Hi Greyhound,
It sounds to me like the connection to one or more of the valves in your ABS modulator might be iffy, either not connected, or shorting to a wire on one of the other valves. I'd check all the wiring between the ABS controller (C0506) and the ABS modulator connector (C0501). Check for both continuity, a short to any of the other wires or a short to ground. Also have both the connector at the ABS controller and the ABS modulator connector unplugged while checking.

I suspect what is happening is that as you accelerate and the right rear loses traction the TC activates and applies the brakes and starts actuating valves to stop the right rear from spinning. If the valves aren't actuating correctly, not releasing when they should or the wrong valves are actuating then it might cause the symptoms you are describing.

Goodluck!

Hope the rest of the drive goes as smoothly as it has started 😃

Thanks for the info mad-as, and I am glad I am not the only one with this requirement!
I know the Landcruisers and some other 4x4 SUVs disable ABS when the transfercase is locked.

I have completed the prototype design and ordered the PCB and components.

So the unit should be able to disable ABS and TC with the push of one button. A second button will disable TC only.
The most basic implementation won't be able to disable ABS but keep TC active because the ABS and TC both use the same solenoid valve to each wheel station.

I have an idea to monitor the brake pedal input and then a third "mode" can be programmed where the ABS and TC are disabled only when the brake pedal is being pressed. When the brake pedal is released both ABS and TC will then be active again. This should work in a similar fashion to only disabling the TC, but will need to be tested first.

I have also added CANbus functionality to the board. My "want" is to install a secondary CANbus in the vehicle which can then monitor and actuate different modules as I add them. A little display can then be places somewhere in the dash which could display this information. It won;t be used for anything at this stage, but adding the functionality costs nothing if the components aren't populated on the PCB.

I should have the first prototype ready for code in about a weeks time.

Not quite hill descent control, but rather ABS that prevents wheel lock even when the brakes are not being applied.
I was heading down a wet muddy hill with large, flatting rocks that made the surface very slippery. I had the initial version of my ABS disable switch installed and had the switch pressed for this descent, so the ABS ECU had no way of knowing I was pressing the brakes. Even a light application of the brakes would lock one of the front wheels, which was then immediately released again, even though I kept applying the same amount of brake pressure. The vehicle just kept increasing in speed down the hill and I just had to hold on and try to keep things under control using steering, applying the brakes or not made little to no difference down the steep sections.

This was the type of hill that I would have preferred crawling down as slow as possible, but the ABS didn't allow this. I would, for example, like to slowly step down a rock with the front right wheel locked so that it is dropped down the step and then gains traction on the bottom stopping the vehicle immediately. This isn't possible because the wheel locks as it goes down the step (no traction as it drops down the sheer face), the ABS releases the brakes as it locks, the vehicle moves forward letting the front left get to the step and also drop down. The ABS then releases the front left too which adds to the momentum of the vehicle which then forces the front right to start sliding which the ABS then releases again and so the viscous circle continues.

A similar thing happens while driving at higher speeds on a gravel road. The stopping distance is greatly increased because of the ABS. Yes, you gain more control because the vehicle can be steered, but applying brakes correctly without ABS would still allow steering control to be retained. Also, sometimes it is more important to just stop as quickly as possible without needing to steer. A sudden ditch on a gravel road cannot be steered through, it is better to come to a stop before the ditch even if vehicle steering is compromised!

Anyway, above my reasoning for wanting to disable ABS. Lots of typing and reading, but it forces me to think through the scenarios which helps me understand what I actually want. Thanks!

I had a look at the hydraulic circuit diagram yesterday and it seems I am going to be able to disable the ABS and TC together or disable the TC on it's own, but not the ABS on it's own. I was hoping that I would be able to disable only the ABS, but keep the TC active but it seems this won't be possible. I'll look through the diagrams again this morning and see if I come to the same conclusion as yesterday and then move forward with the PCB design.

dave3d wrote:

I have only just done the cover so the job is not 100% finished. So far I have just filed the edges to remove any roughness. It is still bright metal.
I was going to use Tiger Seal to bond the bottom frame bit to the metal. Maybe I should paint round with Hammerite or Rustoleum first.

Let me know when you want the files. You need a largish print bed of 230x230. My old one was only 200x200.
I printed it in ABS as I said, but ABS warps terribly. You may be better printing it in PETG or even PLA, it's easier.
I used 6mm nuts and bolts and 8mm screw inserts to screw the lid on.

Thanks!
I've bought an Ender 5 Pro that has a 220x220x300high print volume, so just too small. If you send me the CAD model I can just split it into two parts and glue them together after. Or maybe just shrink it down a bit to fit my bed. You've already done the hard part of fitting it to the contours of the bed correctly, in essence that is probably the most important part of the CAD model!

dave3d wrote:

Anybody who has other suggestions what to make, speak now. I was looking at fitting two air compressors, one outside the EAS box on a special bracket. I know Marty has fitted two compressors. Maybe a pressure gauge bracket for under the bonnet.
I am doing a windscreen ice scraper at the minute. Not needed in SA.

We did a snow trip to Lesotho this past winter, and the snow scraper would definitely have come in handy!

My first attempt at disabling ABS without influencing the working of the traction control was to prevent the ABS ECU from "seeing" the brake pedal input. The thinking here was that the ECU used the brake pedal as in input to decide when to activate ABS.
I passed the C0504 Pin7 and Pin14 connections through a DPDT pushbutton switch in the cubby that fed the ECU with a fixed state (NC for Pin7 and NO for Pin14) when the pushbutton was pressed. This meant that the ABS ECU always thought that the brakes were released even when pressing the brake pedal. Releasing the pushbutton switch meant everything worked as normal.

This didn't work! The ABS still activated even though the ECU didn't see the brake pedal state changing.
My assumption was wrong and the ABS ECU doesn't use the brake pedal as an input to activate the ABS. This also means that ABS will activate even when you are not pressing the brakes but only slowing down using engine braking. I've have since experienced this on a steep muddy descent.

I think this means that the ABS is only monitoring the wheel speeds and if the average is decelerating then ABS is "armed" and ready to intervene if one wheel is decelerating quicker than the others.
The inverse would also then be true for the Traction Control (TC). If the average of the wheel speeds is accelerating then the TC is "armed" and intervenes if a single wheel on an axle is accelerating faster than it's counterpart (or the average, I'm not sure, but RAVE seems to imply the average).

My current plan is to intercept the drive signals to the ABS Booster unit and prevent the solenoid valves booster unit from being energized when the ABS ECU attempts to do so.
This should allow me to either prevent ABS activation or to prevent TC activation (loose sand).

Any thoughts?

Hi Dave,
How did you finish the edges of the sheet metal to prevent rust?
I have a raised air intake that I'd like to get fitted this December, but I haven't decided how to deal with the cut edge of the sheet metal. It doesn't need to be pretty since the intake will cover it by quite a margin, but I don't want it to rust under there!

I've also just purchased a 3D printer, so at some stage I'll ask you to please send me your fuel pump cover files. Probably next year sometime.
Your cover looks good!

I got my BBS MSV licensed for the full P38 yesterday, and also fitted and tested the new to me UK ECM.
The ECM now enters closed loop fueling and is adjusting the trims. That's a win!

ABS Controller & Connector Info

C0504
Junior Power Timer, 17P
Partnumber: 1355204-1 (black housing, not available)
Alternative Partnumber: 1355204-2 (red housing, unconfirmed fit)

C0505
Junior Power Timer, 9P
Partnumber: 1-967621-4 (Grey)

C0506
Junior Power Timer, 15P
Partnumber: 1-967623-1 (Purple)

ABS & Traction Control Solenoid Drivers:
Infineon BTS612N1 (Smart Two Channel High-Side Power Switch)
Various output protections as well as open load & short circuit diagnostic capability.

Yes, I've already adjusted the pot on the back of the cluster, and the speedo now over reads by 1km/h at 100km/h. Perfect, but the trip meter still under reads by around 9.8% (if I remember correctly).

While I'm busy with the ABS disable I might aswell get the speed signal to the BECM sorted too 😀
(and do it in such a way that removing a bit of plug and play hardware reverts things back to standard).

Gathering data.

Rough Road Signal:
ABS Controller C0504-Pin4 --> ECM C0637-Pin34
Amplitude: Battery Voltage
Frequency: 2.38Hz
Duty Cycle: 25% = Rough Road OFF
75% = Rough Road ON

ABS Warning Light Signal:
ABS Controller C0504-Pin18 --> BECM C1288-Pin10
Amplitude: Battery Voltage
Frequency: 5Hz
Duty Cycle: 50% = Warning Light ON
100% = Warning Light OFF

Traction Control Warning Light Signal:
ABS Controller C0504-Pin17 --> BECM C1289-Pin12
Amplitude: Battery Voltage
Frequency: 5Hz
Duty Cycle: 50% = Warning Light ON
100% = Warning Light OFF

Speed Signal:
ABS Controller C0504-Pin3 --> BECM C1289-Pin11
Amplitude: Battery Voltage
Duty Cycle: 50%
Frequency: Varies with speed (detail to be added)
221.7Hz = 100mph = 160.3km/h

ABS Schematic Diagram (2001 Petrol)

I'm going to use this thread to just dump information as I gather it, and perhaps think out loud about what I'm busy with. Chime in if you have anything to add, please!
Also, all information here is possibly correct, possibly not. Use it at your own risk! (especially because what I do here might interfere with the vehicles ability to stop)

Vehicle:
2001 4.6 HSE Thor.

Aim:
1) Develop a controller that will allow me to intercept and correct the speed signal from the ABS controller to the BECM to correct for different diameter tires.
2) Have a way to disable ABS at the push of a button without interfering with the working of the traction control.

Thanks for all the options, all would work great except that I actually want to maintain the ability to do diagnostics.
I've spoken to BBS and it is a hard no from their side, no-upgrade fee structures are possible so it is the full 1500EUR for me.

I'm just waiting for the exchange rate to improve a little and then I'll bite the bullet and buy the full P38 vehicle license to replace my VIN locked one.

The immobilizer fix looks like a really interesting project, I've been following PsiDOC's thread here and on RR.net.
I'm half tempted to get one just to play around with!

Anyway, there is absolutely no rush for me to get any of this done, the RR is running beautifully and getting used quite a bit.

In my case I went for the Faultmate because it requires a laptop to do diagnostics (a con for many) but I prefer the user interface of a laptop over the handheld display of the Nanocom. Additionally the SM035 module is only available for the Faultmate, not the Nanocom. The SM035 module allows a deeper dive into the BECM and is something most users will never need or use, they would rather pay for this service. In my case, being here is SA far away from such services, I decided to rather have this available as an option should I need it.

For better or worse that was my thinking while choosing the Faultmate just over a year ago. I also bought a little cheap laptop that lives behind the seat in the RR to be used with the Faultmate and this laptop obviously has the RAVE manuals on it and all the other bits of faultfinding and diagnostic information that I collect as I go along. Nice to have it right there always in the car when needed!

I have contacted BBS again and pointed out again that I would like to "upgrade" from a single VIN license to the full monty and if they are not willing to offer a reduced upgrade fee instead of the full amount. I'm hoping they are willing, it'll make the capital outlay much less making the decision to upgrade easier to stomach.

Hi Dave,
Yes, I am locked to a single VIN.
I have discussed upgrading to the fully monty covering all P38s, but they are unwilling to offer me credit for the modules already purchased.

How did you manage to upgrade from the single VIN license? Or did you pay the full price?

Full Monty is this: https://blackbox-solutions.com/shop/product/mp112
VIN Locked: https://blackbox-solutions.com/shop/product/mp015 (this is what I have, but I have also added SM029 to read all the newer gearbox ECUs)

Update:
The new to me ECU has arrived from the UK, but I have hit an unforeseen hurdle. I need to update the immobilization code in the BECM to match the ECU (which my Faultmate can do and was expected) but I can't access the new ECU with the Faultmate because it is locked to the serial number of my old ECU.

Is there some other way for me to read the immobilization code from the new ECU? An "unlocked" software module from BBS that will be able to read bot ECU's costs 175EUR, which is quite a bit, so if there is a cheaper way of finding the immobilization code then that would be awesome!

Haha! Maybe, maybe not.
I like the P38, and I wouldn't mind another in the family once this one is they way I like it!

Ah, I wasn't aware of that. Oh well, now I know for next time.

I also thought of doing that, but I decided that the risk is that the 2nd hand ECM I purchase might have some fault and the only way of knowing would be to test it. Having the quite expensive Tornado map loaded on it and then finding out that the controller is faulty would be a bit of an expensive realization!
Hence the roundabout way of doing it.

ECM ordered from Ebay. Thanks for the tip! It should arrive with my freight courier by next week and then will likely take another week to get to me.

Interesting story, so weird how things have changed. Now SAA has been managed into the ground, had bailouts from our government to the tune of around 21billion over the past few years and still they are not a going concern. What car club did you run if I may ask?