2002. P38 4l thor/motronic. ABS, TC lamps

Good morning.
My nanocom says "no faults found" in WABCO page. Even so, I clear faults. The only other faults, anywhere are in the MOTRONIC page, P0175 mixture adapt. P1592 rough road. both no longer present and can be cleared.
All corners have had hubs/bearings, oil seals, CV joints, abs sensors. I've renewed the abs accumulator and pressure switchalso both brake switches. Double bled the braking system as per gospel. The abs pump kicks in on the fourth pedal depress, sometimes five.
My problem started with occasional appearance of the abs and tc lamps only on slow manouvres. e.g. Parking/reversing/back-forth. Re starting cleared them off each time.I could do thousands of miles in between. Now, the abs blink produces "traction control fail" on the dash with the abs tc lamps remaining on. I get the "traction fail" on switching off. In addition, "abs fault" flashes up mometarily after a short number of metres never to be seen again. I get identical resistance readings both at the sensor and ecu end of the loom. I've contacted blackbox who say if nanocom says no faults and ECU settings can be read then, there are no faults and the ecu is likely to be ok. I've renewed the relevant relays and checked fuses.
Knowing me, the obvious or stupidity can't be ruled out.
As ever, any help would be appreciated. best regards. P

My thought are

1) are the ABS sensors all the way into the springy bushes and staying there?

2) is wiring all good at connectors?

Failing that the 4W TC models seem to suffer from a few failure points in the ECU that don't seem to bother earlier models. @martyuk is the expert there. He's managed to save a few which compared to even a second hand unit off the Bay is a bargain.

Thanks for your early thoughts. New clips and sensors shoved in to touch reluctor rings. Not a definitive test, I realise, but crawled around and watched all sensor inputs behave similarly. I'm a big fan of Marty's already but I'm in southern Spain presently. I'm wondering if a weary abs pump can throw up the TC and abs lamps without recording a fault in the ECU.

A failing alternator;/battery can through up false warnings/or a bad earth ...

dubbleRR said:

A failing alternator;/battery can through up false warnings/or a bad earth ...

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+1 ^^^^^^
I have had 2 alternators go "iffy" on my P38 and while the battery light was out, it was NOT charging or only barely charging the battery.
The low-volts would throw up spurious ABS & TC lights/alarms.
Usually this happened after going over a pot-hole and I assume the jolt was enough to disturb the precarious state of the alternator brushes.
Check you have 14.3V or better @2,000 RPM with everything switched on.

Assuming it's a P38, check the viscous coupling has not seized.

I would never have thought of that. But that means nothing. Can I assume that a seized viscous coupling would cause erratic delivery of power through the transmission train thus firing up the "rough road" signals which in turn have an effect on traction control? Gone some way into researching the subject since your suggestion and I'll go ahead with the tests I've gleened thus far..Thanks for a thoughtful response. regards.P

supapete said:

I would never have thought of that. But that means nothing. Can I assume that a seized viscous coupling would cause erratic delivery of power through the transmission train thus firing up the "rough road" signals which in turn have an effect on traction control? Gone some way into researching the subject since your suggestion and I'll go ahead with the tests I've gleened thus far..Thanks for a thoughtful response. regards.P

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To test the viscous coupling jack a front wheel with handbrake on and transmission in neutral. You'll need a torque wrench and a 32mm socket for the hub nut. My refurbed transfer box took 70nm to tease round very slowly without clicking. If you cannot get it to turn without using 150nm on the torque wrench then I'd say it needs replacing.

Grrrrrr said:

To test the viscous coupling jack a front wheel with handbrake on and transmission in neutral. You'll need a torque wrench and a 32mm socket for the hub nut. My refurbed transfer box took 70nm to tease round very slowly without clicking. If you cannot get it to turn without using 150nm on the torque wrench then I'd say it needs replacing.

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No real need for the torque wrench, just apply heavy pressure to try to rotate the tyre it should move very slowly with constant pressure.

All bets are off, thank you all. Wheel up as specified. Wheel brace on with jack handle extension. Turned steadily one handed whilst fiming with with the other hand. No clicks.

supapete said:

All bets are off, thank you all. Wheel up as specified. Wheel brace on with jack handle extension. Turned steadily one handed whilst fiming with with the other hand. No clicks.

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No issues there then. Onwards and upwards ...

Backwards and downwards. In fairness, on reflection, I'm taking much for granted. Before I set off, amongst a host of other things, I renewed the alternator and battery.
I'll now go and do some basics. Out with the ol' multimeter and nanocom. It's blistering here, at least I got the aircon flying.P.

Bonnet up at the battery clips 12.4v nothing on
13.8v tickover everything on
13.8 2000rpm everything on
Nanocom engine ecu batt voltage 12.45v ign on
13.68 tickover
13.78 2000rpm
Nanocom abs ignition supply 12.35 ignition on
13.58 tickover
13.71 2000rpm
faults on motronic P1592 6 times intermittent after 12mile run.

That's it. and thanks

mine use to read 14.2 with all the accessories on and around 14.6 unladen with the motor running of course..

I'd say she's undercharging slightly..

Have you investigated the white connectors behind the drivers foot kick panel. This problem could be caused by these connectors corroding.

I've seen this many many times.

Drivers kick panel. I've gone to town on the near side more than once. Never thought of there being any on the driver's side. Next job. Thankyou. P.

supapete said:

Bonnet up at the battery clips 12.4v nothing on
13.8v tickover everything on
13.8 2000rpm everything on
Nanocom engine ecu batt voltage 12.45v ign on
13.68 tickover
13.78 2000rpm
Nanocom abs ignition supply 12.35 ignition on
13.58 tickover
13.71 2000rpm
faults on motronic P1592 6 times intermittent after 12mile run.

That's it. and thanks

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13.8v is the old alternator set point. The one used on oil burners. You can upgrade for about £20.

Need new RF receiver to stop spurious RF draining battery. @brianp38dse has a cheap second fob fix and @martyuk has a more elegant solution. The price of the Land Rover fix ... Well, make sure you're sitting down and not near anything dangerous when you look.

Done the RF. Receiver thing ages ago. Three phase overhead cables, phone lines, WiFi assunder. I'll do more homework on your other suggestions. Will the extra 0.4v help me in other ways? I take it upgrade you mention is on the alternator. Thanks again.

Grrrrrr said:

13.8v is the old alternator set point. The one used on oil burners. You can upgrade for about £20.

Need new RF receiver to stop spurious RF draining battery. @brianp38dse has a cheap second fob fix and @martyuk has a more elegant solution. The price of the Land Rover fix ... Well, make sure you're sitting down and not near anything dangerous when you look.

Click to expand...

Mobiletron VR-VW010 regulator with a set point of 14.7 volts is what I'm using. Google it, they can be found for less than a tenner.

Gone connector crazy driver's side. When I saw the plethora of earth cables I thought "that's it!" Cleaned, recleaned, made and remade the blocks many times. I was really hopeful. No joy. But thanks. Things are getting ruled out in a structured fashion, though. Regards.p.