Code B673, Cruise Vacuum Solenoid Circuit Problem: Notes

Fig 1: Code B673, Wiring Diagram (Reatta & Riviera) Cruise Vacuum Solenoid Circuit Problem

Fig 2: Code B673, Wiring Diagram (Toronado) Cruise Vacuum Solenoid Circuit Problem

The cruise control vent solenoid receives pulsed voltage signals from BCM to control the amount of time solenoid is energized. While time output is "HI", solenoid is energized and vacuum is not vented (or it is trapped) in servo. Code B673 will set if cruise is "ON", brake is not depressed and BCM output is "HI". Under either of these conditions, BCM will disable cruise control until BCM sees proper output signals. These determinations are made internal to BCM and may or may not affect "HI" or "LO" reading displayed during service mode. An output display of "LO" indicates circuit No. 403 should be de-energized (vent solenoid off) and an output display of "HI" indicates circuit No. 402 should be energized (vent solenoid on). Circuit No. 402 will be "HI" when solenoid is energized as BCM is providing voltage to vent solenoid which has its own full time ground. Circuit No. 402 will be "LO" when the solenoid is de-energized as the BCM removes voltage feed to solenoid.

1. BO02 cycles vacuum solenoid. The "HI" and "LO" refer to commanded state of voltage at BCM.
2. Checks to see if fault is due to servo or circuit.
3. Checks to see if fault is due to open ground circuit or control circuit, including servo solenoid.
4. Checks to see if fault is shorted servo or control circuit. If vacuum solenoid is shorted (less than 25 ohms) BCM replacement will also be necessary.