SPN 84 - FMI 2 (Fault Code 241)

Vehicle Speed Sensor Circuit - Data Erratic, Intermittent or Incorrect

Vehicle Speed Sensor Circuit

Fault Code: 241
PID(P), SID(S): P084
SPN: 84
FMI: 2/2
Lamp: Amber

REASON: Vehicle Speed Sensor Circuit - Data Erratic, Intermittent or Incorrect. The ECM lost the vehicle speed signal.

EFFECT: Engine speed limited to Maximum Engine Speed without VSS parameter value. Cruise control, Gear-Down Protection, and Road Speed Governor will not work.

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.

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

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

Read More:
SPN 644 - FMI 2 (Fault Code 237)
SPN 661 - FMI 4 (Fault Code 238)


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