Vehicle Speed Sensor
1972 Dodge Challenger · 383ci V8
Sensor Type
mechanical-cable
Waveform Type
not-applicable
Location
Mechanical speedometer cable driven by gear on transmission output shaft, passenger side of 727 TorqueFlite automatic transmission or 4-speed manual
Pins
Unknown
Timebase
Not applicable
Voltage Scale
Not applicable
Trigger
Not applicable
Wiring
Not applicable - mechanical cable system only
Expected Voltage Range
At Idle
0V to 0V
At Higher RPM
0V to 0V
Expected Pattern
Mechanical rotation of flexible cable core inside housing, no electrical signal
Known-Good Waveform
The 1972 Challenger uses a mechanical speedometer cable system with no electronic speed sensor. The cable is driven by a gear on the transmission output shaft and directly rotates the speedometer head in the instrument cluster through a flexible inner cable core.
Common Failure Patterns
Speedometer needle bounces or fluctuates erratically
Cause: Dried or broken speedometer cable lubricant, kinked cable housing, or worn cable core
Speedometer does not register any speed
Cause: Broken speedometer cable core, failed drive gear at transmission, or seized speedometer head
Squealing noise from under dash correlating with vehicle speed
Cause: Dry speedometer cable needs lubrication or cable housing routing too tight causing binding
Diagnostic Tips
Disconnect cable at transmission and speedometer head to verify cable core rotates freely. Check transmission speedometer gear for worn teeth. Cable should be lubricated with graphite-based speedometer cable lubricant, not oil or grease which can migrate to speedometer head.
Related Diagnostic Trouble Codes
P0500P0501P0502P0503
Always confirm waveform data with your vehicle's OEM service manual before diagnosing.
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