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I have the Brake light intermittently illumining on acceleration and then slip light. In the past on my previous G37 it meant the pads were getting bad or brake fluid was low.
Just had a brake inspection and brakes are good. Brake fluid was a tad low it was topped off. Mechanic said brake light is illuminating due to a bad Brake Fluid Sensor.
Mechanic said the entire Master Cylinder needs to be replaced to fix.
Quoted me $735 with parts and labor with the bleed and fluid flush.
I see the sensor itself available for around $30. Is it not possible to just replace the Brake Fluid Sensor itself without having to do the entire Master Cylinder?
In looking at various parts diagrams and images, you should be able to slide out the old switch and pop in a new one:
The only potential issue would be seals/ o-rings and making sure they are intact.
I do not know if the switch can be replaced with the master still connected to the car. There is VERY little space to work in that area and none of the factory manuals state any methods to remove just the switch. Keep in mind that brake fluid will destroy painted areas if spilled.
Either way, I think replacing the whole master just for the switch is overkill and not necessary.
In looking at various parts diagrams and images, you should be able to slide out the old switch and pop in a new one:
The only potential issue would be seals/ o-rings and making sure they are intact.
I do not know if the switch can be replaced with the master still connected to the car. There is VERY little space to work in that area and none of the factory manuals state any methods to remove just the switch. Keep in mind that brake fluid will destroy painted areas if spilled.
Either way, I think replacing the whole master just for the switch is overkill and not necessary.
Thank You for your very informative reply. I have scoured the internet for someone else who may have had this part replaced and literally find Zero. Very odd, gotta get another opinion from a different mechanic I know.
Excellent find, beefychicken! If that is the case, then replacing the switch should be simple and definitely NOT worthy of replacing the entire master as OP's mechanic wanted to do!
Seems to me that these "no contact" switches can not be that reliable, but what do I know...
Last edited by ILM-NC G37S; Oct 20, 2022 at 02:38 PM.
Drove around with Brake Light / Slip Illuminating intermittingly for a week. Popped in to my regular mechanic. He thought the fluid was still a tad low and added a small amount and then felt the sensor and made sure it was seated properly.
The warning lights went off and after solid 3 weeks have not returned. No Charge. To me it appeared the fluid level was adequate, I must have been wrong.
This sensor either cuts or adds ground to the system when it's low so a quick test to determine if its your brake sensor is to just jump the connector and the light should turn off.
