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Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

2003 Defender 110 Td5 USW Stornoway Grey

Resistance is futile - well some odd earth results I think..

Right then.

Tother week to avoid a lunatic in a Beemer I dropped into hit a chuffin big pothole and although I didn't brake low and behold "The 3 amigo's" of ABS/TC/BRAKE WARNING lights came on.

.

However next time out no lights so thought I'd keep an eye out. Next time I hit a bump in the road (There's plenty round here) the came on again.

So off to the dealer to be told it's ABS pump failure and that'll be 2200+ cat and fitting.

But I don't exactly believe them.... a quick relay swap had them the lights off until either it was parked up and restarted or hit another bump. Not exactly sounding like an electric motor that's failed somehow.....

Fortunately parked next to it is another Defender with an identical ABS system that works. (Actually it's not quite true there's a vastly superior Series 3 parked next to it which has never had an ABS fault in 41 years!)

Swappage of ABS ECU's proved fruitless along with relays etc. But a review of resistances in the looms look promising:

As the ABS system injects a voltage even if the relay is off (ie the pump isn't running) to make a rather inaccurate assessment of the state of the pump motor any resistance in the wiring loom/circuit will affect the result.

Having tested the resistance and voltage of everything you can imagine between the two there is only one discrepancy of note. Unsurprisingly it's the figures for the circuit that runs from the ABS ECU to the pump.

Click image to enlarge

With ignition on but engine not running:

Working Defender: A or B to E = 4.7Ohms
Faulty Defender: A or B to E = 8.2Ohms

Working Defender: D to E = 0.2Ohms
Faulty Defender: D to E = 7.4Ohms

This makes me suspicious of that infamous earth stud K108 which can cause some fun and games.

So breaking it down.

Working Defender: D to K108 = 0.1Ohms
Faulty Defender: D to K108 = 0.3Ohms

Working Defender: K108 to E = 0.1Ohms
Faulty Defender: K108 to E = 7.2Ohms

Then if you do the test with the engine running they stay the same but start switching on electric stuff...

Working Defender with lights on: D to E = 20ish Ohms
Faulty Defender with lights on: D to E = 96ish Ohms

Working Defender with lights, aircon the works switched on: D to E = 100ish Ohms
Faulty Defender with lights and aircon on: D to E = 236ish Ohms!

Run out of time for tonight but I'm thinking that such a high earth resistance will be causing havoc.

Does anyone have any figures from their own vehicles?

They'd be muchly muchly appreciated!!!!!

Admin note: this post has had its images recovered from a money grabbing photo hosting site and reinstated

90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

26th Aug 2013 7:32pm

K9F

Member Since: 12 Nov 2009
Location: Bournemouth
Posts: 9610

2008 Defender 90 Puma 2.4 XS CSW Stornoway Grey

This thread but for a Puma page 3.......I slammed on the brakes and the same symptoms ensued.....

http://www.defender2.net/forum/topic2394.html?highlight=chaffed

Not wishing to teach 'egg sucking' but presumably to prevent parallel earths the ABS ECU, ABS Pump Relay and the connector should be electrically disconnected when carrying out the resistance checks? If you go through life with your head in the sand....all people will see is an ar5e!!

Treat every day as if it is your last....one day you will be right!!

26th Aug 2013 7:52pm

Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

Yep they should be disconnected depending on what you're testing.

I should maybe add I design/repair/ generally mess about with electrical systems on large industrial plants....

I'd seen that thread although I admit I've never had just ABS/TC lights on ever. Only all 3.

Belled out all ABS sensor wires on both vehicles. There's within a gnats fart of each other.

Some of the folk discussing that earth connector (K108) behind the coolant header tank is definately the next port of call. It's just a sod to get to! 90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

26th Aug 2013 8:11pm

Jimb1978

Member Since: 05 Sep 2012
Location: Huddersfield
Posts: 808

2002 Defender 110 Td5 Black LE Java Black

When I had the three amigos it was a bad connection on one of the terminals on the bottom of the relay under the drivers chair. I can't remember which one but it was obvious when I finally spotted it. It was caked in the green coloured corrosion and when I pulled the wire it came straight off the connector. Crimped and resoldered a new terminal on and job's a good un.

Hope you find the problem soon

Jim

26th Aug 2013 8:22pm

Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

Cheers Jim,

I'd seen your thread and have been through all the connections under the seat relating to the ABS system. Depressingly immaculate in these circumstances!

Next test will be to run a test wire from the battery earth to K108 and see if it works. For the minute though it can sit there! 90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

26th Aug 2013 8:26pm

Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

Well at lunch today I ran a strap wire direct from the battery negative to K108 earth stud. Result was less than 0.1Ohm earth at the ABS connector (It even improved the ABS connector to earth stud results)

Despite a couple of restarts it still has the lights on the second you start up.

So next plan is to get a data sheet for the ECU.

As I said above it appears that the ECU injects a voltage and looks for a resistance within the motor.

Obviously infinate and 0 are definate motor failure figures (or wiring issues) but what tolerance does it have on the Ohmic figure? Because whatever that figure is the working on is within it and the faulty one isn't.

Either way putting a few volts across a motor and measuring it's resistance is a very unreliable way of testing an electric motor unless you're looking for 0 or infinity.

So lets see who knows what that ABS ECU has in it's dataset....I have a sneaking suspicion Land Rover might not be so forthcoming. (If they know that is) 90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

27th Aug 2013 12:11pm

JWL

Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

With Hummers using the same modulator block there may be some values in the public domain on the other side of the Atlantic.

27th Aug 2013 1:41pm

SteveG

Member Since: 29 Nov 2011
Location: Norfolk
Posts: 660

Have you checked the sensor on the wheel that hit the pothole to check its still mounted ok, connector etc.

Personally I'd start here.

Cheers

Steve

27th Aug 2013 5:03pm

Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

I checked all the sensors they're perfect. And a sensor would bring up ABS/TC I believe not WARNING/ABS/TC

Far side of the pond has proved fruitful. Got an installation manual from WABCO website and although it doesn't have Ohm values for what is acceptable/unacceptable.

But what I did do was manually fire the pump relay. Pump worked a treat and low and behold the lights went off!

Still got 8 ohms between Pump positive and earth but now that's acceptable to the ECU!?!

I've made some enquiries regarding that figure.... 90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

27th Aug 2013 5:17pm

Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

Well Land Rover themselves claim not to know!!!!

ECU testing reckon it's a goner so a quick question:

Other than the re arrangement of the output ports whats the difference between the discovery unit and the Defender ABS modulator unit? 90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

16th Sep 2013 8:30pm

Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

Well I still don't believe the ABS pump has gone.

Lot of measuring of details between working and faulty LR shows that the ABS ECU is seeing a resistance a 5.6Ohms on the good one and 6.7Ohms on the faulty one.

And......persuade a spare ECU just plugged in on the faulty landy that all is well and head off and to an emergency stop on gravel (handy living offroad) and the ABS works..... for a while then the ECU says its curtains.

So not a penny will be spent on new pump until SOMEONE tells me what the criteria the ABS ECU uses to determine pump failure.

Bit worrying that my local dealer can't find out.

90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

17th Sep 2013 6:20pm

jimbob7

Member Since: 06 Jul 2013
Location: uk
Posts: 2055

Sympathies fella,I get the impression it's a black art fault finding these things,I'm gonna try sacrificing a goat if mine comes on again. Good luck with it.

17th Sep 2013 6:40pm

JWL

Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

Going back to basics, you can proove that the mechanical side of the system works(well the hydraulics do what they are supposed to do) the only moving parts, bit of guessing, within the modulator block will be the shuttle valves and these are controlled by the two solonoids which are themselves controlled by the ABS magic box which interprets the signal inputs. IIRC your 110 is slightly newer than mine(2002) but with mine I have the "shuttle valve failure 255 times" which on a Discovery is sorted by by-passing the pcb in the modulator and joining to the loom before the multi-plug to the modulator and continuing to earth. The Defender looks the same allbeit a different colour code on the loom.
I took the solonoid plate off mine and soldered new wires as described on a previous post above but the fault has returned but, when I opened the solonoid pack there was a lot of crud in the casing plus the insulation on the wiring was pretty dodgy

Click image to enlarge
I will, when I get the chance, open it all up again and see if I can replace the wires right back to the solonoids themselves as the wires themselves looked like they had started to break down with corrosion. A complete overhaul of the earthing points will be done as well. Personally I can't see that much else can be wrong, but that's my view from one that prefers a bigger hammer to a soldering iron!

17th Sep 2013 6:42pm

Landyphil

Member Since: 23 Jul 2012
Location: Lake District
Posts: 87

It's coming up with pump failure code rather than SLS but not having an internal wiring diagram of the module I'm still

the wind a bit.

Give me a diagram and I'll have a go at any electrickery.

90XS Tdci John Eales
110 CSW G4 Edition
88" Series 3 Racer

17th Sep 2013 7:53pm

JWL

Member Since: 26 Oct 2011
Location: Hereford
Posts: 3443

I know where you're coming from with the watering the breeze when it comes to seeing where the electrickery goes inside the boxes

Judging by the state/condition of the wiring even I as a bigger hammer agricultural mechanic have serious doubts about the integerity of the internal wiring. It would be nice to find a wiring diagram for a system that has been around for over a decade

17th Sep 2013 8:07pm

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