Brake Pressure Sensors

[Leesy69]

Brilliant intel on this area people - thanks!

So my code disappeared really suddenly on the very next journey which I thought was odd. The guys who scanned the codes told me it was the sensors and then quoted me around £700 to have it fixed. But since then Ive done nothing and the codes have NOT reappeared.

So Im inclined to put it down to a glitch (maybe a slight voltage drop or something?) and wait to see if the warning message comes back.

The thing nagging at the back of my mind is that the mechanic gave me war and peace about how lots of things will be disabled if the pressure sensors have failed such as 4 wheel drive, abs, bending xenons, cd player etc.....

Cheers!

[swedishandgerman]

Originally Posted by Leesy69

Brilliant intel on this area people - thanks!

So my code disappeared really suddenly on the very next journey which I thought was odd. The guys who scanned the codes told me it was the sensors and then quoted me around £700 to have it fixed. But since then Ive done nothing and the codes have NOT reappeared.

So Im inclined to put it down to a glitch (maybe a slight voltage drop or something?) and wait to see if the warning message comes back.

The thing nagging at the back of my mind is that the mechanic gave me war and peace about how lots of things will be disabled if the pressure sensors have failed such as 4 wheel drive, abs, bending xenons, cd player etc.....

Cheers!

That's good then! Yes, the message only appears when the sensor or sensors are bad, then the message goes again. Mine started giving random messages about 6 months before giving up the ghost altogether. I have to say though that everything else appeared to be working properly including 4WD and ABS.

However, when the ABS rings were knackered, there were def other faults

[sreviz]

Originally Posted by Thassos

I did some checking into those pressure sensors, they put out a dc voltage relating to fluid pressure, and the bcm seems to compare the difference, so if your seeing the fault code it might not be complete failure of the sensor needing replacement. You can run a calibrate routine in vida that takes out small differences in the signal level that may fix things for some ppl. I did some long term logging of the outputs from them to get an idea how much they differed during use over time if anyone is interested !

Does any one knows how to calibrate the pressure sensors using Vida please.
I've cleaned the ABS pump connectors mo ths ago but abs warning light comes on intermenatly.
Checked it with Sensor 2 low signal and pressure sensors 1 and 2 outside permitted range.

Thank you.

[harveys]

what's the pressure difference between both sensors max is one bar when the pedal is not pressed .When pressed hard they should read the same ish within couple of bar.
to reset them in vida is the next screen after the test sensor screen .

[sreviz]

[IMG][/IMG]

Originally Posted by harveys

what's the pressure difference between both sensors max is one bar when the pedal is not pressed .When pressed hard they should read the same ish within couple of bar.
to reset them in vida is the next screen after the test sensor screen .

To be honest , I didn't check the difference using Vida. Just found this thread and trying my luck.
Iam not expertise in Vida. I use it clear codes and fi finding fault.
Could you please kindly let me know how to check it using Vida.



Below is the code I took out this morning but cleared it straight away. I think it wil come back again soon, it is an on going issue.

Thank you.

[harveys]

Originally Posted by sreviz

[IMG][/IMG]
To be honest , I didn't check the difference using Vida. Just found this thread and trying my luck.
Iam not expertise in Vida. I use it clear codes and fi finding fault.
Could you please kindly let me know how to check it using Vida.



Below is the code I took out this morning but cleared it straight away. I think it wil come back again soon, it is an on going issue.

Thank you.

Diagnostics/Vehicle communication/BCM/Advanced tab/open BCM + & -/Calibration then brake pressure sensors.

Hope you find it ok when I did mine 1 & 2 were giving strange reading so had to replace one.

[sreviz]

Originally Posted by harveys

Diagnostics/Vehicle communication/BCM/Advanced tab/open BCM + & -/Calibration then brake pressure sensors.

Hope you find it ok when I did mine 1 & 2 were giving strange reading so had to replace one.

Thank you for that procedure.

Mine showing 10 and 1 bar.

Could that low reading be only sensor fault or do I have leakage some where, which affects the pressure.

How to identify which one is sensor 1 and 2 please.

Thank you.[IMG][/IMG]

[Thassos]

The 1 bar reading is minus, so makes me think perhaps the sensor is disconnected or completely open circuit perhaps ?, have you tried cleaning the terminals up, also use a dvm to simply measure the voltage across each sensor, should be very similar, also with the brake pedal pressed..

if you want to confirm which sensor is showing the low reading just disconnect one and see which shows a different reading...if your using vida.

[sreviz]

Originally Posted by Thassos

The 1 bar reading is minus, so makes me think perhaps the sensor is disconnected or completely open circuit perhaps ?, have you tried cleaning the terminals up, also use a dvm to simply measure the voltage across each sensor, should be very similar, also with the brake pedal pressed..

if you want to confirm which sensor is showing the low reading just disconnect one and see which shows a different reading...if your using vida.

Thank youThassos.
I will clean the terminals with contact cleaner when I get home.
I have multimeter, I will check the voltage.
Biut Sorry to ask a dumb question .Do I have to check the voltage when the engine running or in key position 2. Also with brake pedals pressed at the same time.

Thank you.

[Thassos]

Try some fine wet & dry (its a grey coloured 'sandpaper'), but also use some folded into a spade shape to clean inside the push on connector (dont go too mad and remove the plating from either side).

You can measure the voltage with key in pos 2, to check if you measure any voltage, but to see a full pressure (and full voltage) reading have the engine running and get so someone to press the brake pedal, compare readings on both with (pedal released & pedal pressed) to see what signal the bcm is seeing. no worries no question is stupid, as you always learn something asking questions