Regal V6-191 3.1L (1991)
Vehicle Speed Sensor: Testing and Inspection
If any ECM Code is set, refer to Computers and Control Systems / Testing and Inspection.
If the symptom is the speedometer is not accurate, refer to TEST A: Speedometer Is Inaccurate below.
If the symptom is the speedometer or any speed-related function does not operate properly and ECM Code 24 is not set, refer to TEST B: Speed Signal
Test below.
If the symptom is not listed above perform both test A and test B below.
TEST A: SPEEDOMETER IS INACCURATE
Connect a scan tool to the ALDL connector. Drive the vehicle, or simulate vehicle speed by using J38522 Vehicle Speed Signal Generator. Observe
the Speedometer and compare it to the vehicle speed shown on the scan tool.
^
If both the Speedometer and scan tool display the same speed, check for correct tire size, tire inflation, ECM Mem-Cal and Vehicle Speed Sensor.
^
If scan tool and Speedometer do not display the same speed, replace the Instrument Cluster.
Test B: Speed Signal Test
TEST B: SPEED SIGNAL TEST
