I've had intermittent three amigos lights for many years. I think I finally understand enough about the problem to get it fixed. I know there are lots of threads on this, and I have read a bunch of them, but they tend to be written by and for people who know a lot more about these things than I do. My hope is that someone will review this summary and let me know what I've got right and what not.

There are two main problems that can arise with the ABS system:

1. A hardware failure, often the shuttle valve switch, but it can include up to replacing the entire ABS module.

2. A ground wire failure that can cause the three amigo lights to appear when in fact there is no problem with the system.

I've scanned the codes and there is one for the shuttle valve switch. I've purchased the kit from Falconworks, which includes replacing the seals.

The kit also includes instructions for fixing the ground wire problem, and there are some reasonably helpful step-by-step YouTube videos on this as well. (I believe the ground wire fix is often referred to as "Plan B.") My understanding is that this involves identifying the existing ground wire and bypassing it with new wiring attached to the shuttle valve.

I've seen conflicting advice as to whether the brake hydraulic lines need to be disconnected and the ABS module removed from the vehicle to do this work. I know that if the brake lines are disconnected, a full three-step power bleed of the brake lines will need to be done.

Comments, pointers, etc would be much appreciated. My mechanic friend (retired fleet mechanic with a full shop including lift in his backyard) is highly skilled in dealing with both mechanical and electrical issues generally, but he is not a LR specialist and he has not dealt with ABS system repairs before.

 

plan B is pretty easy to do and with most D2s it's a matter of when it will need to be done, rather than if. i have completed plan B and replaced the shuttle valve switches on three D2s and by the last two was able to do it without removing the ABS module and with out disconnecting any of the hard lines going into it. i was able to wedge a 1x4 under the ABS unit and raise it high enough to uninstall and then reinstall the shuttle valve switches. of course, if you are planning on doing a brake bleed or flush after, then it's pretty easy to disconnect the hard lines and work with the ABS unit on a bench.

 

Agree, I now do plan b by removing abs unit from mount and twisting it up and out of the way enough to get at the switch face plate a d remove it. No bleeding needed.

 

How is the SLABS modulator diagnosed to be sure/confirm it failed the part that performing the option B fixes it ?
Is that about probing the resistance when brake pedal is pressed ? (This is not about solving the 3 amigos fault; is about fixing the modulator)

When the something/cover underneath the modulator is removed, should be dry, wet or drip brake fluid ?

 

Dry, if you have the shuttle valve switch fault it is the internal ground fault, 99.9% chance. All the plan b mod does is move the wiring circuit external instead of internal. I have never seen a failed switch or a failed sls ecu cause the shuttle valve switch failure.

 

Thank you, Extinct. Always good advise.

Seems to me the comments to repair option B are very often together with crumbled insulation of the wires. Makes no sense to me. The simple circuitry I see is :

Plug pin1--------------------------------Solenoid1----------------------------------Solenoid2--------------------------------Plug pin2

The plug is internal, brought by the outside for a more reliable and visual reach as you say. If there was no insulation at all, the connection still exists to the solenoids. If the firmness of the plug connection fails; then I understand the need for surgery.
If continuity is probed from ground to the terminal at the modulator plug that connects to the end solenoid and shows proper resistance of both solenoids in series, would the option B surgery be needed ?
Is the firmness of the contacts of that internal plug the unreliable one, that is modified by soldered joints instead ?

" I have never seen a failed switch" --- ¿ Are these switches actuated by hydraulics or solenoids that actuate hydraulics ? Or electrovalves ?

At ----> https://www.roverparts.com/resources...-discovery-ii/

Time stamp 1:08 is "solenoids"
Time stamp 2:13 is "shuttle valve"
Did not see a place when named "switches"



I hope the Wabco company learned a good spanking lesson from their unreliable brakes engineering in our cars and will never goof again.




Robbery.

 

From memory when I posted these oscilloscope probings (the faint noise) a decade ago ---> https://landroverforums.com/forum/di...35&gid=1&pid=2
Pin 9 goes to 2 solenoids in series to pin 8 ground. 3000 ohms means the resistance for both solenoids in series at 1500 ohms each.
----> If pin 8 to chassis/battery(-) is good, clean solid zero ohm; and pin 9 is ~3000 ohm to chassis: there is no need to perform the modulator surgery, right ?

Some day I will play with the terminals and pump to be able to purge air out of the system by a jumper from the battery... Will publish.

 

The internal PCB is what cracks and causes the 3 Amigos within the Wabco Unit itself. The insulation is just a side effect of old age. Heck I have honestly used some 3/32 heatshrink and placed it over the crumbled wires on a stock shuttle valve switch and then performed Option B to a perfectly working system. After Option B is performed your only faults will be the ABS sensors themselves.

 

In my experience of Discos over the years, it’s generally two things that cause “amigos” -- multiple warning lights.

#1 -- your #2 (fixable with “plan b” mod) and in the old days, LR dealers used to replace the entire expensive WABCO module because they had no idea what was going on. I had an 03 that had it replaced I think twice under warranty when new? Always came back too lol.

#2 -- Wheel speed sensors not playing nice with SLABS ECU's. I think the wheel speed sensors and its wiring have gotten better, this was an issue 10-15-20-25 years ago more than it is now. And there was a recall to replace the SLABS box but I still see D2’s with the recalled box and 3 amigos.

 

I had intermittent 3 amigos years ago and decided just to install a new shuttle valve and do option B if the problem returned. It never did. The wiring in the old shuttle valve was in pretty bad shape. I did not remove the ABS unit for the install. As others have mentioned it’s very easy to remove it from the mount and bend it up a bit. The entire install took maybe 20 minutes.