I was looking at this post and noticed that little jumper on the lower right of the diagnostics box. When I had my intake manifold off a couple weeks ago, I was cleaning up various stuff that had fallen down there over the years and found a little pin jumper thingie under the diagnostics box that fit some of the terminals perfectly, so I set it aside in my testing kit in case it's useful in the future.

But seeing that photo, I immediately recognized the mystery jumper. Sure enough, it fits those two terminals. I had to look up what WA and WB signify, since I've never done anything on the car requiring attention to those. I found that they're for the ABS (anti-lock braking) system, but couldn't find much more than that. WA = ABS ECU, WB = ABS relay.

https://www.clublexus.com/forums/ls4...ml#post8223544
https://www.clublexus.com/forums/rx-...ml#post6556359

My guess is, the jumper is supposed to be in place otherwise ABS is deactivated? Wouldn't one expect to get a CEL in that case? Actually, scratch that, I see the ABS codes are separate from the engine codes. That second link above (RX300 thread) sounds like it's just a matter of jumpering the Tc and E1 pins (as opposed to E1 and TE1 for engine CELs) with the WA-WB jumper removed.

I'm curious if the jumper was removed because something in the ABS system isn't working or if someone dropped it down there and couldn't recover it...

 

The ABS and Cruise lights blink constantly with Tc/E1 jumpered and the WA-WB jumper removed. Constant blinking on engine CEL means no codes stored, so that's encouraging assuming I followed the right procedure.

Anyone know whether having that WA-WB jumper removed disables the ABS system? I've yet to do any uber emergency breaking that would tell me if it's been working or not.

 

Found this:

http://www.justanswer.com/lexus/3q85...97-causes.html

That would seem to confirm that the WA-WB jumper is normally in place and is only removed to retrieve ABS codes.