What causes GM code 24?

Failed vehicle speed sensor in the transmission Damaged speedometer cable or drive gear on cable models Open or shorted VSS wiring to the ECM Faulty instrument cluster buffer box on some trucks

How do I fix GM code 24?

Confirm the speedometer works since it shares the VSS signal on many models Retrieve codes with a paperclip across ALDL pins A and B after a short drive Inspect sensor wiring at the transmission for damage Test sensor output pulse while the drive wheels turn Replace the sensor only after wiring and drive gear check good

24 Vehicle Speed Sensor Error

Q: What does GM code 24 mean?

GM code 24 — Vehicle Speed Sensor Error. Applies to 1984-1995 GM cars and C/K trucks, Camaro, Corvette.

Make: GM (1982-1995)
Category: Powertrain - Transmission
Severity: Check Engine Light
Applies to: 1984-1995 GM cars and C/K trucks, Camaro, Corvette

How to read it

Code 24 reads as 2 flashes, pause, 4 flashes on the check-engine light. Jump terminals A and B on the ALDL connector with the key off, then turn the key on with the engine off and count the check-engine flashes.

What does GM code 24 mean?

24 — Vehicle Speed Sensor Error. This code sets when your vehicle computer detects vehicle speed sensor error.

Common causes of 24

Failed vehicle speed sensor in the transmission
Damaged speedometer cable or drive gear on cable models
Open or shorted VSS wiring to the ECM
Faulty instrument cluster buffer box on some trucks

How to fix 24

Confirm the speedometer works since it shares the VSS signal on many models
Retrieve codes with a paperclip across ALDL pins A and B after a short drive
Inspect sensor wiring at the transmission for damage
Test sensor output pulse while the drive wheels turn
Replace the sensor only after wiring and drive gear check good