Cummins ISB4.5 CM2150 Fault Code: 241 PID: 84 SPN: 84 FMI: 2 Wheel-Based Vehicle Speed – Data Erratic, Intermittent, or Incorrect.

Circuit Description
The vehicle speed sensor senses the speed of the tailshaft gear on the vehicle’s transmission. This speed signal is then transmitted to the engine electronic control module (ECM) and converted into a vehicle speed.

Component Location
The vehicle speed sensor is located in the rear of the vehicle transmission. Refer to the OEM service manual for location.

Conditions for Running the Diagnostics
This diagnostic runs continuously when the vehicle is in motion.

Conditions for Setting the Fault Codes
The ECM detects a loss of vehicle speed when other engine operating conditions indicate that the vehicle could possibly be in motion.

Action Taken When the Fault Code is Active
-The ECM illuminates the amber CHECK ENGINE light immediately when the diagnostic runs and fails.
-The engine speed operating range is limited to the adjustable parameter “Maximum Engine Speed without VSS”.

Conditions for Clearing the Fault Code
-Start the engine and let it idle for 1 minute to validate the repair.
-The ECM will turn off the amber CHECK ENGINE light immediately after the ECM detects a valid engine speed signal from the vehicle speed sensor.
– The ECM will turn off the Malfunction Indicator Lamp (MIL) after three consecutive ignition cycles that the diagnostic runs and passes.
-This fault code and the MIL can also be cleared with INSITE™ electronic service tool.

Shop Talk
There are multiple types of vehicle speed sensors. Various types include magnetic pickup, data link, digital, and tachograph. Contact the OEM for the specific type installed on the vehicle.

This fault code is set active when the ECM loses a vehicle speed signal when other engine conditions indicate the vehicle is moving. The fault code can also become active if there is a series of clutch, service brake, or throttle movements, with no vehicle movement. The fault code is set inactive when the ECM receives a vehicle speed signal greater than zero.

Since the vehicle speed sensor is an OEM installed component, this troubleshooting procedure will not catch all malfunctions of the circuit due to components not under Cummins Inc. control. Sensor resistance values, data link speed sensors, and tachographs are not fully covered under this procedure.