P38A ABS Fault on Dash, Nothing on Nanocom?

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Dodgy caliper won't have any effect on the ABS. I ended up buying a new caliper for £38 because mine was sticking, but it had no effect on the ABS.

I just found out I have a weeping pipe from the reservoir to the ABS unit and that's giving me a low brake fluid warning, but that also doesn't affect the ABS system (at least not while there is sufficient fluid in the system..).

It is possible that you may have a bad ABS unit. They are known to fail but replacements are available.

If the rear bleed nipple isn't allowing flow, it is a slight possibility that this could be the issue, but I doubt it.

If you have exhausted all other possibilities, then I'd be tempted to believe that the ABS system has gone faulty....
 
BrenK said:
No. Stays on permanently.
Kermit_rr ? Not checked to be honest. I’ll check.
Cheers.
Click to expand...

Checked all the teeth on the reluctor rings are good? No cracks?

What age is this vehicle? If 99 onwards with 4W TC (WABCO D) then you can record a trace with the Nanocom as long as you creep along at about 3 mph. Someone on here did it. @DanClarke, maybe?
 
Grrrrrr said:
Checked all the teeth on the reluctor rings are good? No cracks?

What age is this vehicle? If 99 onwards with 4W TC (WABCO D) then you can record a trace with the Nanocom as long as you creep along at about 3 mph. Someone on here did it. @DanClarke, maybe?
Click to expand...
@Grrrrrr , Not guilty M'lud. :D My ABS fault was the O/S/F sender (a pretty cheap fix @ £14.99). But, as I was concerned that it might be the WABCO-D ECU I bought one of those S-Hand on the bay of e (as I hear they are getting scarce?).
This unit is sat in my spares cupboard. If you do have a problem with the WABCO-D ECU unit, I understand @martyuk can fix what appears to be a common fault with it.
 
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DanClarke said:
@Grrrrrr , Not guilty M'lud. :D My ABS fault was the O/S/F sender (a pretty cheap fix @ £14.99). But, as I was concerned that it might be the WABCO-D ECU I bought one of those S-Hand on the bay of e (as I hear they are getting scarce?).
This unit is sat in my spares cupboard. If you do have a problem with the WABCO-D ECU unit, I understand @martyuk can fix what appears to be a common fault with it.
Click to expand...

Hmm. I know someone on here had an issue and posted up a trace because I made an Excel file to dig through it!
 
One thing I have found with the WABCO D unit is that if it isn't showing a fault at that particular moment (ie is intermittent) then when it comes up "No Faults Found" press OK, and then you have the blank box. Press the RH Arrow, and sometimes if there are historical faults logged, then it will now display them.

I looked at my mates one last night as he's been having random ABS Fault and Brake Light Failure messages for awhile - but not every time, and sometimes one, not the other. Going into ABS ECU showed no faults. Hit the right arrow, and got "Permanent Voltage Supply lost" (or something along those lines) and then pressed the LEFT button and it scrolled back to the top of the list of the logged faults, and it showed "Brake Switch Fault" looked at brake switch inputs and found and intermittent issue... repaired brake switch, and problem solved.

But the moral of the story... If it shows 'No Faults Found', Press OK, and then try the Right and Left arrows and it should bring up the last intermittent faults and give you an idea of where to look.

If it was the ECU that was faulty, then you would have "LH Rear Sensor Short To Another Sensor" showing as a permanent fault - which is the one I can repair.

Hope this helps,
Marty
 
Use Nanocom to check if brake switch one and brake switch two are cycling. They CANNOT both be open or closed at the same time. Or you will get ABS fault warning.
 
Though also as a side note... on the WABCO D system, in the Nanocom, they WILL show as both being OPEN or CLOSED at the same time (they aren't because of how the switch is wired though). The WABCO C system shows up as one being OPEN, the other being CLOSED and then them both swapping when the brake pedal is pressed.

There is an issue in the Nanocom software how it reports the brake switches on the D series ECU's and they both will read the same thing, so you should see them BOTH read OPEN or CLOSED at the same time - if one of them isn't changing, then that's your issue (as it was on my mates one last night).
 
wammers said:
Just read through the post. It would have helped immensely if you had quoted the year of the car in the first post.
Click to expand...
Sorry, my mistake. Thought I’d put it in the title like I did on the other thread I have running.
But for the sake of clarity it’s a 1999 2.5 DSE with Wabco D.
Cheers.
 
Right....
Someone earlier in thread had mentioned adjusting Brake switch so I had already got it out last night. Cleaned all contacts with electrical cleaner, pulled plunger out, refitted switch and let pedal do its stuff. Switch adjusted ok.
Plugged Nanocom in and tried the No faults trick and nothing is stored at all. (Still shows ABS FAULT on dash on start up though)
Checked Brake 1 and 2 operation and shows both Closed when not using brake and Both change to Open when pedal pressed.
Only thing that seems strange to me, but no doubt you can tell me if its normal, is when looking at the inputs on Nanocom, vehicle speed is shown on all 4 sensors as 1.7km even though car is stationery? is that a default setting or an error. All other inputs seem equal on the sensors.
Not going to have time over weekend, but guess next step is wheels off, pull sensors out and check rings?
Thanks as always.
 
Yes, 1.7 km is standard when the vehicle isn't moving. I don't know why - but as long as they are all showing the same, then it's generally OK.

Out of interest, what voltage are the sensors showing on the inputs page?

Going by the Brake switch operation that you've mentioned, that is all working as it should - as long as they change over together, then it's behaving - you'd see if it wasn't - my mates one would change over switch 2 first, and then only sometimes switch 1 would do anything.

I've had a few owners with the WABCO D system get in touch, and 2 of them have sent me ECU's for testing/repairs as they had been diagnosed as faulty. In both cases, the ECUs were fine. One of the owners got back to me and said that the root cause was a crack in the reluctor ring which was giving the fault (though his was actually showing up a sensor fault). I think the other owner had been having issues with sensor short to another sensor issues aswell, and he had replaced both sensors with aftermarket ones. I would have to go back over our emails, but I *think* he said he was chasing down and checking the insulation of the sensor against the axle sleeve where it pressed in - there was something he noticed about when it touched in a certain way, it would trigger the fault.. I've also read from another owner who had a similar thing - and he ended up putting one wrap of insulation tape around part of the body of the sensor somewhere (not the tip obviously) and that sorted it.

For some reason the WABCO C ECU's seem to just get on with it, but the D series units are a lot more finnicky about the sensors and the seating of them!

Oh, as a reference - wheel speed sensor voltage on the Nanocom should all read about 2.33V - I have one on mine the LHR (which I did replace with aftermarket, but then found it was the ECU fault) which reads 2.25V but still works fine with no errors.

Also... the Nanocom readouts for the wheel sensors for voltage (and I presume the speed) aren't as they are labelled.. If you get a fault code for XXX Corner, then the fault code is correct - but in the live data on the 'INPUTS' page the labels are wrong... they actually are:
Front/Right Label in Nanocom IS Front/Right sensor on vehicle
Rear/Right Label in Nanocom is Front/Left sensor on vehicle
Rear/Left Label in Nanocom is Rear/Right sensor on vehicle
Front/Left Label in Nanocom is the Rear/Left sensor on vehicle

It took me a bit of head scratching chasing a fault on my RR (when the ECU did fault) before I worked that out... I did mention it to Blackbox who make the Nanocom about updating it of later firmware released, but to my knowledge, it hasn't been corrected yet.
 
martyuk said:
Yes, 1.7 km is standard when the vehicle isn't moving. I don't know why - but as long as they are all showing the same, then it's generally OK.

Out of interest, what voltage are the sensors showing on the inputs page?

Going by the Brake switch operation that you've mentioned, that is all working as it should - as long as they change over together, then it's behaving - you'd see if it wasn't - my mates one would change over switch 2 first, and then only sometimes switch 1 would do anything.

I've had a few owners with the WABCO D system get in touch, and 2 of them have sent me ECU's for testing/repairs as they had been diagnosed as faulty. In both cases, the ECUs were fine. One of the owners got back to me and said that the root cause was a crack in the reluctor ring which was giving the fault (though his was actually showing up a sensor fault). I think the other owner had been having issues with sensor short to another sensor issues aswell, and he had replaced both sensors with aftermarket ones. I would have to go back over our emails, but I *think* he said he was chasing down and checking the insulation of the sensor against the axle sleeve where it pressed in - there was something he noticed about when it touched in a certain way, it would trigger the fault.. I've also read from another owner who had a similar thing - and he ended up putting one wrap of insulation tape around part of the body of the sensor somewhere (not the tip obviously) and that sorted it.

For some reason the WABCO C ECU's seem to just get on with it, but the D series units are a lot more finnicky about the sensors and the seating of them!

Oh, as a reference - wheel speed sensor voltage on the Nanocom should all read about 2.33V - I have one on mine the LHR (which I did replace with aftermarket, but then found it was the ECU fault) which reads 2.25V but still works fine with no errors.

Also... the Nanocom readouts for the wheel sensors for voltage (and I presume the speed) aren't as they are labelled.. If you get a fault code for XXX Corner, then the fault code is correct - but in the live data on the 'INPUTS' page the labels are wrong... they actually are:
Front/Right Label in Nanocom IS Front/Right sensor on vehicle
Rear/Right Label in Nanocom is Front/Left sensor on vehicle
Rear/Left Label in Nanocom is Rear/Right sensor on vehicle
Front/Left Label in Nanocom is the Rear/Left sensor on vehicle

It took me a bit of head scratching chasing a fault on my RR (when the ECU did fault) before I worked that out... I did mention it to Blackbox who make the Nanocom about updating it of later firmware released, but to my knowledge, it hasn't been corrected yet.
Click to expand...

Thanks Marty. Off the top of my head I remember that two of the sensors were showing 2.33v either both front or both rear, but the other two were showing either 2.6 or 2.2 something, but was the same reading for both. I'll check again in the morning. Still at a loss as to why it shows Fault on the dash, but nothing comes up in diagnostics, but guess it's just one of those oddities, and assume Nanocom can't diagnose everything.

Will get there in the end with you fellas help I'm sure, but bloody hell it's aggravating the hell out of me, haha.
 
RangeRoller dt said:
It’s the best you can get.
JLR or BMW themselves will charge you for scratching their heads for a week with s P38 They can’t compete with these guys on any level
Click to expand...
Without a doubt ! Some of the fellas on here know more about these beasts than LR, and certainly more than I could ever hope to know (let alone understand :confused:) that’s why I keep coming back. Not just for my silly questions but the stuff I’ve learnt reading other threads and the hundreds of searches I’ve done, has been invaluable already.
 
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