I just got through a couple repairs on my 1998 Vanden Plas and thought I’d share my successes for whatever help they might bring anyone else in the future. Have had “Failsafe Engine Mode” alternating with “Stability Control” and “Traction Control” on my warning dash, as well as the ABS light, for months, and finally got around to fixing them. I hate warning lights, and boy does it feel good to have a clear dash now!

1. Warning: “Failsafe Engine Mode“ with rear brake lights always on as a symptom, and cruise control disabled. I tried WD40 on the Brake Switch, attached to the brake pedal, as suggested elsewhere, but it didn’t work (probably could have done more WD40). But I figured even if it worked it would have only been temporary, so other than the outrageous cost of a new brake switch, I didn’t mind just replacing the entire unit. And side by side, I could tell the old brake switch was bad because it sticks and catches when you press it in, unlike the new one.
Replacing the brake switch was obnoxious only because it’s a tight space, but it’s just one bolt holding it in, and one nut—that’s it. Comes right out, and goes right back in. DEFINITELY follow other advice on the forums of turning on the engine before starting to make depressing the brake pedal easy (you have to depress it all the way before removing and reinstalling the switch, or it’ll throw codes; and it’s much tighter if the brake pedal is in the way). And I cut a piece of 1x1 I had lying around to wedge the brake pedal all the way depressed, pressing against the underside of the front seat. I took under an hour to remove and reinstall the switch—I’m slow in general, but it is a tight spot to work and tricky. More able and well-equipped shadetree mechanics could have probably knocked it out in 10 or 15 minutes. Fired her up and no Engine Failsafe Mode, brake lights worked and cruise control was back!

2. The “three amigos.” I own a Land Rover Discovery 2 (I never pursued British cars intentionally, they just fell in my lap) and when ABS, Traction Control and Stability Control all come on, it’s notorious and called the Three Amigos. Infamous really. And I actually had it come on in my Jag and Land Rover at the exact same time!! It’s like two girls getting on the same cycle... I couldn’t believe the Jag was capable of the same electrical shenanigans, with the same manifestation of those three lights.
Anyway, enough of that. Robert’s video on YouTube was really great for showing the tools and specific bits needed (had to run out and get an E5 reverse torx bit), and his drilling technique for accessing the solder points on the ABS module was beautiful. I used those tips of his, and then plugged the holes I’d drilled with some gasket-maker silicone that was in the plastic cone tip from a previous job—it was already hardened in the caulking tip, so I cut the caulking tip off and pushed out the nicely shaped conical silicone plug, shaped it with snips to plug into the holes and taped over it with gorilla tape.

But my goodness, I did not want to have to remove the brake lines, take all the wheels off and rebleed the brakes afterward. So this guy showed how to do it without taking off the brake lines, and without kinking the lines, and it worked perfectly! I used a long 10 inch extension with a swivel adapter on my ratchet to get the E5 male torx screws out and in while leveraging up the brake lines (just a bit), and I also used a large pair of Vice grips, clamped the E5 bit in them, and was able to squeeze between the car frame and abs module to get to the lower two E5 bits, which are so tight my ratchet with the bit couldn’t fit. The large Vice grip holding the bit was perfect for breaking the initial sticking point on the torx bolts, and then I could hand unscrew them.
Got the ABS module out without having to disconnect the brake lines, repaired it in about ten minutes, and popped it back in.
One thing not in the videos, when plugging the big electrical connector back in to the ABS unit, you have to pull up on it to “unlock” it or it won’t slide on, then it just goes part ways on, then when you push down to lock it again it slides the rest of the way. I hadn’t seen a connector like that before, and it tripped me up for a bit.

And now my dash is free of warning lights and my traction control works again!

Good luck, and thanks for all the help from you guys.