Code B660, Cruise Control Not In Drive: Diagnosis
This code was designed to prevent cruise control operation when vehicle is not in forward gear. If Code B127 is also set or there is complaint of flashing PRNDD21 display, refer to Code B127 diagnosis first. This code can be set if operator selects Neutral while cruise control is engaged. If operator describes this condition but did not move gear selector out of forward gears, check adjustment of PRNDD21, or for looseness in switch mounting or connections that could cause intermittent signals to BCM. Advise operator that shifting gears with cruise control engaged may cause this code to set.