OK. When I bought my truck (June 2021, 2004 Disco II HSE) it had intermittent 3 amigos. They came on and went off randomly, filling the gas tank was a flawless way of getting them to go off. I figured this had to be the ground fault error and I tackled the job in December. I took the shuttle valve assembly unit off and the wires inside were in horrid shape. The plastic insulation was cracking and peeling off all of the wires. At one point in my life I was halfway decent at soldering etc so I cut the wires and replaced them with new wires inside of the unit. Wasn't the best work I'd ever done, but it appeared solid. While I was at it, I did the option B fix. Around a week later, the wife and I were out on the beach and the truck started making a horrid noise in the front, lurching forward like intense braking (only going 15 mph so it wasn't too bad) for maybe 2 seconds. After that, everything was fine. I had put the truck in low just to give it some time in low and thought perhaps something was wrong with low gear. I mostly forgot about it because it didn't happen again. For a few weeks while searching for a new daily driver, I was using the disco as my daily driver. With an over 35 miles one-way commute, I would have expected any issues to arise, but nothing went wrong, the truck ran great. The last two weekends I've taken the truck out on the beach again and the same noise / breaking sensation has happened again. The first time I hit a big bump and when the truck came down it "locked up." Yesterday, I saw a bump ahead of me so I took my foot off the gas to slow down, hit the bump going maybe 10 mph, it was little and barely jostled us in the cabin, and low and behold it did it again. This was the most egregious of the events. It felt like we were going to get buried down and when I went and looked at the tracks in the sand it looks just like I had locked the brakes up, yet I hadn't touched them.

So my question is this: Can the ABS system cause the brakes to lock up like this? I'm guessing that there is some area where wires that shouldn't be touching are during these bumps, but only sometimes. I don't have the 3 amigos lights anymore, at least they haven't come back on yet (I don't drive it a ton when it isn't summer). The wife is rightfully concerned that it will do this while driving down the highway.
Is there anything else that could be causing this to occur? I was wondering about axels/differentials/driveshafts but based on my readings they seem very unlikely culprits.

Of course, the truck also threw out a p0307 code at me yesterday, so I have to work on that as well. I'm thinking that will be a straightforward replacement of the plugs/wires/coils as they were due for it anyway. That happened after taking it through a carwash to remove the salt, so I think the high pressured water didn't help anything and perhaps caused an o2 sensor to fault, but we will see what the wires, etc do first. All that being said, I won't be driving until I get the p0307 code fixed to test the "braking" issue.

 

It sure sounds electric to me, however my understanding is that the default would be to not lock up the brakes. Is it happening on sand, the beach? that part was unclear. I can see this being a traction issue.
On the option B, maybe confirm the ground?

 

You need a scan tool which can read the ABS faults. I'd say you have a wheel sensor acting up. If you ever hear the ABS modulator activate just when driving normal it's usually a hub/sensor causing false readings so the ABS has no clue what to do. Read the codes & go from there = only real way to fix it IMHO.

 

Sorry, Yes it happens when on the sand (beach). It hasn't done it on the road thankfully. It also happens in conjunction with going over a "bump" of sorts, think speedbump, but made of sand.

I didn't think of reading the codes like a dummy. I have a foxwell, I will check them when I get home.

 

I just got in from checking. There are no ABS codes stored or pending. The ONLY codes I can find are p1412 / p1415 / p0307. I tested the ABS pump cylinder and it reminds me of what is occurring when this all happens.

 

Are you sure you are looking for SLABS codes, and not general engine codes?

 

Not sure the foxwell can do live data, but say for example with my Nanocom I can watch the ABS Sensors live data speed. If one varies vs the rest = I investigate. It sounds like it's so intermittent it hasn't thrown a hard fault, but it will eventually as it gets worse. Could be as simple as a bad ABS Sensor connector (known to crumble) and it's getting damp or shorting when you go over bumps.

 

Sorry I wasn't clear. I checked EVERY menu the Foxwell has available to check. I checked the ABS codes first, nada. I then checked everything else, including the general engine codes which is where the codes came from. I'm still noob enough I don't trust myself all the way in knowing which codes I'm checking.

I can check live data with the Foxwell. It is able to give me wheels speeds, engine torque, valve volts etc. I attached a pic of part of the live data screen. I will have to hook it up and take it for a spin. Hadn't considered it would show variations like that and what they might mean. Makes sense though. I think you're right that it is something that is so short it isn't tripping the system fully yet. Hoping it doesn't get me stuck on the beach, that can be an expensive tow out.

 

ABS faults won't leave ya stranded. Once it actually triggers hard faults = system is pretty much inactive. Heck most D2's I've ever come across have had the 3 Amigo's on for most of the D2's life until I came across it lol.

 

Three amigos off? Have you tested the HDC yet? Pull the ABS relay and do a bump test.