DTC Troubleshooting: P0502 (17-8)

DTC P0502: VSS Circuit Malfunction

1. Test-drive the vehicle with the speed more than 20 km/h (12.5 mph).

1. Check the vehicle speed with the HDS.

Is the correct speed indicated?

YES | - | Intermittent failure, system is OK at this time. Check for poor connections or loose terminals at the VSS and the ECM.■
NO | - | Go to Step 3 .

1. Turn the ignition switch OFF.

1. Disconnect the VSS 3P connector.

1. Turn the ignition switch ON (II).

1. Measure voltage between VSS 3P connector terminal No. 1 and body ground.

Is there about 5 V?

YES | - | Go to Step 11 .
NO | - | Go to Step 7 .

1. Turn the ignition switch OFF, and wait 30 seconds.

1. Disconnect ECM connector No. 1 (96P).

1. Connect VSS 3P connector terminal No. 1 to body ground with a jumper wire.

1. Check for continuity between ECM connector No. 1 terminal No. 30 and body ground.

Is there continuity?

YES | - | Go to Step 29 .
NO | - | Repair open in the wire between the VSS and ECM connector No. 1 terminal No. 30, then go to Step 24 .

1. Measure voltage between VSS 3P connector terminal No. 2 and body ground.

Is there about 5 V?

YES | - | Go to Step 17 .
NO | - | Go to Step 12 .

1. Turn the ignition switch OFF, and wait 30 seconds.

1. Disconnect ECM connector No. 1 (96P).

1. Check for continuity between VSS 3P connector terminal No. 2 and body ground.

Is there continuity?

YES | - | Repair short in the wire between the VSS and ECM connector No. 1 terminal No. 84, then go to Step 24 .
NO | - | Go to Step 15 .

1. Connect VSS 3P connector terminal No. 2 to body ground with a jumper wire.

1. Check for continuity between ECM connector No. 1 terminal No. 84 and body ground.

Is there continuity?

YES | - | Go to Step 29 .
NO | - | Repair open in the wire between the VSS and ECM connector No. 1 terminal No. 84, then go to Step 24 .

1. Measure voltage between VSS 3P connector terminals No. 1 and No. 3.

Is there about 5 V?

YES | - | Go to Step 22 .
NO | - | Go to Step 18 .

1. Turn the ignition switch OFF, and wait 30 seconds.

1. Disconnect ECM connector No. 1 (96P).

1. Connect VSS 3P connector terminal No. 3 to body ground with a jumper wire.

1. Check for continuity between ECM connector No. 1 terminal No. 54 and body ground.

Is there continuity?

YES | - | Go to Step 29 .
NO | - | Repair open in the wire between the VSS and ECM connector No. 1 terminal No. 54, then go to Step 24 .

1. Turn the ignition switch OFF.

1. Replace the VSS.

1. Reconnect all connectors.

1. Turn the ignition switch ON (II).

1. Reset the ECM with the HDS.

1. Test-drive under these conditions:
   - Transmission in 3rd gear
   - Engine speed at 2,000 rpm (min −1 ) or more

1. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES | - | If DTC P0502 is indicated, check for poor connections or loose terminals at the VSS and the ECM, then go to Step 1 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | Troubleshooting is complete.■

1. Update the ECM if it does not have the latest software, or substitute a known-good ECM.

1. Test-drive under these conditions:
   - Transmission in 3rd gear
   - Engine speed at 2,000 rpm (min −1 ) or more

1. Check for Temporary DTCs or DTCs with the HDS.

Are any Temporary DTCs or DTCs indicated?

YES | - | If DTC P0502 is indicated, check for poor connections or loose terminals at the VSS and the ECM, then go to Step 1 . If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.
NO | - | If the ECM was updated, troubleshooting is complete. If the ECM was substituted, replace the original ECM. ■