DTC Troubleshooting: P0638 (40)

DTC P0638:  Throttle Actuator Control Range/Performance Problem

1.Turn the ignition switch ON (II).

2.Do the DTC CLEAR in the CLEAR MENU with the HDS.

3.Do the ETCS TEST in the INSPECTION MENU with the HDS.

4.Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS.

Is DTC P0638 indicated?


YES - Go to 5.


NO - Intermittent failure, system is OK at this time.Check for poor connections or loose terminals at the throttle body and at the ECM.n


5.Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS again.

Are DTC P0638, P1683 and P2109 indicated at the same time?


YES - Go to 22.


NO - Go to 6.


6.Turn the ignition switch OFF, and wait 10 seconds.

7.Connect the ECM test harness and the test pin box to the wire harness only, not to the ECM.

8.Check for continuity between test pin box terminals No. 122 and body ground.

Is there continuity?


YES - Go to 13.


NO - Go to 9.

9.Disconnect the throttle body 6P connector.

10.Check for continuity between test pin box terminal No. 122 and body ground.

Is there continuity?


YES - Repair short in the wire between the ECM connector No. 5 terminal No. 1 (test pin box terminal No. 122) and the throttle body, then go to 24.


NO - Go to 11.


11.Check for continuity between test pin box terminal No. 123 and body ground.

Is there continuity?


YES - Repair short in the wire between the ECM connector No. 5 terminal No. 2 (test pin box terminal No. 123) and the throttle body, then go to 24.


NO - Go to 12.


12.At the throttle body side, measure resistance between the throttle body 6P connector terminals No. 3 and No. 6.

 

Is there about 1.5 W?


YES - Go to 29.


NO - Go to 22.

13.Disconnect the throttle body 6P connector.

14.Check for continuity between test pin box terminals No. 122 and No. 123.

Is there continuity?


YES - Repair short in the wire between the ECM connector No. 5 terminal No. 1 (test pin box terminal No. 122) and the ECM connector No. 5 terminal No. 2 (test pin box terminal No. 123), then go to 24.


NO - Go to 15.


15.At the throttle body side, check for continuity between the throttle body 6P connector terminals No. 2 and No. 3.

 

Is there continuity?


YES - Go to 22.


NO - Go to 16.

16.At the throttle body side, measure resistance between the throttle body 6P connector terminals No. 3 and No. 6.

 

Is there about 1.5 W?


YES - Go to 17.


NO - Go to 22.


17.Connect the throttle body 6P connector terminal No. 6 to body ground with a jumper wire.

 

18.Check for continuity between test pin box terminal No. 122 and body ground.

Is there continuity?


YES - Go to 19.


NO - Repair open in the wire between the ECM connector No. 5 terminal No. 1 (test pin box terminal No. 122) and the throttle body, then go to 24.

19.Remove the jumper wire from the throttle body 6P connector.

20.Connect the throttle body 6P connector terminal No. 3 to body ground with a jumper wire.

 

21.Check for continuity between test pin box terminal No. 123 and body ground.

Is there continuity?


YES - Go to 29.


NO - Repair open in the wire between the ECM connector No. 5 terminal No. 2 (test pin box terminal No. 123) and the throttle body, then go to 24.

22.Turn the ignition switch OFF.

23.Replace the throttle body.

24.Reconnect all connectors.

25.Turn the ignition switch ON (II).

26.Do the ECM RESET in the CLEAR MENU with the HDS.

27.Do the ETCS learn procedure.

28.Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0638 is indicated, check for poor connections or loose terminals at the throttle actuator and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting.


NO - Troubleshooting is complete.n


29.Substitute a known-good ECM.

30.Check for Temporary DTCs or DTCs in the DTCs MENU with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - If DTC P0638 is indicated, check for poor connections or loose terminals at the throttle actuator and the ECM, then go to 1. If any other Temporary DTCs or DTCs are indicated, go to the indicated DTC troubleshooting.


NO - Replace the original ECM.