Detroit Fault Codes SPN 84/FMI 3 – EPA10 – GHG14

12/12/2025

SPN 84/FMI 3 - EPA10 - GHG14

Vehicle Speed Sensor Open Circuit

NOTE: This SPN is broadcast to the Motor Control Module (MCM) via the Common Powertrain Controller (CPC).

SPN 84/FMI 3

Description	Vehicle Speed Sensor Circuit Failed High
Monitored Parameter	Vehicle Speed Sensor (VSS)
Typical Enabling Conditions	Always Enabled
Monitor Sequence	None
Execution Frequency	Always Enabled
Typical Duration	2 Seconds
Dash Lamps	MIL
Verification	Engine Idle (1 minute)

Possible causes:

1. Disconnect the VSS.

1.2. Measure the resistance between pin 13 of the CPC connector #3 (21–pin) and pin 1 of the VSS.

1.1. If the resistance is greater than 3 ohms, repair the open between pin 13 of the CPC connector #3 (21–pin) and pin 1 of the VSS.

2. If the resistance is less than 3 ohms, Go to step 3.

3. Measure the resistance between pin 14 of the CPC connector #3 (21–pin) and pin 2 of the VSS sensor.

3.1. If the resistance is greater than 3 ohms, repair the open wire between pin 14 of the CPC #3 connector (21–pin) and pin 2 of the VSS.

3.2. If the resistance is less than 3 ohms, Go to step 4.

4. Measure the resistance between pin 13 and 14 of the CPC connector #3 (21–pin).

4.1. If the resistance greater than 10K ohms, replace the VSS.

4.2. If the resistance is less than 10K ohms, repair the short in the harness between pins 13 and 14 of the CPC connector #3 (21–pin).

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