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).

2.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.n


NO - Go to 3.


3.Turn the ignition switch OFF.

4.Disconnect the VSS 3P connector.

5.Turn the ignition switch ON (II).

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

 

Is there about 5 V?


YES - Go to 11.


NO - Go to 7.

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

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

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

 

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

 

Is there continuity?


YES - Go to 29.


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

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

 

Is there about 5 V?


YES - Go to 17.


NO - Go to 12.


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

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

14.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 24.


NO - Go to 15.

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

 

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

 

Is there continuity?


YES - Go to 29.


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

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

 

Is there about 5 V?


YES - Go to 22.


NO - Go to 18.


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

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

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

 

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

 

Is there continuity?


YES - Go to 29.


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


22.Turn the ignition switch OFF.

23.Replace the VSS.

24.Reconnect all connectors.

25.Turn the ignition switch ON (II).

26.Reset the ECM with the HDS.

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

28.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 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC's troubleshooting.


NO - Troubleshooting is complete.n

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

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

31.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 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.n