Code EI71 - Cruise Control/VCC Brake Circuit: Notes
The VCC brake switch is normally closed and opens when brake pedal is depressed. The VCC brake switch serves 3 functions: brake switch supplies power to VCC solenoid and cruise vacuum valve, and a brake "ON/OFF" indication to ECM.
The VCC brake switch receives 12 volts from 15A Ignition-1 fuse on circuit No. 39, and sends the 12-volt signal to ECM and VCC solenoid on circuit No. 420. When brake is depressed, switch opens and circuit No. 420 voltage is read by ECM as zero (0) volts.
On diagnostic display, "Hi" is a closed switch (not braking) while "Lo" is an open switch (braking pedal depressed). The ECM uses VCC brake input to determine braking status for VCC apply and release, as will as a test condition for many codes.
NOTE:
The following step numbers refer to the numbers in the accompanying flow chart(s).
- At key on, braking should have 12 volts on both sides of VCC brake switch. Test light to ground should light, if either pin on brake switch connector is backprobed.
- Light on one side means that brake switch is open as if brake pedal were depressed.
- Light on circuit No. 420 with pedal depressed means that brake switch never opens.
- Remove and replace ECM "A/B" connector and ensure that it is latched.