3 Amigos - Help me Hunt!

[Mcl1043]

This could be fun...

I've had three amigos ever since I got my 99 D2 in 2017 (younger, broker, clueless). I've restored just about the whole truck at this point, now I just have to battle 3 Amigos.

I started with the Option B bypass (ground one side of shuttle valve and splice other into the green/yellow on the modulator plug) - no dice. Since I do everything backwards, I checked continuity on the shuttle valve switch itself. I had 3 ohms consistently, even when I pressed down on one or both sides of the switch (from what I hear, it's supposed to go to 2 ohms when I press a side and 1 ohm when I press both). Finally, I bought an LR code reader and checked it out because I didn't want to replace the shuttle valve for no reason... I got 12 codes in return:

0204 - ECU Ground or Reference Ground Fault
0140 - Shuttle Valve Switch Long Term Failure
0308 - Front Left Outlet Valve Open Circuit
0320 - Rear Right Outlet Valve Open Circuit
0420 - Rear Left Sensor Output Too Low
0440 - Front Left Sensor Output Too Low
0480 - Rear Right Sensor Too Low
0680 - Rear Right Sensor Electrical Failure
0820 - Rear Left Sensor Signal Erratic
0840 - Front Left Sensor Signal Erratic
0880 - Rear Right Sensor Signal Erratic
0B10 - Shuttle Valve Switch Electrical Failure


The help I need is to decipher these codes. I can't tell if one of these problems is tripping everything, if they're all issues, solutions? Let me know if I should try anything and I'll give it a shot. If anyone can link another thread that'll help me out, I'll go ahead and delete this one, don't want to oversaturate.

Thanks guys,

 

[discostew]

I would clear those codes and see what comes back first. I’m thinking that ground fault is the one I would go after first. Check the grounds behind the left headlight/ under the air cleaner box. The shuttle valve codes are probably going to need a modification you can find tons of info on around here.
I think it’s hard for me to accept that all the wheel speed sensors have failed. So I would hope the ground it’s using to run all of them is your problem with those.

 

[Mcl1043]

I would clear those codes and see what comes back first. I’m thinking that ground fault is the one I would go after first. Check the grounds behind the left headlight/ under the air cleaner box. The shuttle valve codes are probably going to need a modification you can find tons of info on around here.
I think it’s hard for me to accept that all the wheel speed sensors have failed. So I would hope the ground it’s using to run all of them is your problem with those.

I agree about the sensors - it seems a bit radical to have all go out. I'll start with that ground, then search around for some shuttle valve solutions. I'll let you know what happens.

Thanks for the reply.

 

[mark.kellgren]

There is a mod for the ground to remove it from the connector as a bypass, and hard wire the ground. The connector on the ABS modulator can fail, which causes all hell to break loose. I did that mod on 2 discos, along with the Falconworks shuttle valve upgrade kit, and never has ABS problems after

 

[mlnnc]

I concur. Clear the codes and see what comes back first. Then, address that and move on.

I have had The Boys from South of the Border in my truck for three different faults - shuttle valve switch electrical failure (addressed by the Option B solder joint bypass in Feb. 2011), a right rear sensor code and a left front sensor code. In a LARGE percentage of cases the sensor codes are due to problems with the electrical connectors back to the SLABS (computer) box, and NOT with the sensor itself or the hub.

So clear the codes, see what comes back first, and let us know. We're here to help. Good luck.

 

[discostew]

I concur. Clear the codes and see what comes back first. Then, address that and move on.

I have had The Boys from South of the Border in my truck for three different faults - shuttle valve switch electrical failure (addressed by the Option B solder joint bypass in Feb. 2011), a right rear sensor code and a left front sensor code. In a LARGE percentage of cases the sensor codes are due to problems with the electrical connectors back to the SLABS (computer) box, and NOT with the sensor itself or the hub.

So clear the codes, see what comes back first, and let us know. We're here to help. Good luck.

Yes thats true that the harness is the problem on a lot of rear ABS sensor codes. Rover sells or at least used to sell an overlay harness that would go from the ABS sensor connector. If the trans shifts correctly and the speedo works then you have some strange shit going on. Disco 2 uses an average of all 4 wheel speed sensors to calculate road speed. So if those things work it seems like ABS is the only module that can't see wheel speed.

 

[jastutte]

if the shuttle valve switch is testing bad, replace it. they can be had for under $30.00 new.

test the new unit before installing. if it tests good, install it and reset all the codes to see if any come back.

 

[Mcl1043]

Alright boys, I cleaned my ground up and found partial success. You’re right @discostew, those grounds were an absolute mess. Those 12 codes turned to 3. exactly what you had @mlnnc shuttle valve, right rear sensor and left front sensor. Can you expand on issues between the electrical connectors and the SLABS? Is it basic corrosion? How did you address it?

 

[Mcl1043]

if the shuttle valve switch is testing bad, replace it. they can be had for under $30.00 new.

test the new unit before installing. if it tests good, install it and reset all the codes to see if any come back.

I see they’re pretty inexpensive, I worry about quality at $30.00 only because the other times I’ve gone cheap on rover parts it’s come back to bite. Have you used a $30 one from ebay/does everything work alright?

 

[discostew]

Alright boys, I cleaned my ground up and found partial success. You’re right @discostew, those grounds were an absolute mess. Those 12 codes turned to 3. exactly what you had @mlnnc shuttle valve, right rear sensor and left front sensor. Can you expand on issues between the electrical connectors and the SLABS? Is it basic corrosion? How did you address it?

I'm not sure what the exact problem is with the circuit. It could be anything from terminal fretting to poor splices. If I remember correctly the overlay for the rear sensors goes all the way into the ecu. My money is on the front hub and bearing and the rear overlay harness. If you have meter you can check out those shuttle valve switches once you have them out. I'll bet you need the modification for the shuttle valve circuit. The stuff to do that mod will be the cheapest part of your repair. If you start looking for one of those overlay harness ask for just that. I would call it the overlay harness for rear wheel speed sensors. If they don't know what your asking for it's them not you.

 

[mlnnc]

One thing at a time.

The shuttle valve switch fault code may not indicate failed shuttle valve switches.

Weird, right?

The fault indicates something wrong in the circuit from the switches to the SLABS. The famous Option B bypasses a failed solder joint buried deep in the the modulator. When you remove the SVS pack you can easily test them with a multimeter and inspect for any sign of leaking brake fluid or failed insulation on the wires.

 

[jastutte]

the OP said he tested the SVS and it failed. assuming he tested it correctly, the failed tests indicates he needs at a minimum a new SVS.

he already did Option B. so, next step is to replace the SVS with new, clear the codes and drive the Rover to see what codes come back.

 

[mlnnc]

Whoops. I overlooked that he said he's already done Option B. He also says he tested the switches and they passed. I'd next double check the Option B wiring. That said, the SVS switches are not very expensive so maybe replace them anyway.

 

[boxster]

Special Ed, has a good post on the SVS repair.

 

[JohnnoK]

I had the 3 Amigos in permanent residence when I bought my Disco and they went away when I replaced the battery and made up a new earth lead from battery to the chassis.
I also fitted new terminal clamps at the same time, so earthing was a definite factor on my car.

 

[salvvia]

GET A BIGGER HAMMER

 

[JUKE179r]

what diagnostic tester are you using and what are the 3 fault codes you currently have?
I only ask as a Land Rover P0204 fault in the D2 RAVE manual is for “Injection circuit malfunction - cylinder 4 / Injector 4 open circuit” and not “ECU Ground or Reference Ground Fault.”
You could be barking up the wrong tree mate.

 

[Mcl1043]

what diagnostic tester are you using and what are the 3 fault codes you currently have?
I only ask as a Land Rover P0204 fault in the D2 RAVE manual is for “Injection circuit malfunction - cylinder 4 / Injector 4 open circuit” and not “ECU Ground or Reference Ground Fault.”
You could be barking up the wrong tree mate.

Odd - I was using a Carsoft LR reader. It turned out the grounds were fouls, so the code was correct. Odd that the reader contradicts the RAVE.

 

[Mcl1043]

Update - thanks for your help everybody. Like most, here I am posting what happened months later. Cleaning the grounds fixed most of the faults, a new shuttle valve fixed another one. Only two of the wheel sensors were actually bad. Someone said it perfectly on here... one thing at a time.

I was gearing up to change out the sensors when a tree came down and crunched old Ladybird - she was so tall it stopped the thing from crushing my moms brand new Buick (a heroes ending, gotta love it).

I bought a 04 4.6L D2 with a slipped sleeve for a grand, I'm about the drop this ones 4.0L in it, so I'll be reaching out for insight if anyone wants to come along for the ride. Thanks guys.

God bless.