I have recently had an issue with the brake warning light coming for 15 seconds or so after navigating a freeway cloverleaf etc. It doesn't come on under any other circumstances. Of course, this sounds like a low brake fluid issue (fluid moves to one side of the reservoir in the corner, causing the sensor to report the fluid is low). However, I have checked the fluid level in the reservoir, and it is very near the full line. I see no external evidence of leakage anywhere (not surprising since the fluid level in the reservoir isn't low), and the brakes work exactly as they always have. I know the brake light can indicate problems with the traction battery (brand new, in my case), but that doesn't seem to be likely considering the consistently intermittent nature of the warning light illumination. Does the brake warning light monitor anything else other than certain traction battery issues, brake fluid level, and the parking light being on? Is the sensor for the brake fluid level a simple float like I have seen on other vehicles? If so, has anyone ever heard of the float sticking? Any other ideas? Thanks,
Interesting! Is the consistent intermittence consistent enough that you can make the light come on by taking a certain corner at a certain speed? If so, you might temporarily unplug the float switch. (Might need an ohmmeter to check whether the switch is normally open or normally closed when the fluid level is right. If NO, just leave the plug dangling, if NC, jumper the harness plug to simulate the closed switch.) Then go for a drive and see whether you can still make the light come on. If it still comes on, the problem is something other than fluid level sensing. Be sure to remove any jumper and plug the switch back in when done. But before you fuss with any of that, just read out the brake codes. Jumper the TC and CG pins (13 and 4) at the diagnostic connector, turn the key ON (not all the way to READY), and watch the brake light blink. Steady fast blink means no codes to report. Otherwise, count blinks for two-digit codes (blink - pause - blink blink would be 12) and report them here. There can be more than one two-digit code - if so they'll be separated by longer pauses. Another thing that happens going around corners is wheels turn at different speeds. There are speed sensors at all four wheels, and the codes you get might indicate something fishy there. Let's see. -Chap
I'll try reading the brake codes. Is it obvious which pins are which on the connector? It pretty much always comes on while getting onto the freeway at the beginning of my daily commute. I'll try pulling the plug from the float and seeing if the light still comes on. If the brake warning light comes on immediately when I unplug the float switch, that would mean I need to jumper the connector, correct?
I have had the same symptom for over a year now. Never considered it more than a nuscence. Glad you're motivating us to take another look. Bob Wilson
I tried disconnecting the wires to the fluid reservoir and the brake warning light comes on, so the switch is normally closed. So I will try jumpering the connector and seeif the warning light comes on in the usual situations.
Sounds good. Did you check for any codes first? (I'm not sure if it logs a code for fluid level, but if it does you might have one now, just from unplugging the connector.) -Chap
Well, I feel a little silly. I guess almost full, isn't full enough. When I checked the brake fluid level, it was only about 1/8" below the full line, so I thought that was "full enough." However, I guess that is low enough to set off the warning light when cornering. I filled it right up to the line, and now the light isn't coming on any more. Because the reservoir is so large, that 1/8" I put in was actually about 1/2 pint of brake fluid.
