Code B663, Cruise Speed Difference Between Actual And Set Too Large: Notes

Fig 1: Code B663, Cruise Speed Difference Between Actual and Set Too Large

Fig 2: Code B663, Cruise Speed Difference Between Actual and Set Too Large

Fig 3: Code B663, Schematic

Code B663 will set and disengage the cruise control if the actual speed is 30 MPH higher or lower than the set speed. This code is used to set upper and lower limits for operation of the cruise control system, and can be set under normal conditions if the operator accelerates, using the gas pedal, and goes 30 MPH over the set speed. If the operator experiences cruise drop out with this code set, but did not accelerate 30 MPH over the set speed, a mechanical problem is indicated.

1. BCM override value BS05 displays commanded servo position. The commanded range is normally 0-99%. If the servo will not go to full stroke, the vacuum supply, servo, or vacuum brake release circuit is leaking.
2. Checks to see if vacuum leak is due to brake release valve and circuit, or servo and source vacuum.
3. Checks to see if vacuum leak is due to vacuum source or servo.
4. Checks to see if fault is due to intermittent or slow vacuum leak.
5. Checks to see if fault is servo or brake vacuum release circuit.