Detroit DD15 GHG14 (2014-16) Fault Code: SPN 1624 FMI 19 (CPC) Tachograph Vehicle Speed Signal is Erratic

NOTE: Please see the step by step troubleshooting procedures for this specific code.

NOTE: If any battery voltage codes present, first those first. If code 625-9 active, fix that before proceding as well.

PROBABLE CAUSES:
1. CPC recently programmed incorrectly.
2. Another computer on the truck is the cause of the problems (ABS, Transmission, etc…).