Troubleshooting brake warning light (may have nicked a wire in harness) (1 Viewer)

[cryptyk]

I was running a wire through the 2007 LX470 firewall today via the driver's side engine bay grommet, into the cab above the brake pedal.
After starting the truck I noticed the brake light on the dash is solid on. I suspect I nicked a wire somehow but I'm not sure how I can verify that's the case vs. an actual brake problem (and I know how suddenly brake failures can happen in these rigs)
Any ideas on how I can differentiate between something like a failed emergency brake switch, master cylinder problem, or nicked wire in the harness (or some other reason the light is on)?

One other very odd thing: Because the light was on I played a bit with the brake pedal. If I'm parked and pump it hard about 15 times in a row, the brake warning buzzer comes on with a bunch of lights: vsc, vgrs, abs, and maint reqd. Then after a few seconds it all quiets down and goes back to normal. Not sure if that's new because I hadn't ever done that before.

 

[Bisho]

As I learned just yesterday, the brake light will also come on for low brake fluid.

With the key off, press the pedal ~40 times (till it pushes easily to the floor) and then check the reservoir level.

If it is low, look for the cause as well.

 

[2001LC]

It's normal and a test of brake alarm function, to activate with continuous pumping of brake peddle. ABS brakes, during normal use are never to be pumped, they're pressed and held. Pumping results in pressure loss, which booster pump can't keep up with. The pressure loss activates alarms.

 

[cryptyk]

It's normal and a test of brake alarm function, to activate with continuous pumping of brake peddle. ABS brakes, during normal use are never to be pumped, they're pressed and held. Pumping results in pressure loss, which booster pump can't keep up with. The pressure loss activates alarms.

Thanks. This solves part of my concern!

Just hooked up techstream and seeing a C1253: Hydro Booster Pump Motor Relay.
I think next step is to check continuity on that wire to see if I cut it while poking around in the grommet. Any advice on two points I can easily check between?

Just hooked up techstream and seeing a C1253: Hydro Booster Pump Motor Relay.
I think next step is to check continuity on that wire to see if I cut it while poking around in the grommet. Any advice on two points I can easily check between?

And here's a picture of the data from the ABS ecu if that helps?

Well I found the wire (R2+) that I must have clipped. Now it's just the frustrating work of trying to fix it when the cut is right inside the grommet.