ABS fault with no fault codes

domlinson · Oct 8, 2022

Hi all,

I've got a 2000 P38 4.0 HSE Auto

I know that P38 ABS faults are incredibly well documented across various forums, however I had my P38 scanned with a Nanocom today (thanks @DanClarke) and there are 0 faults reported.

This is odd, because I have a persistent fault that says "ABS fault" on the dash, and the ABS light stays on permanently.

How can I have an ABS fault reported on the dash, but no stored faults?

Thanks,
Dom

Datatek · Oct 9, 2022

domlinson said:
Hi all,

I've got a 2000 P38 4.0 HSE Auto

I know that P38 ABS faults are incredibly well documented across various forums, however I had my P38 scanned with a Nanocom today (thanks @DanClarke) and there are 0 faults reported.

This is odd, because I have a persistent fault that says "ABS fault" on the dash, and the ABS light stays on permanently.

How can I have an ABS fault reported on the dash, but no stored faults?

Thanks,
Dom

Duff ECU perhaps or corroded connector at the ECU

domlinson · Oct 9, 2022

Datatek said:
Duff ECU perhaps or corroded connector at the ECU

Thank you, have checked the ECU multi connectors themselves (3 of them from memory) and they all appeared fine, as did the ECU pins.

I believe someone has mentioned elsewhere that there are connectors in the A pillar/passenger footwell that corrode too, so I should check those too...

And then take the plunge and get hold of a different (hopefully working) ECU!

Mark Piercy · Oct 9, 2022

I recently did my front wheel bearings and had put the sensor too close to the reluctor ring. I got phantom abs codes and the odd brake pedal faults but nothing permanent. Just pulling the sensor out a touch stopped it.
Have you done any work on the hubs?

Datatek · Oct 9, 2022

Mark Piercy said:
I recently did my front wheel bearings and had put the sensor too close to the reluctor ring. I got phantom abs codes and the odd brake pedal faults but nothing permanent. Just pulling the sensor out a touch stopped it.
Have you done any work on the hubs?

That's interesting, the fitting procedure in RAVE is to push the sensors in until they touch the reluctor ring, air pressure then pushes them back a tad. Maybe yours are too tight in the housing.

DanClarke · Oct 9, 2022

As all sensors are providing "spot-on" voltages back to the ECU 2.29/2.3v when the car is just sat there stationary that would suggest to me the sensors/wiring back to the ECU is all good.
ECU swap-out would be my next step TBH, just to eradicate it.
I bought a spare listed as a WABCO-"D" (It has a part number of 446-044-074-0 on it) because I think they are getting as rare as rocking horse manure on the spares market and are about £75 a pop.
I could be persuaded to let a swap take place (cake/beer payment) for purely diagnostic purposes you understand.

God knows what a new LR "stealer" one costs.

I am scared to look/ask.
It needs testing I guess to see if it is as good as the "fault-free" one already on my Rangie.

domlinson · Oct 9, 2022

DanClarke said:
As all sensors are providing "spot-on" voltages back to the ECU 2.29/2.3v when the car is just sat there stationary that would suggest to me the sensors/wiring back to the ECU is all good.
ECU swap-out would be my next step TBH, just to eradicate it.
I bought a spare listed as a WABCO-"D" (It has a part number of 446-044-074-0 on it) because I think they are getting as rare as rocking horse manure on the spares market and are about £75 a pop.
I could be persuaded to let a swap take place (cake/beer payment) for purely diagnostic purposes you understand.
God knows what a new LR "stealer" one costs. I am scared to look/ask.
It needs testing I guess to see if it is as good as the "fault-free" one already on my Rangie.

That's interesting, the the ones I can find on eBay to match mine (part number the same as yours) are all £100+ for tested units. Still not a bad deal considering it could get my abs back and working without faults on the dash.

DanClarke · Oct 9, 2022

domlinson said:
That's interesting, the the ones I can find on eBay to match mine (part number the same as yours) are all £100+ for tested units. Still not a bad deal considering it could get my abs back and working without faults on the dash.

A swap-out is a quick way of discounting it (the ECU) as the source of the current problem.
The common fault with this unit is something about "....short to another..." message in the error logs and Marty has found a "fix" for that and can rework the ECU, but you are not seeing that message at all.
Your options are limited unfortunately.

Mark Piercy · Oct 9, 2022

Datatek said:
That's interesting, the fitting procedure in RAVE is to push the sensors in until they touch the reluctor ring, air pressure then pushes them back a tad. Maybe yours are too tight in the housing.

They have been out before when the ball joints and seals were done but she's done a fair bit of dirty road driving and quit possibly a little too snug

They d'or the moment and when they don't I'll address the matter... That dog is asleep for the moment

Datatek · Oct 9, 2022

Mark Piercy said:
They have been out before when the ball joints and seals were done but she's done a fair bit of dirty road driving and quit possibly a little too snug
They d'or the moment and when they don't I'll address the matter... That dog is asleep for the moment

If it aint broke, don't fix it. Transits suffer with fuse box failure like the P38

Mark Piercy · Oct 9, 2022

Datatek said:
If it aint broke, don't fix it. Transits suffer with fuse box failure like the P38

Water ingress mostly?

Datatek · Oct 10, 2022

Mark Piercy said:
Water ingress mostly?

Yes, more clever design. The heater intake plenum only has a drain at one end, my parking slopes a bit so the plenum fills up when it rains then drips out round the washer pipe grommet onto the fuse box

A new hole drilled in the plenum has sorted that but the fuse box is not easy to remove so I have had to bodge it for the time being relocating the starter relay to outside the box

domlinson · Oct 10, 2022

Just a small update... I've looked at the 2 white connectors in the passenger footwell, and I have a tiny bit of corrosion... Loads of WD-40 'Specialist' Contact Cleaner, and disconnected and reconnected the connectors loads to ensure a good mate between all pins, but no change in behaviour.

I've found a breaker very local to me who has tested good ABS ECUs for £85, so will go and pick one of those up later and give it a go.

Thanks

Mark Piercy · Oct 10, 2022

domlinson said:
Just a small update... I've looked at the 2 white connectors in the passenger footwell, and I have a tiny bit of corrosion... Loads of WD-40 'Specialist' Contact Cleaner, and disconnected and reconnected the connectors loads to ensure a good mate between all pins, but no change in behaviour.

I've found a breaker very local to me who has tested good ABS ECUs for £85, so will go and pick one of those up later and give it a go.

Thanks

All the connectors in both sides need to cut off and the soldered back together. The plugs were for assembly purpose only. The corrosion mostly comes from leaking from around the cabin filters.

Mark Piercy · Oct 10, 2022

Datatek said:
Yes, more clever design. The heater intake plenum only has a drain at one end, my parking slopes a bit so the plenum fills up when it rains then drips out round the washer pipe grommet onto the fuse box
A new hole drilled in the plenum has sorted that but the fuse box is not easy to remove so I have had to bodge it for the time being relocating the starter relay to outside the box

Some of the designs on some car is absolutely ridiculous... More more cars are being designed for a 10yr usage. After that the repairs are either expensive or costly in man hours....

kermit_rr · Oct 10, 2022

domlinson said:
Just a small update... I've looked at the 2 white connectors in the passenger footwell, and I have a tiny bit of corrosion... Loads of WD-40 'Specialist' Contact Cleaner, and disconnected and reconnected the connectors loads to ensure a good mate between all pins, but no change in behaviour.

I've found a breaker very local to me who has tested good ABS ECUs for £85, so will go and pick one of those up later and give it a go.

Thanks

At least some of the connections in the white blocks need a good clean signal, a quick clean and plug back in won't be good enough

The ABS sensors go direct and not through those plugs

domlinson · Oct 10, 2022

Thanks everyone.

So... these white connectors, I will get around to soldering and heatshrinking them to avoid any issues in the future.

However, are these connectors a possible cause of my ABS Fault? I've heard on some threads that they do have ABS related connections, but then some say that they don't and it's mainly EAS stuff in there.

Mark Piercy · Oct 10, 2022

A

domlinson said:
Thanks everyone.

So... these white connectors, I will get around to soldering and heatshrinking them to avoid any issues in the future.

However, are these connectors a possible cause of my ABS Fault? I've heard on some threads that they do have ABS related connections, but then some say that they don't and it's mainly EAS stuff in there.

And speakers

domlinson · Oct 10, 2022

So a 'tested and working' ECU is now installed and the problem is still here.

Exactly the same behaviour. Ignition on and within a few seconds ABS Fault pops up...

Maybe I'll go back to looking at those connectors.

kermit_rr · Oct 10, 2022

domlinson said:
So a 'tested and working' ECU is now installed and the problem is still here.

Exactly the same behaviour. Ignition on and within a few seconds ABS Fault pops up...

Maybe I'll go back to looking at those connectors.

Have you driven over 5mph? Pretty sure the fault message can't be cleared any other way. Only the codes can be cleared

ABS fault with no fault codes

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