Vehicle Speed Sensor: Testing and Inspection

Vehicle Speed Sensor Schematic:

A faulty vehicle speed sensor will set code 33 in the on-board diagnostic system. Refer to the schematic diagram and test the sensor with the diagnostic chart.

Wire color code identification:

L: Blue
B: Black
Y: Yellow
G: Green
R: Red
W: White
Br: Brown
Lg: Light green
Gr: Gray

Vehicle Speed Sensor Diagnostic Chart:

VEHICLE SPEED SENSOR DIAGNOSTIC CHART

ECU Connectors:

Combination Meter Connectors:

CHECK ECU VOLTAGE

1. While slowly moving vehicle, measure voltage between ECU connector (F120)4 and ground.
2. Voltage should fluctuate above and below 2.5V.

CHECK HARNESS BETWEEN ECU AND SPEED SENSOR

1. With ignition "OFF," disconnect ECU and combination meter connectors.
2. Measure resistance between ECU connector (F120)4 and combination meter connector "a." [1] Resistance should be less than 1 Ohm.

3. Measure resistance between ECU connector and ground, and between combination meter connector and ground. Readings should be as follows:

Connector & terminal: Resistance:
(F120)4-Ground Infinite
"b" [1]-Ground Below 10 Ohms
(F119)1-Ground Below 10 Ohms
(F120)10-Ground Below 10 Ohms

CHECK SPEED SENSOR

1. Remove combination meter from instrument panel.
2. While slowly moving vehicle, measure resistance between combination meter terminals "a" and "b."[1] Tester pointer should deflect, indicating that the speed sensor switch is opening and closing.

[1] Refer to VEHICLE SPEED SENSOR DIAGNOSTIC CHART to determine which pins are "a" and "b."