Discovery 300 ABS problem - please help

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yellowmitch

New Member
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19
Hi there. My Discovery ABS Light stays on.

When I had it connected up at the dealers it says that the pump power stays on after vehicle stopped (or something like that)

Do I need a new pump or what is the most likely problem?

Could it be a fuse or a relay or something?

Alan
 
Mine's the same, took mine to an ABS specialist who told me that all I had to do was hammer the sensor withe a blunt instrument back into place! Did not try it myself, but did watch him do what he said. I have however, found some info on the web that gives you the info on which component is causing the problem. Easy to do but not had time myself to try it. Here is the info, also covers Range Rover, if after you have read this and your still unsure, please, please, please do not try it, get some expert advice.

ABS Diagnostics

But there's an easy DIY way to read and reset these diagnostic codes. And you don't need a testbook computer - all you need is a bit of wire, or a paperclip!

There is nothing new in this document. All I have done is gathered together various other Internet documents, and added some notes on where the various connectors are on my Discovery. Many of the internet document relate to US-spec vehicles, where the components are located elsewhere.

My Disco is a UK-spec 1995 300 TDi XS.

The ABS ECU itself is a standard Bosch/Wabco part. If you do some googling, you'll find that the same techniques and codes apply to many other vehicles that use this unit.

First of all, we need to find the ABS warning light relay. On mine, it's in the passenger footwell, under the glove compartment. Lever out the 3 press-in studs, and the trim panel can drop. There are half a dozen relays in there. The one we're looking for is (on mine!) nearest to you, but in the second row, "behind" some others. Difficult to explain, but obvious when you get in there. The relay bases slide onto brackets, push them about an inch "away from the wires" and they'll come free.

The one we're looking for has a green base, and has 2 black wires, 1 black/green wire and 1 brown/red wire.

Disconnect this relay - pull it out of the socket.

Now we need to find the ABS diagnostic connector. This is where I struggled. All of the internet info says it's a blue connector under a seat, but that's just on US-spec vehicles. Rave says it's a 5-pin connector near the fuse box. But I couldn’t find that either. I believe that earlier (pre-95) models used this, but later ones moved it to the main diagnostic connector. This is a 16-pin socket, located under the steering wheel, just above the clutch. You don't need to remove any trim panels to get to it - although you may want to pop out the panel it's mounted on - it's not immediately clear how the pins are numbered, so look at the colours of the wires.

The 2 pins we're interested in are pin4 (black) - ground, and pin15 (red/green) which goes to the ABS unit. If the internet sources are to be believed, the abs diagnostic wire may be black/pink on some models, and on the 5-pin connector we're interested in pins 2 and 5. But this has not been verified.

You need some way of bridging the 2 pins. A paper clip or a piece of solid-core wire is ideal.

Now, we're ready to go.

Make sure the relay is disconnected. Turn on the ignition. The ABS warning light should come on, as usual.

Bridge the 2 pins on the diagnostic connector.

After 5 seconds, the ABS warning light should go out. It will then flash a pattern. From this, we can obtain the 2-digit fault code.

first of all there will be 2 slow flashes - one longer than the other, with a gap of about 2 seconds.

Then the interesting bit. The lamp will then flash, at about one flash per second. Count these flashes - that's your first digit.

Then a pause

Then it will flash out the second digit.

This sequence will then repeat indefinitely (start, digit 1, digit 2).

If you disconnect the link when the lights are flashing, it will clear the fault. Reconnecting it will show the next stored fault. If you have patience, you can read out and clear the entire contents of the ABS memory.

In my case, all of the stored fault codes were the same - 2 flashes, then 12 flashes. So you look up 2-12 in the table below, and find "air gap, right hand front wheel speed sensor." This ties in with my own experience - I know that re-seating that sensor will temporarily cure my fault!

Hope that someone finds this information useful.

Bruce.



The following table was obtained from

http://www.bba-reman.com/content.asp...identification

I copied this from Bruce's previous post. Hope he doesn't mind. It worked for me. I was surprised that it did but it did.

Matt
 
Thanks for this. I will try it :)

Here is some more info in the meantime

Hi there.

My disco is a December 1995 (96 model year) 300 series ES V8i which I have since retrofitted (NO WIRES CUT!!!) with a 300Tdi from a 1995 GS vehicle.

So now it's a 1996 ES Tdi :)

The error on the diagnostic machine says "pump running when not switched on"

I have tried swopping some of the under dash relays and the wabco ecu with ones from another scrapper disco but it has made no difference.

I have also tried putting power to the pump out under the bonnet and it kicks into life so I presume it works ok.

If I disconnect things, like the pump or ecu, leave it a while and then plug them back in, the fault clears and the vehicle drives correctly.

The instant that I stop and restart the engine though the light is back on :(

What is wrong?

Please help. Only one week until my MOT and I need the car !!!
 
Thanks for the info, worked a treat, my relay was under passenger dash panel as well, but 2nd row second relay towards front, differant coloured wires as well. Had fixed LFsensor but light still was not going out, rechecked using above info, found heaps of codes as had all sensors unplugged, but one kept coming up, RF sensor. So checked and of course had missed plugging that one back in!!!! Reconnect and away. Thanks again.
 
I copied this from Bruce's previous post. Hope he doesn't mind. It worked for me. I was surprised that it did but it did.

Matt

A big thank you to both Bruce and Matt. This worked a treat on my 98 Jap re imported Disco that now lives in Ireland. I cleared the codes and used the "Blunt instrument" approach. The wiring colors were slightly different and I can verify that the Jap version has a Black\Pink ABS diagnostic wire.

Thanks again

Wildrover
 
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