DLC Circuit Troubleshooting

NOTE: Make sure the HDS and the DLC cable are in good operating condition.

1.Turn the ignition switch OFF.

2.Connect the HDS to the DLC.

NOTE: Make sure the HDS is properly connected to the DLC.

3.Turn the ignition switch ON (II), and turn on the HDS.

Does the HDS identify the vehicle?


YES - Go to 4.


NO - Go to 21.


4.Check for Temporary DTCs or DTCs in the PGM-FI system with the HDS.

Are any Temporary DTCs or DTCs indicated?


YES - Go to the indicated DTC's troubleshooting.n


NO - Go to 5.


5.Turn the ignition switch OFF.

6.Turn the ignition switch ON (II), and watch the SRS indicator.

Does the SRS indicator stay on?


YES - Go to the SRS system's general troubleshooting information.n


NO - Go to 7.

7.Turn the ignition switch OFF.

8.Turn the ignition switch ON (II), and watch the VSA indicator.

Does the VSA indicator stay on?


YES - Go to the VSA system's general troubleshooting information.n


NO - Go to 9.


9.Turn the ignition switch OFF.

10.Turn the ignition switch ON (II), and watch the EPS indicator.

Does the EPS indicator stay on?


YES - Go to the EPS system's general troubleshooting information.n


NO - Go to 11.

11.Turn the ignition switch OFF.

12.Turn the ignition switch ON (II), and watch the immobilizer indicator.

Does the immobilizer indicator stay on or flash?


YES - Go to the immobilizer system's troubleshooting.n


NO - Go to 13.


13.Do the gauge self- diagnostic function.

14.Check for B-CAN system DTCs without the HDS.

Are any B-CAN DTCs indicated?


YES - Go to the indicated DTC's troubleshooting.n


NO - Go to 15.


15.Turn the ignition switch OFF.

16.Disconnect the HDS from the DLC.

17.Check for continuity between DLC terminal No. 7 and body ground.

 

Is there 5 W or less?


YES - Go to 18.


NO - Go to 19.

18.Continue to check for continuity between DLC terminal No. 7 and body ground, while disconnecting these parts, one at a time:

  • SRS unit connector A (28P)
  • VSA modulator-control unit 46P connector
  • EPS control unit connector D (28P)
  • Immobilizer-keyless control unit 7P connector
  • Audio unit 17P connector
  • Under-dash fuse/relay box (Q) (16P) connector

Does continuity go away when one of the above components is disconnected?


YES - Replace the part that caused an open when it was disconnected.n


NO - Repair short in the wire between the DLC (K-line) and the VSA modulator-control unit, the SRS unit, the EPS control unit, the immobilizer-keyless control unit, the audio unit, or the under-dash fuse/relay box.n

19.Connect DLC terminal No. 7 to body ground with a jumper wire.

 

20.Check for continuity between body ground and these connector terminals:

Connector Terminal 
SRS unit A (28P) No. 24 (LT BLU) 
VSA modulator-control unit 46P No. 15 (LT BLU) 
EPS control unit D (28P) No. 17 (LT BLU) 
Immobilizer-keyless control unit 7P No. 5 (LT BLU) 
Audio unit 17P No. 6 (LT BLU) 
Under-dash fuse/relay box (Q) (16P) No. 8 (LT BLU) 


Is there continuity between the DLC terminal and each of the terminals in the chart?


YES - Replace the unit which cannot communicate with the HDS.n


NO - Repair open in the wire between the DLC (K-line) and the appropriate connector.n

21.Do the gauge self- diagnostic function.

22.Check for B-CAN system DTCs without the HDS.

Is DTC B1168, B1169 and/or B1178 indicated?


YES - Go to 35.


NO - Go to 23.


23.Turn the ignition switch OFF.

24.Disconnect the HDS from the DLC.

25.Measure voltage between DLC terminal No. 16 and body ground.

 

Is there battery voltage?


YES - Go to 26.


NO - Repair open in the wire between DLC terminal No. 16 and the No. 16 BACK UP (10 A) fuse in the under-hood fuse/relay box.n

26.Measure voltage between DLC terminals No. 4 and No. 16.

 

Is there battery voltage?


YES - Go to 27.


NO - Repair open in the wire between DLC terminal No. 4 and body ground (LHD: G502, RHD: G503).n


27.Connect the HDS to the DLC.

28.Remove the battery.

29.Disconnect ECM connector A (44P).

30.Disconnect the HDS from the DLC.

31.Connect DLC terminal No. 6 to body ground with a jumper wire.

 

32.Check for continuity between ECM connector terminal A36 and body ground.

 

Is there continuity?


YES - Go to 33.


NO - Repair open in the wire between the ECM (A36) and DLC terminal No. 6.n


33.Connect DLC terminal No. 14 to body ground with a jumper wire.

 

34.Check for continuity between ECM connector terminal A37 and body ground.

 

Is there continuity?


YES - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.n


NO - Repair open in the wire between the ECM (A37) and DLC terminal No. 14.n

35.Try to start the engine.

Does the engine start and idle smoothly?


YES - Go to F-CAN circuit troubleshooting.n


NO - Go to 36.


36.Turn the ignition switch OFF.

37.Check the No. 2 IG MAIN (50 A) fuse in the under-hood fuse/relay box.

Is the fuse OK?


YES - Repair open in the wire between the No. 2 IG MAIN (50 A) fuse and the ignition switch. If the wire is OK, go to 38.


NO - Repair short in the wire between the No. 2 IG MAIN (50 A) fuse and the under-hood fuse/relay box. Also replace the No. 2 IG MAIN (50 A) fuse.n

38.Check the No. 9 IGP (15 A) fuse in the under-hood fuse/relay box.

Is the fuse OK?


YES - Go to 43.


NO - Go to 39.


39.Remove the battery.

40.Disconnect ECM connector A (44P).

41.Check for continuity between ECM connector terminal A8 and body ground.

 

Is there continuity?


YES - Go to 42.


NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM. Also replace the No. 9 IGP (15 A) fuse.n

42.Continue to check for continuity between ECM connector terminal A8 and body ground, while disconnecting these parts, one at a time:

  • PGM-FI main relay 2 (FUEL PUMP)
  • Each injector 2P connector
  • CKP sensor 3P connector
  • CMP sensor 3P connector
  • Under-hood fuse/relay box 20P (white) connector

Does continuity go away when one of the above components is disconnected?


YES - Replace the part that caused an open when it was disconnected. Also replace the No. 9 IGP (15 A) fuse.n


NO - Repair short in the wire between the ECM (A8) and PGM-FI main relay 2 (FUEL PUMP), the injector, the CKP sensor, the CMP sensor, or the under-hood fuse/relay box. Also replace the No. 9 IGP (15 A) fuse.n


43.Check the No. 2 FUEL PUMP (15 A) fuse in the under-dash fuse/relay box.

Is the fuse OK?


YES - Go to 54.


NO - Go to 44.


44.Remove the battery.

45.Disconnect ECM connector C (44P).

46.Check for continuity between ECM connector terminal C36 and body ground.

 

Is there continuity?


YES - Go to 47.


NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM. Also replace the No. 2 FUEL PUMP (15 A) fuse.n


47.Remove PGM-FI main relay 2 (FUEL PUMP) (A) from the under-dash fuse/relay box.

 

48.Check for continuity between ECM connector terminal C36 and body ground.

 

Is there continuity?


YES - Repair open in the wire between the ECM (C9) and the No. 2 FUEL PUMP (15 A) fuse, between the No. 2 FUEL PUMP (15 A) fuse and PGM-FI main relay 2 (FUEL PUMP), or between the immobilizer control unit. Also replace the No. 2 FUEL PUMP (15 A) fuse.n


NO - Go to 49.


49.Remove the access panel from the floor.

50.Disconnect the fuel pump 4P connector.

51.Check for continuity between fuel pump 4P connector terminal No. 2 and body ground.

 

Is there continuity?


YES - Repair short in the wire between PGM-FI main relay 2 (FUEL PUMP) and the fuel pump. Also replace the No. 2 FUEL PUMP (15 A) fuse.n


NO - Go to 52.


52.Reinstall PGM-FI main relay 2 (FUEL PUMP) (A) to the under-dash fuse/relay box.

 

53.Check for continuity between fuel pump 4P connector terminal No. 2 and body ground.

 

Is there continuity?


YES - Replace PGM-FI main relay 2 (FUEL PUMP). Also replace the No. 2 FUEL PUMP (15 A) fuse.n


NO - Check the fuel pump, and replace it if necessary. Also replace the No. 2 FUEL PUMP (15 A) fuse.n


54.Remove the battery.

55.Disconnect ECM connector A (44P) and C (44P).

56.Connect a battery.

57.Turn the ignition switch ON (II).

58.Measure voltage between ECM connector terminal C36 and body ground.

 

Is there battery voltage?


YES - Go to 59.


NO - Repair open in the wire between the ECM (C36) and the No. 2 FUEL PUMP (15 A) fuse.n


59.Measure voltage between ECM connector terminal A6 and body ground.

 

Is there battery voltage?


YES - Go to 64.


NO - Go to 60.

60.Turn the ignition switch OFF.

61.Disconnect a battery.

62.Disconnect the under-hood fuse/relay box 20P (white) connector.

63.Check for continuity between ECM connector terminal A6 and under-hood fuse/relay box 20P (white) connector terminal No. 16.

 

Is there continuity?


YES -


NO - Repair open in the wire between the ECM (A6) and the under-hood fuse/relay box.n

64.Turn the ignition switch OFF.

65.Disconnect a battery.

66.Disconnect the under-hood fuse/relay box 20P (white) connector.

67.Check for continuity between ECM connector terminal A8 and under-hood fuse/relay box 20P (white) connector terminal No. 5.

 

Is there continuity?


YES - Go to 68.


NO - Repair open in the wire between the ECM (A6) and the under-hood fuse/relay box.n


68.Test PGM-FI main relay 1.

Is PGM-FI main relay 1 OK?


YES - Go to 69.


NO - Replace the under-hood fuse/relay box.n

69.Disconnect ECM connector B (44P).

70.Check for continuity between body ground and ECM connector terminals B1, B36, C2, C40, and C44 individually.

 

Is there continuity?


YES - Go to 71.


NO - Repair open in the wire between the ECM (B1, B36, C2, C40, C44) and G101,n

71.Check for continuity between ECM connector terminal C13 and body ground.

 

Is there continuity?


YES - Go to 72.


NO - Go to 73.


72.Continue to check for continuity between ECM connector terminal C13 and body ground, while disconnecting these parts, one at a time:

  • MAP sensor 3P connector
  • EOP sensor 3P connector
  • Output shaft (countershaft) speed sensor 3P connector

Does continuity go away when one of the above components is disconnected?


YES - Replace the part that caused an open when it was disconnected.n


NO - Repair short in the wire between the ECM (C13) and the MAP sensor, the EOP sensor, the output shaft (countershaft) speed sensor.n

73.Check for continuity between ECM connector terminal B18 and body ground.

 

Is there continuity?


YES - Go to 74.


NO - Go to 75.


74.Continue to check for continuity between ECM connector terminal B18 and body ground, while disconnecting these parts, one at a time:

  • IMT actuator 5P connector
  • EGR valve 6P connector

Does continuity go away when one of the above components is disconnected?


YES - Replace the part that caused an open when it was disconnected.n


NO - Repair short in the wire between the ECM (B18) and the IMT actuator, the EGR valve.n

75.Check for continuity between ECM connector terminal C12 and body ground.

 

Is there continuity?


YES - Go to 76.


NO - Go to 77.


76.Continue to check for continuity between ECM connector terminal C12 and body ground, while disconnecting the throttle body 6P connector.

Is there continuity?


YES - Repair short in the wire between the ECM (C12) and the throttle body.n


NO - Replace the throttle body.n

77.Check for continuity between ECM connector terminal A25 and body ground.

 

Is there continuity?


YES - Go to 78.


NO - Go to 79.


78.Continue to check for continuity between ECM connector terminal A25 and body ground, while disconnecting the APP sensor 6P connector.

Is there continuity?


YES - Repair short in the wire between the ECM (A25) and APP sensor A.n


NO - Replace the accelerator pedal module.n

79.Check for continuity between ECM connector terminal A24 and body ground.

 

Is there continuity?


YES - Go to 80.


NO - Go to 81.


80.Continue to check for continuity between ECM connector terminal A24 and body ground, while disconnecting the APP sensor 6P connector.

Is there continuity?


YES - Repair short in the wire between the ECM (A24) and APP sensor B.n


NO - Replace the accelerator pedal module.n

81.Check for continuity between ECM connector terminal A19 and body ground.

 

Is there continuity?


YES - Go to 82.


NO - Update the ECM if it does not have the latest software, or substitute a known-good ECM, then recheck. If the symptom/indication goes away with a known-good ECM, replace the original ECM.n


82.Continue to check for continuity between ECM connector terminal A19 and body ground, while disconnecting the A/C pressure sensor 3P connector.

Is there continuity?


YES - Repair short in the wire between the ECM (A19) and the A/C pressure sensor.n


NO - Replace the A/C pressure sensor.n