puzzeled by brake switch status
Posted: Thu Aug 29, 2019 10:55 am
looking for some help here....still.....
I am trying to get this brake pedal position switch to work properly. Basically, the current setup works when the KOEO, but once the engine starts, I get nothing to register. It remains in the same state after start as it was just prior to start. log is attached.
Also attached are the wiring diagrams for the 2014 Caprice PPV, trying to understand what I am doing wrong, or if the ECM changes source data to output the state of the brake pedal.
At present, I have wired the dual brake switch (NO and NC switch) so that the NC portion connects the X1 pin 9 to ground. Once the brake is applied, that circuit is opened. With and without a 1K resistor, this wiring works fine and registers the state change on the log. Once the engine is running, this state does not change...whether I apply ground or 12V....it does not change. This essentially mimics the second wiring diagram.
My harness also does not have wires for a brake position sensor, nor does the brake pedal. This is the first photo. I can make something to mimic this wiring, but a perminent install will be challenging. My idea here would be to use the NC switch to apply a single resistanced 5v signal to pin 26. But doing so would mean eliminating the current setup.
My questions:
1) what does the e38 do with this data when in operation? if it thinks the brake is always on or off, will that change the operation somehow?
2) should I even make an issue of this? Afterall, the TCC is working as advertised.
3) does the e38 computer change source data for the brake position once the engine starts?
4) can/should I repin my harness to reflect a false brake position switch using a singal reistance and 5v signal?
thanks for the time!
~Ryan
Charleston, SC
I am trying to get this brake pedal position switch to work properly. Basically, the current setup works when the KOEO, but once the engine starts, I get nothing to register. It remains in the same state after start as it was just prior to start. log is attached.
Also attached are the wiring diagrams for the 2014 Caprice PPV, trying to understand what I am doing wrong, or if the ECM changes source data to output the state of the brake pedal.
At present, I have wired the dual brake switch (NO and NC switch) so that the NC portion connects the X1 pin 9 to ground. Once the brake is applied, that circuit is opened. With and without a 1K resistor, this wiring works fine and registers the state change on the log. Once the engine is running, this state does not change...whether I apply ground or 12V....it does not change. This essentially mimics the second wiring diagram.
My harness also does not have wires for a brake position sensor, nor does the brake pedal. This is the first photo. I can make something to mimic this wiring, but a perminent install will be challenging. My idea here would be to use the NC switch to apply a single resistanced 5v signal to pin 26. But doing so would mean eliminating the current setup.
My questions:
1) what does the e38 do with this data when in operation? if it thinks the brake is always on or off, will that change the operation somehow?
2) should I even make an issue of this? Afterall, the TCC is working as advertised.
3) does the e38 computer change source data for the brake position once the engine starts?
4) can/should I repin my harness to reflect a false brake position switch using a singal reistance and 5v signal?
thanks for the time!
~Ryan
Charleston, SC