Mccall - what should the reading be for the output voltage at the bumper? If I use a multimeter, I get fluctuations at full output from 3 to 7 volts. I would think I should see at least 12 volts with the gain turned all the way up and the trolley brake maxed.I'm gonna assume that you made a tester for the ITBC output (if you didn't, quit making excuses), SO...........
The Master Cylinder Pressure Sensor operates from a 5V reference generated within the EBCM. It also has a ground and an output.
Pin A (Ye/Bk tracer)....... Ground (referenced, not chassis)
Pin B (Gray)..................5 Volt reference
Pin C (Orange)..............Sensor output
With the pedal not depressed, key on, measure across B to A with a digital voltmeter. Voltage should be around 1 volt. Have a helper depress, slowly, the brake pedal all the way to full apply, and the voltage should rise to nearly 5 volts. Failure to change voltage will indicate a faulty sensor.
BTW, resistance between the blue and white wires on the trailer must be 2.0 Ohms or less. One magnet will not allow the system to operate under pedal braking BUT it will respond to the manual apply.
What does everyone else get?