Code B671, Cruise - Servo Position Sensor Circuit Problem: Notes

WARNING: This page is about a different car, the 1986 Oldsmobile Toronado and 1986 Buick Riviera. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Code B671, Cruise - Servo Position Sensor Circuit Problem

Fig 2: Code B671, Cruise - Servo Position Sensor Circuit

Fig 3: Code B671, Schematic

Code B671 will set if the ignition is on and the servo position sensor signal is below 3%. During the time the failure is present, the cruise control will be disengaged.

BCM data value BD70 displays servo position. The normal range is above 3%.
Checks to see if fault is due to short or open in the feedback circuits. Normal resistance across the feedback coil should be 15-30 ohms.
Checks to see if open circuit reading is due to servo or circuits.
Checks to see if problem is intermittent. BD70 will not go as low or as high as BS05 because of its mechanical limits of travel; however, it should never go below 3%.