Hello all, two years after correcting my ABS modulator and having no issues with it since, the 4 amigos poped up. (3 amigos + brake light) so I'm digging into possible causes. I checked the original fix to the modulator and found no issue, also checked the shuttle valve switches to no avail, and checked for 1000 ohms on each wheel sensor and they seamed fine however, I pulled the two front sensors out of their hubs to inspect and noticed something odd... one wheel has nice blue grease down on the teeth where the sensor reads, the other was dark and more oily looking like diff oil. Also, when I turn the hub by hand, I feel a concentric knocking. Could I just be feeling the teath of the ring and pinion of the diff as they turn? Or, is this an indicator of a wheel bearing going bad? I could not otherwise notice any of the typical bad wheel bearing indicators like any lateral play in the wheel.
Any thoughts?

 

Also, does anyone know a good way to test the ABS Mod motor? I want to rule out a bad motor.

 

The hand brake light on would lead me to think bad hub, worn pads, or stuck caliper. You need to get the codes read to narrow it down. The only way to clear the hand brake light is with the right software scan.

 

Thanks for the reply. Would an "ABS Amigo" be sufficient for reading/clearing the codes?

 

Not sure if low brake fluid level/bad level switch would cause this but that would be my first check, which you probably did but worth a mention

 

Yes, The Amigo would read and clear your codes.

I replaced my shuttle valve switches and did the option "B" repair two years ago. Within the past few months, the Amigos reappeared. After verifying my repair was still good, I checked voltages and continuity on all the wires and compared my readings against my friend's. Mine turned out to be the SLABS ECU itself.

Per RAVE, what will illuminate all 4 lights:
ABS seosnors
Inlet solenoid valves
Outlet solenoid valves
Reference earth (ground)
Return pump monitor
Return pump relay
Shuttle valve switches
SLABS ECU
Supply voltages

Definitely get a scanner or Amigo. I was lucky enough to have another Disco without codes to compare against.

 

Those will only illuminate 3 lights (amigos..) not the brake light as well.

Contrary to many posts in this thread, the red brake warning light will only illuminate due to low brake fluid, parking brake handle position, or (though very rare) an electronic brake force distribution system fault (noted from both personal experience and RAVE).

As far as testing modulator.. though this should be unrelated.. I recently realized that simply finding a big low speed hill and enabling HDC will be the easiest way to activate the ABS modulator.

However I'm pretty sure it wouldn't engage in this state..