Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
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HOMESERVICE MANUALSCHEVROLET1993SUBURBAN 3/4 TON 2WD V8-454 7.4LREPAIR AND DIAGNOSISPOWERTRAIN MANAGEMENTCOMPUTERS AND CONTROL SYSTEMSVEHICLE SPEED SENSORTESTING AND INSPECTION
1993 Chevrolet Suburban 3/4 Ton 2WD V8-454 7.4L
Vehicle Speed Sensor: Testing and Inspection
1993 Chevrolet Suburban 3/4 Ton 2WD V8-454 7.4LSECTION Testing and Inspection
VSS Check:
VSS Circuit:
CIRCUIT DESCRIPTION:
The Vehicle Speed Sensor (VSS) circuit consists of a magnetic induction type sensor, vehicle speed sensor buffer module, and wiring. Gear teeth pressed on the outside diameter of the output carrier assembly induce an alternating current in the sensor. This current is transmitted to the buffer module where it is passed on to the PCM/TCM. The buffer module compensates for various axle ratios and converts the signal to a square wave for use by the speedometer, cruise control and antilock brake system.
TEST DESCRIPTION:
Number(s) below refer to circled number(s) on the diagnostic chart.
1. This test checks the vehicle speed sensor signal to the PCM/TCM.
2. This test checks the vehicle speed sensor signal to the buffer module.
3. This test checks the vehicle speed sensor signal.
DIAGNOSTIC AIDS:
- Check all connections at the transmission pass-thru connector.
- If the input sensor is not functioning at start up, it will cause the output sensor to display zero.
- While DTC 24 is set the scan tool will display an RPM derived from input speed.
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.