DTC Troubleshooting: P0503 (17)
DTC P0503:
 Output Shaft (Countershaft) Speed Sensor Signal Malfunction
NOTE: Before you troubleshoot, record all freeze data and review the general troubleshooting information.
  1. Clear the DTC with the HDS.
  1. Start the engine, then let it idle.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0503 indicated?
YES -
Go to Step 6 .
NO -
Go to Step 4 .
  1. Test-drive the vehicle for several minutes in the range of the recorded freeze data.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0503 indicated?
YES -
Go to Step 6 .
NO -
Intermittent failure, the system is OK at this time. Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM.■
  1. Reset the ECM with the HDS.
  1. Check for poor or loose connections and terminals at the following:
    • Output shaft (countershaft) speed sensor
    • ECM
    • Engine ground
    • Body ground
Are the connections and terminals OK?
YES -
Go to Step 8 .
NO -
Repair the connectors or terminals, then go to Step 9 .
  1. Turn the ignition switch ON (II).
  1. Reset the ECM with the HDS.
  1. Start the engine, then let it idle.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0503 indicated?
YES -
Go to Step 15 .
NO -
Go to Step 13 .
  1. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
    • ENGINE SPEED
    • VSS
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0503 indicated?
YES -
Go to Step 15 .
NO -
Troubleshooting is complete. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■
  1. Start the engine, then let it idle.
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0503 indicated?
YES -
Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM. If the ECM was updated, substitute a known-good ECM, then go to Step 16 . If the ECM was substituted, go to Step 1 .
NO -
Go to Step 18 .
  1. Test-drive the vehicle for several minutes in the range of these recorded freeze data parameters:
    • ENGINE SPEED
    • VSS
  1. Check for Temporary DTCs or DTCs with the HDS.
Is DTC P0503 indicated?
YES -
Check for poor connections or loose terminals at the output shaft (countershaft) speed sensor and the ECM. If the ECM was updated, substitute a known-good ECM, then go to Step 18 . If the ECM was substituted, go to Step 1 .
NO -
If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.■