ABS Diagnosing....

[davek0974]

Hi all, before anyone says it, yes i did search but i'm seeing conflicting info so i thought it safets to ask before frying my ABS ECU

I have never had the ABS lamp on my dash alight so i'm guessing the bulb has been removed befor i bought the motor 3 months ago.

To save ripping the dash out i am going to lash up a spare small bulb to the ABS lamp relay base at the point where the wire to the dash comes from, its a black/grey wire acording to the autodata diagram from pin 30 on the relay.

The main problem is triggering the blink codes, i dont yet know if i have the 15pin obd socket or the blue 5 pin abs diag socket. Either way, i am being told to remove a relay first BUT one post says remove the SYSTEM relay, another says remove the LAMP relay???

If its the blue connector, i need the black and black/pink wires.

I am hoping that the lamp will light when i connect it up or there is a bigger problem. I have checked all fuses etc first.

So is there a proven CORRECT method of getting it to blink???

Just to muddy the waters more, i have this tidy page that does not mention removing ANY relay at all????

My link

Any help anyone????

DAve

[Range Rover Blues]

Err, what year is the car? I know RRC far better than Disco but I recall something about the system changing on later models.

The Disco I have worked on where ealrier 300s very similar to the RRC and the blue relay/blue socket was the lamp relay IIRC so that it will flash properly.

Strictly speaking if the ABS light never comes on at startup it shouldn't pass an MOT. I had one car some nutter had wired the ABS light to the ignition light to get an MOT rather than re-seat the front sensors and get the brakes working properly.

Have you consulted RAVE, if so did it shed any light?

[davek0974]

Err, what year is the car? I know RRC far better than Disco but I recall something about the system changing on later models.

The Disco I have worked on where ealrier 300s very similar to the RRC and the blue relay/blue socket was the lamp relay IIRC so that it will flash properly.

Strictly speaking if the ABS light never comes on at startup it shouldn't pass an MOT. I had one car some nutter had wired the ABS light to the ignition light to get an MOT rather than re-seat the front sensors and get the brakes working properly.

Have you consulted RAVE, if so did it shed any light?

Sorry, its a late 1994 D1 300tdi ES manual.

Not checked RAVE yet, will do tonight.

Dave

[Range Rover Blues]

Then it's the same age as my LSE. I know the plug is under the dash rather than the seat on the Disco but I'd be looking for a sqaure 4-pin blue plug without a connector on it IIRC. " diagonally opposite wires have black or mainly black insulation and these are shorted together to start the blink sequence (it keep cycling the same code which is cleared when you remove the short). A paper clip is ideal for this.

Try this

[davek0974]

Yes i have seen that page/s before, i thinks its the one where one setion says pull the lamp relay and another does not,

Do i need to pull a rely or not???

Does anyone know what the other pin in the 4 pole plug does???

Dave

[davek0974]

Ok, the temporary lamp idea worked, that confirms that the system is working and that the dash bulb is either missing or broken.

The codes i read were as follows, in the order of reading,

2-2

2-7

2-12

2-14

2-15

4-15

5-15

6-13

All clear.

Now, where do i start???

Dave

[karlo]

[davek0974]

Thanks Karlo, there are a few codes missing, 2-2 for instance - pump relay fault

I'm guessing that the next thing i need to do is drive it and re-test for current codes??

[Range Rover Blues]

The system spits out codes in reverse order, the first one is your most recent fault.

yes drive it and check it again in a few days but if you get more than 1 code then you now know the in what order they occured.

For example you might get a developing fault in a wheel senor that leads to more than 1 fault code.

[davek0974]

Ok, thanks, that makes sense. So a failing sensor might show a large air gap then a poor signal then no signal etc.

Dave

[davek0974]

Ok, driven and re-read the blink codes,

To my amazement there was only ONE code - 6-13 which i think is left rear signal weak or missing.

But is that left looking from drivers seat or front of vehicle????

It would be better if they used near-side or off-side

Dave

[fozsug]

Ok, driven and re-read the blink codes,

To my amazement there was only ONE code - 6-13 which i think is left rear signal weak or missing.

But is that left looking from drivers seat or front of vehicle????

It would be better if they used near-side or off-side

Dave

Passenger side rear

[davek0974]

Ok, while i'm waiting for some lamps to come, i thought i'd search for more info.

Looking at the Wabco manual for the ABS system, they show a blink-switch, landrover did not fit this.

The Wabco wiring diagram shows that this switch does just two functions when switched on - 1, It disconnects the diagnostics port and 2, It shorts the same wire to ground as the paperclip method does.

Now, reading the manual, it states to turn ignition on then flip the blink-switch. It does not say remove any relays etc.

What difference does the relay being there make or not??????

The Wabco manual is an excellent bit of stuff to have.

Dave

[Range Rover Blues]

I think the relay is something to do with the lamp. I might have inadvertantly done a blink test without removing it but I can't swear to it or what the result was. Possibly it allows the ECU to keep blinking the code until you are ready to clear it.

As for the LHS/nearside thing. How would it work on a LHD? automotice systems are designed for workwide use and conventions are used so that everyone agrees )hopefully)

LHS/RHS are always as viewed from the driver's seat. Sometimes the part number will reflect the handedness of a component and as you have found diagnostics describe which side the sensor is located on.

Weak signal can be a wheel bearing but I remember asomething about LR selling a replacement part for the sensor that includes a new section of wiring loom back to the ECU. If you keep having problems you might want to check that.

[davek0974]

I think the relay is something to do with the lamp. I might have inadvertantly done a blink test without removing it but I can't swear to it or what the result was. Possibly it allows the ECU to keep blinking the code until you are ready to clear it.

As for the LHS/nearside thing. How would it work on a LHD? automotice systems are designed for workwide use and conventions are used so that everyone agrees )hopefully)

LHS/RHS are always as viewed from the driver's seat. Sometimes the part number will reflect the handedness of a component and as you have found diagnostics describe which side the sensor is located on.

Weak signal can be a wheel bearing but I remember asomething about LR selling a replacement part for the sensor that includes a new section of wiring loom back to the ECU. If you keep having problems you might want to check that.

Interesting, i'll check out the relay/no relay thing when its going again.

I managed to push the suspect sensor in about 3mm so hopefully thats all it is. I cant test it yet because i've got the track-rod in bits and the rear anti-roll bar off

Of course, i wasnt thinking of the export market

Dave