 4:12 is tested on start up but since it indicates open circuit and the computer is obviously able to measure the resistance of the sensor it would certainly be able to tell that it was not connected during its start up test.

Hi
I am getting there, to make sure of my technique I disconnected the lsf sensor then got a 4-14 error which did clear when reconnected.
The sensors must be tested for resistance on startup. the OSFr tests ok on a multimeter about 1k resistance.
I will try swapping the left and right sensors and see what happens. (obviously wont drive in this condition)
I will investigate the pump when I suss the simpler of the 2 faults.
Thanks again.
Paul.

Just swapped the sensors wiring over by making up extension leads.

But the fault still shows up as the front right so the fault must be in the wiring (although the left and right input resistances read the same) or the ABS ecu.
Is it possible to do a hard reset or similar on the ABS ecu?
Cheers.
Paul.

Certainly sounds like a wiring fault to me - no idea if you can do a hard reset.

However, if you take out the abs computer you should be able to measure the resistance at that end. My guess is you'll find it infinite (open circuit) as you have a broken wire or loose connection. The pin numbers are in the wabco manual - do you have it?

I know these computers rarely fail but got a second hand one swapped it over connected up the link cleared all the stored faults in the replacement turn ignition off back on working spot on now.
Thanks for your help.
Cheers.
paul.

thebiglad said:

How can you spin the wheel on a permanent 4 wheel drive? Am I missing something?

Click to expand...

just make sure it's out of gear lol

Noticed that the link does't work, so here are the codes.

LANDROVER FAULT CODES

Fault Code

Fault location

1-1

At start of sequence

2-6

(BPP)Brake pedal position switch

2-7

In system relay, when ignition is off the ECU supply is continuous.

2-8

In system relay, there is no solenoid valve supply.

2-12

Is an air gap, right hand front wheel speed sensor.

2-13

Is an air gap, left hand rear wheel speed sensor.

2-14

Is an air gap, left hand front wheel speed sensor.

2-15

Is an air gap, right hand rear wheel speed sensor

3-0

The ECU connection/wiring to right hand front inlet, hydraulic modulator solenoid valve.

3-1

The ECU connection or wiring to right hand front outlet, hydraulic modulator solenoid valve.

3-2

The ECU connection or wiring to left hand front inlet, hydraulic modulator solenoid valve.

3-3

The ECU connection or wiring to left hand front outlet, hydraulic modulator solenoid valve.

3-4

The ECU connection or wiring to right hand rear inlet, hydraulic modulator solenoid valve.

3-5

The ECU connection or wiring to right hand rear outlet, hydraulic modulator solenoid valve.

3-6

The ECU connection or wiring to left hand rear inlet, hydraulic modulator solenoid valve.

3-7

The ECU connection or wiring to left hand rear outlet, hydraulic modulator solenoid valve.

3-8

The ECU connection or wiring to inlet, isolating, hydraulic modulator solenoid valve.

3-9

The ECU connection or wiring to outlet, isolating, hydraulic modulator solenoid valve.

4-0

The ECU connection or short circuit to right hand front inlet, hydraulic modulator solenoid valve.(HMSV)

4-1

The ECU connection or short circuit to right hand front outlet, HMSV.

4-2

The ECU connection or short circuit to left hand front inlet, HMSV.

4-3

The ECU connection or short circuit to left hand front outlet, HMSV.

4-4

The ECU connection or short circuit to right hand rear inlet, HMSV.

4-5

The ECU connection or short circuit to right hand rear outlet, HMSV.

4-6

The ECU connection or short circuit to left hand rear inlet, HMSV.

4-7

The ECU connection or short circuit to left hand rear outlet, HMSV.

4-8

The ECU connection or short circuit to inlet, isolating, HMSV.

4-9

The ECU connection or short circuit to outlet, isolating, HMSV.

5-0

The ECU or solenoid valve supply short circuit to right hand front inlet, HMSV.

5-1

The ECU or solenoid valve supply short circuit to right hand front outlet, HMSV.

5-2

The ECU or solenoid valve supply short circuit to left hand front inlet, HMSV.

5-3

The ECU or solenoid valve supply short circuit to left hand front outlet, HMSV.

5-4

The ECU or solenoid valve supply short circuit to right hand rear inlet, HMSV.

5-5

The ECU or solenoid valve supply short circuit to right hand rear outlet, HMSV.

5-6

The ECU or solenoid valve supply short circuit to left hand rear inlet, HMSV.

5-7

The ECU or solenoid valve supply short circuit to left hand rear outlet, HMSV.

5-8

The ECU or solenoid valve supply short circuit to inlet, isolating, HMSV.

5-9

The ECU or solenoid valve supply short circuit to outlet, isolating, HMSV.

5-12

Sensor or wiring on right hand front wheel speed sensor.

5-13

Sensor or wiring on left hand rear wheel speed sensor.

5-14

Sensor or wiring on left hand front wheel speed sensor.

5-15

Sensor or wiring on right hand rear wheel speed sensor.

6-0

Short circuit of two ECU or solenoid connections to right hand front inlet, HMSV.

6-1

Short circuit of two ECU/ solenoid connections to right hand front outlet, HMSV.

6-2

Short circuit of two ECU or solenoid connections to left hand front inlet, HMSV.

6-3

Short circuit of two ECU or solenoid connections to left hand front outlet, HMSV.

6-4

Short circuit of two ECU or solenoid connections to right hand rear inlet, HMSV.

6-5

Short circuit of two ECU or solenoid connections to right hand rear outlet, H MSV.

6-6

Short circuit of two ECU or solenoid connections to left hand rear inlet, HMSV.

6-7

Short circuit of two ECU or solenoid connections to left hand rear outlet, HMSV.

6-8

Short circuit of two ECU or solenoid connections to inlet, isolating, HMSV.

6-9

Short circuit of two ECU or solenoid connections to outlet, isolating, HMSV.

6-12

Is no output or an air gap with right hand front wheel speed sensor.

6-13

Is no output or a large air gap with left hand rear wheel speed sensor.

6-14

Is no output or a large air gap with left hand front wheel speed sensor.

6-15

Is no output or a large air gap with right hand rear wheel speed sensor.

This is an incomplete list of codes.
Wabco seem to have moved their manuals to here - http://www.meritorwabco.com/(S(i4ig...?product_1_id=2&product_id=17&product_level=2
And the type C used on my 95 disco is described here - http://www.meritorwabco.com/MeritorWABCO_document/mm38.pdf

This is just a short note of thanks to everyone who has contributed to this thread. I've a '96 300TDI ES that's had an issue with the ABS on and off (literally!!) for the last 4 or 5 months. Having paid to have the system read & reset umpteen times (as well as fitting two new wheel speed sensors to the same wheel) I finally found this thread last night. Having tonight spent an hour following the instructions (the blink code was 2:6, brake light switch feed) I now have fully functioning ABS again.

Just a couple of notes from my reset: whilst the wiring colours on the 16 way ABS diagnostic connector were as the description the relay wires weren't. It was also complicated by the fact that there were two green relays of which neither had the right wiring colours. In the end I plumped for the green one with two black wires (which was at the back of the relay stack and not the front where the other green one was). Also, when reading / resetting the codes the engine management light was sometimes also going on/off. Whether I got it right or wrong the codes played, reset and the bolted up car works fine.

Once again, many thanks!!!:tea::tea::tea:

Just an update on the above. Whilst the car worked fine for many weeks after the above I started to get the light coming back on again periodically. Each time when I read the code it was the same 2:6 code (brake light switch feed). However the (new) brake light switch seemed to be working fine. The periods between the resets and the abs light coming on again kept getting shorter and shorter whilst the switch still seemed fine.

Confusing.

Several months later the SRS light came on in sympathy with the ABS light, with the SRS light due to a faulty rotary coupling (when the SRS light came on I also found that the horn had gone AWOL). Whilst switching the rotary coupling fixed the SRS light and the horn it also - after once again resetting the ABS ECU with my trusty paperclip - appears to have fixed the ABS light (which is once again working normally). The car is a '96 300TDI auto ES (with cruise). In knowing that there are two switches on the brake pedal on this model is there a circuit link anywhere that would cause the ABS ECU to trip due to a track failure in the rotary coupling?