Hello, yesterday on my wife's cx-9 the ABS/TCS and skidding car lights came on and are staying on. During my investigation I noticed that if I press the brake pedal down and hold it in hard it starts making a squealing sound and continues depressing, while sitting still in the driveway. I think that this is a sign of a bad/leaking brake booster. Would this also cause those lights to come on?

One other little bit of background. Last week I had the car lifted off of the ground to rotate the tires. I should note that this is a sport, FWD version, 2012. anyway, I have fairly new rotors, but I had swapped pads, and since then the front brakes have been vibrating a bit, I think because maybe there was some glazing from the previous pads, can't get rotors turned anywhere anymore, so I just put the car in drive with the held some 300 grit sandpaper against the rotors to remove any glazing. Could this have caused any issue with the abs/tcs system? I did notice when I put all of the wheels back on and drove car for the first time that the lights came on, but then after I had shut off and restarted they seemed to reset and go away, so I thought everything was ok.

Anyway, I'm wondering if the lights and squealing pedal are caused by the booster, or if something else may be going on also due to running with the wheels off of the ground, or due to the sanding dust??

Any advice is appreciated.

 

You need to get it scanned for fault codes.

 

yeah, I tried to read the codes with my black and decker scanner, but it did not pull anything. It worked for our honda and gm, but maybe not for Mazda. I will try another scanner.

 

So there were two issues. The wiring to one of my abs sensors was damaged. However it turns out that the brake booster was leaking also. I swapped it out this weekend. What a job, it is really buried in there. So now all of the lights are out but I have two new issues.

First, the pedal is quiet soft. My master cylinder seemed fine, no leaking, so I reused it. I did disconnect the two lines from cylinder to the abs unit. I bled all wheels with power bleeder till new fluid came out and no bubbles, still very soft. I then bled the cylinder by having my wife press the pedal while I loosened two lines I had removed. This helped some with the pedal feel. Definitely feels better when car is off. Better but still spongy while running. Maybe continuing to bleed will help, is there a better way to do this?

Second problem. I noticed my brake lights are on all the time. It turns out that the pedal, really the shaft from the booster, is not traveling out as far by about 1/4". When I push the pedal switch in it works as expected. I think the booster is against the firewall. Is there a way to adjust this?

 

Two more pieces of info.

When I pump the pedal with the car off it gets firm. With car running it doesn't.

The replacement booster I used was from Mazda dealer, number TDY1-43-80ZA
any help is appreciated. Really need to get this car back to my wife.

 

You need to carry out multiple ABS bleeds via relevant scan tool.

Also when you replace the booster you also need to replace the brake light switch. They normally **** themselves when you remove the booster.

 

The switch still seems to work. It just seems like the push rid isn't extending to the pe
dal enough. I'm not sure a new switch would help this

Is there a scan tool you recommend? Mine does not have this, And I'm not sure if all the ones that scan abs codes have the bleeding function.

Thanks for your help

 

I just ordered: FOXWELL NT630 Plus OBD2 Scanner ABS SRS Code Reader Automotive OBD II SRS Airbag Diagnostic and ABS Brake Bleed Scan Tool
From Amazon, will arrive tonight. Looks like it has what I need.

Thanks

 

Yeah! Finally done with it. Brakes feel better than ever. Scanner worked to get the air out. I was able to take the switch out and reset it. It has a racheting mechanism inside that adjusts after install and needs readjusted with a new booster. Of course a new switch would work too.

Someone else wrote this explanation of the switch reset, may help someone else: " Pull the switch out and take apart cover of main ratchet assembly. Reset the ratchet by twisting 90 degree and slide the black internal slide to max extension reward and reassemble. Remove the green electrical switch portion by turning 45 degrees and unplug the wire, inside of switch end of the plug is a small white plastic flat connected to switch arm.Catch the small slide with a small sharp point (has a small square in it for this purpose) and pull fully to rear (blade end) of the switch and release. This should allow the activation arm to fully pop out to max length, reassemble to ratchet assembly, install while pressing the brake pedal in and away from the switch. Release the brake lever and it will ratchet back to the to correct length."

Thanks again for your help.

 

I've done probably a dozen boosters, each time we replace the brake light switch.