Brake Light
 

Hi guys:

On my 2006, the brake light on the dash comes on and stays on until you shut the car off. It doesn't turn on until the car starts moving. Then when it starts it may turn back on or not.

Its not the parking brake switch gone bad because when I lift the parking brake lever when driving I get the chime and the warning on the DIC.

Its also not low brake fluid as there is plenty of fluid and if the fluid is low you get a chime and warning on the DIC.

The brakes feel perfectly normal. The fluid is not going down (as if there was a leak)>

So what is this sensing?

Unlike MIL codes, there are no codes to help troubleshoot.

In the old days, there used to be a pressure switch in the distribution block that could sense unequal pressure between front and back.

Any ideas? My service manual is at home so I don't have access to the wiring diagrams right now.

I have had an ABS warning light for a few weeks. I know that the RF sensor is bad. I ordered a new hub and will install it soon. But the ABS light has been on for a few weeks without any brake warning light coming on. Could they be related?

Thanks
Steve

Related, yes. The fluid flow is controlled by the EBCM and the inputs are from the wheel speed sensors. The EBCM is basically a dynamic "distribution block".

Last time I checked the codes when the ABS light came on, I got the code for a bad right front wheel speed sensor. So I bought a front wheel hub with ABS sensor from Rock Auto and set it aside until I fixed the trans solenoid on the other HHR.

Meanwhile, I erased the ABS code to see if it returns and if its the same one. The ABS light came back on but I haven't checked the code the last few weeks, assuming its probably the same RF sensor.

Then the red BRAKE light started coming on and staying on, which is why I started this thread.

This morning I read the ABS codes stored.

Quite a few:

C0035 - LF Wheel Speed Sensor Circuit
C0899 - Control Module Power/Low Voltage
C0050 - RR Wheel Speed Sensor Circuit
C0045 - LR Wheel Speed Sensor Circuit
C0267 - The BlueDriver code reader says Low Brake Fluid indicated, but online search says this code means ABS pump motor circuit open.

Looks like a lot of stuff is going on. Since its unlikely all the sensors are bad at once, something is malfunctioning in the control system. I'll have to check to see if the connector at the EBCM came off or something.

Steve

My first guess is a bad battery or a loose wire. Note those are "circuit" faults. That reader doesn't show the hex digits? C0035-C0050 should have a suffix. Ignition voltage must be over 9.5V.

C0267 is low fluid.
C0899 means the ign voltage at the EBCM went below 9.0V. for 100msec.
Diagnostic is to compare ignition voltage at EBCM and battery terminal voltage; they should be within 1 V. If more than 1V, test the EBCM ground circuit for high resistance or replace the EBCM. That's a bit odd. Then it goes on to refer to "Engine Cranks Slowly".

I'm kind of thinking starter drawing too much because of that 100 msec thing.

I just went out to get a sub for lunch and both ways there and back, there was no BRAKE light lit up (for the first time in 2 days). The ABS light is still on.

Maybe its the low voltage that sets off the brake light. The car starts normally (very quickly) and has been that way. I haven't noticed any starting problems or extended or slow cranking.

The battery is less than a year old.

maybe I'll have to monitor the voltage on a logging voltmeter.

My Blue Driver scan tool can do real-time graphing of parameters, I'll have to see if it can log the voltage.

BTW, the low-brake-fluid warning comes on sometimes when the temperature drops to around 0 degrees F ( as it did last week, that's probably why the code is there). It has done this for many years. I think there is a TSB to replace the level sensor.

Steve

After writing down the codes that I previously mentioned, I erased the ABS codes to see what comes back.

The only code that was generated (as soon as the car started moving) was for the RF wheel speed sensor, which was the code I had for the last few weeks.

For now I am treating the previous rash of codes as an isolated incident and will keep an eye on it. No BRAKE light foir the last few days either.

The RF wheel speed sensor code is probably real, I have a new hub and will replace it this week.

Steve

This morning, as I rolled to a stop, the BRAKE light came on again. When I got to work, I read the codes. In addition to the "solid" RF brake sensor circuit fault I have had for the past few weeks, I got a LF wheel sensor circuit fault.

Based on this, I would guess that the ABS light comes on with any ABS fault, but if you get two or more different ABS codes, then the BRAKE light also comes on. Just a theory based on my observations.

I will have to check the connector at the EBCM to make sure it's connected fully and also that there is no corrosion on the connector pins.

Steve

You never did say what are the 2 suffix digits?

My code reader only shows Cxxxx. It doesn't show any extra suffix digits.

Steve