Acura TSX / Honda Accord CL. Manual - part 638

Fig. 16: Measuring Voltage Between VTEC Oil Pressure Switch Terminal No. 1 & Body 
Ground 

11. Measure voltage between ECM/PCM connector terminal B11 and body ground. 

Is there battery voltage? 

YES: Repair open in the wire between the ECM/PCM (B11) and the VTEC oil pressure 
switch, then go to step 12.  

NO: Go to step 19 .  

 

2004 Acura TSX 

2004 ENGINE PERFORMANCE VTEC/VTC - TSX

  

 

Fig. 17: Measuring Voltage Between ECM/PCM Connector Terminal B11 & Body Ground 

12. Turn the ignition switch OFF.  

13. Reconnect the VTEC oil pressure switch 2P connector.  

14. Turn the ignition switch ON (II).  

15. Reset the ECM/PCM with the HDS.  

16. Do the ECM/PCM idle learn procedure (see ECM/PCM IDLE LEARN PROCEDURE ).  

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

Are any Temporary DTCs or DTCs indicated? 

YES: If DTC P2647 is indicated, check for poor connections or loose terminals at the VTEC 
oil pressure switch and the ECM/PCM, then go to step 1 . If any other Temporary DTCs or 

 

2004 Acura TSX 

2004 ENGINE PERFORMANCE VTEC/VTC - TSX

  

 

DTCs are indicated, go to the indicated DTC troubleshooting. 

NO: Go to step 18.  

18. Monitor the OBD STATUS for DTC P2647 in the DTCs MENU with the HDS. 

Does the screen indicate PASSED? 

YES: Troubleshooting is complete.  

NO: If the screen indicates FAILED, then go to step 1 and recheck. If the screen indicates 
NOT COMPLETED, go to step 16 and recheck.  

19. Update the ECM/PCM if it does not have the latest software, or substitute a known-good ECM/PCM (see 

ECM/PCM UPDATING AND SUBSTITUTION FOR TESTING ).  

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

Are any Temporary DTCs or DTCs indicated? 

YES: If DTC P2647 is indicated, check for poor connections or loose terminals at the VTEC 
oil pressure switch and the ECM/PCM, then go to step 1 . If any other Temporary DTCs or 
DTCs are indicated, go to the indicated DTC troubleshooting.  

NO: If the ECM/PCM was updated, troubleshooting is complete. If the ECM/PCM was 
substituted, replace the original ECM/PCM (see HOW TO REMOVE THE ECM/PCM 
FOR TESTING ).  

DTC P2648: VTEC SOLENOID VALVE CIRCUIT LOW VOLTAGE 

1. Turn the ignition switch ON (II).  

2. Clear the DTC with the HDS.  

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

Is the result OK? 

YES: Intermittent failure, system is OK at this time. Check for poor connections or loose 
terminals at the VTEC solenoid valve and the ECM/PCM.  

NO: Go to step 4.  

4. Turn the ignition switch OFF.  

5. Disconnect the VTEC solenoid valve 2P connector.  

6. Measure resistance between VTEC solenoid valve 2P connector terminals No. 1 and No. 2. 

Is there 14-30 ohm? 

YES: Go to step 7.  

NO: Go to step 10 .  

 

2004 Acura TSX 

2004 ENGINE PERFORMANCE VTEC/VTC - TSX

  

 

Fig. 18: Measuring Resistance Between VTEC Solenoid Valve 2P Connector Terminals No. 1 
& No. 2 

7. Jump the SCS line with the HDS.  

8. Disconnect ECM/PCM connector B (24P).  

9. Check for continuity between ECM/PCM connector terminal B6 and body ground. 

Is there continuity? 

YES: Repair short in the wire between the ECM/PCM (B6) and the VTEC solenoid valve, 
then go to step 11 .  

NO: Go to step 18 .  

 

2004 Acura TSX 

2004 ENGINE PERFORMANCE VTEC/VTC - TSX