Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DLC Circuit Troubleshooting (With Multipurpose Camera Unit) (2019 2020 2021)
DLC Circuit Troubleshooting
NOTE: If you suspect the HDS or the HDS DLC cable may be the source of the communication problem, verify that they are working properly by connecting them to a known-good, similar vehicle and system, and checking for communication problems.
- HDS communication check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Connect the HDS to the DLC.
NOTE: Make sure the HDS is properly connected to the DLC.
-3. Turn the vehicle to the ON mode, and turn on the HDS.
Does the HDS identify the vehicle?
YES
Go to step 2.
NO
Go to step 15.
- Determine possible failure area (PGM-FI system, other systems)
-1. Check for Pending or Confirmed DTCs with the HDS.
DTC Description Confirmed DTC Pending DTC Are any Pending or Confirmed DTCs indicated?
YES
Go to the indicated DTC's troubleshooting.
NO
If the HDS does not communicate with the PCM, go to step 3.
NO
If the HDS does not communicate with the SRS, go to step 5.
NO
If the HDS does not communicate with the VSA system, go to step 6.
NO
If the HDS does not communicate with the EPS system, go to step 7.
NO
If the HDS does not communicate with the IMMOBI (immobilizer) system, go to step 8.
NO
If the HDS does not communicate with the ONE-PUSH START system, go to step 9.
NO
If the HDS does not communicate with the BODY ELECTRICAL system, go to step 10.
NO
If the HDS does not communicate with the DRIVING SUPPORT system, go to step 11.
- Open wire check (F-CAN A_H line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Jump the SCS line with the HDS, and wait more than 1 minute.
-3. Disconnect the following connectors.
CAN gateway 16P connector PCM connector A (51P) -4. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected PCM connector A (51P): disconnected Test point 1 CAN gateway 16P connector (female terminals) No. 3: Test point 2 PCM connector A (51P) No. 3 Is there continuity?
YES
The F-CAN A_H wire is OK. Go to step 4.
NO
Repair an open in the F-CAN A_H wire between the PCM (A3) and the CAN gateway.
- Open wire check (F-CAN A_L line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected PCM connector A (51P): disconnected Test point 1 CAN gateway 16P connector (female terminals) No. 11: Test point 2 PCM connector A (51P) No. 4 Is there continuity?
YES
The F-CAN A_L wire is OK. Check for poor connections or loose terminals at the CAN gateway and the PCM. Go to the PCM power and ground circuit troubleshooting .
NO
Repair an open in the F-CAN A_L wire between the PCM (A4) and the CAN gateway.
- SRS check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Turn the vehicle to the ON mode, and watch the SRS indicator.
Does the SRS indicator come on and go off?
YES
The SRS is OK. Go to step 12.
NO
- VSA system check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Turn the vehicle to the ON mode, and watch the VSA indicator.
Does the VSA indicator come on and go off?
YES
The VSA system is OK. Go to step 12.
NO
- EPS system check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Start the engine, and watch the EPS indicator.
Does the EPS indicator come on and go off?
YES
The EPS system is OK. Go to step 12.
NO
Go to the EPS symptom troubleshooting for EPS indicator does not go off, and no DTCs are stored .
- Immobilizer system check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Turn the vehicle to the ON mode, and watch the immobilizer indicator.
Does the immobilizer indicator stay on or blinkΩ
YES
Go to the immobilizer system symptom troubleshooting information .
NO
The immobilizer system is OK. Go to step 12.
- Keyless access system check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Turn the vehicle to the ON mode, and watch the keyless access indicator and the immobilizer indicator.
Does the keyless access indicator stay on or the immobilizer indicator stay on or blinkΩ
YES
Go to the keyless access system symptom troubleshooting information .
NO
The keyless access system is OK. Go to step 12.
- Body electrical system check
-1. Do the gauge control module self-diagnostic function .
-2. Check the gauge display.
Is Error 2 indicated?
YES
Go to the indicated DTC's troubleshooting.
NO
The body electrical system is OK. Go to step 12.
- Driving support system check
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Turn the vehicle to the ON mode, and watch the ACC indicator, the CMBS indicator, the LKAS indicator, the RDM indicator, and the Auto High-Beam indicator.
Does the ACC indicator, the CMBS indicator, the LKAS indicator, the RDM indicator, and/or the Auto High-Beam indicator come on and go off?
YES
The driving support system is OK. Go to step 12.
NO
Go to the driving support system symptom troubleshooting; ACC , CMBS , LKAS , RDM , Auto High-Beam .
- Open wire check (K-LINE line or L-LINE line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the HDS from the DLC.
Disconnect the control unit(s) on the K-LINE or L-LINE that does not communicate.
NOTE: Before disconnecting the SRS unit connector A (39P), do the 12 volt battery terminal disconnection procedure and wait for at least 3 minutes.
K-LINE
- Immobilizer-keyless control unit 7P connector (without keyless access system)
- Audio unit connector A (24P) (without navigation)
- Audio-navigation unit connector A (24P) (with navigation)
- Keyless access control unit connector C (20P) (with keyless access system)
- Under-dash fuse/relay box connector D (24P)
- VSA modulator-control unit 21P connector
- ANC/active sound control unit 20P connector (with ANC/active sound control system)
L-LINE
- SRS unit connector A (39P)
- Keyless access control unit connector C (20P) (with keyless access system)
-4. Check for continuity between DLC (16P) No. 7 (K-LINE line) and these connector terminals, or DLC (16P) No. 15 (L-LINE line) and these connector terminals:
K-LINE
Connector Terminal Immobilizer-keyless control unit 7P connector (without keyless access system) No. 3 Audio unit connector A (24P) (without navigation) No. 12 Audio-navigation unit connector A (24P) (with navigation) No. 12 Keyless access control unit connector C (20P) (with keyless access system) No. 4 Under-dash fuse/relay box connector D (24P) No. 13 VSA modulator-control unit 21P connector No. 17 ANC/active sound control unit 20P connector (with ANC/active sound control system) No. 14 L-LINE
Connector Terminal SRS unit connector A (39P) (USA and Canada models) No. 33 Connector Terminal Keyless access control unit connector C (20P) (with keyless access system) No. 6 Is there continuity between the DLC and the terminals in the chart?
YES
Go to step 13.
NO
Repair an open in the wire between the DLC (K-LINE wire or L-LINE wire) and the appropriate connector.
- Determine possible failure area (short in K-LINE line or L-LINE line, others)
-1. Reconnect all connectors.
-2. If the 12 volt battery negative terminal is disconnected in step 12-3, do the 12 volt battery terminal reconnection procedure .
-3. Turn the vehicle to the ON mode.
-4. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode Test point 1 DLC (16P) (female terminals) No. 7 and No. 15: Test point 2 Body ground Is there any voltage?
YES
Go to step 15.
NO
Go to step 14.
- Shorted wire check (K-LINE line, L-LINE line):
Continue to measure the voltage between DLC (16P) No. 7 (K-LINE line) and body ground, or DLC (16P) No. 15 (L-LINE line) and body ground while disconnecting these parts, one at a time:
NOTE: Turn the vehicle to the OFF (LOCK) mode before disconnecting the connector, and turn the vehicle to the ON mode before measuring the voltage.
K-LINE
- Immobilizer-keyless control unit 7P connector (without keyless access system)
- Audio unit connector A (24P)
- Audio-navigation unit connector A (24P) (with navigation)
- Keyless access control unit connector C (20P) (with keyless access system)
- Under-dash fuse/relay box connector D (24P)
- VSA modulator-control unit 21P connector
- ANC/active sound control unit 20P connector (with ANC/active sound control system)
L-LINE
- SRS unit connector A (39P)
NOTE: Before disconnecting the SRS unit connector A (39P), do the 12 volt battery terminal disconnection procedure and wait for at least 3 minutes.
- Keyless access control unit connector C (20P) (with keyless access system)
Does voltage come back when one of the above components is disconnected?
YES
Replace the part that any voltage was detected when it was disconnected.
NO
Repair a short in the wire between DLC (16P) No. 7 (K-LINE) and the immobilizer-keyless control unit, the audio unit, the audio-navigation unit, the keyless access control unit, the under-dash fuse/relay box (MICU), the VSA modulator-control unit, the ANC/active sound control unit, or DLC (16P) No. 15 (L-LINE) and the SRS unit, the keyless access control unit.
- Body electrical system check
-1. Do the gauge control module self-diagnostic function .
-2. Check for gauge control module DTCs without the HDS.
Is DTC U0029 and/or U0100 indicated?
YES
Do the PCM power and ground circuit troubleshooting .
NO
Go to step 16.
- Open wire check (+B BACK UP line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Disconnect the HDS from the DLC.
-3. Measure the voltage between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Test point 1 DLC (16P) (female terminals) No. 16: Test point 2 Body ground Is there battery voltage?
YES
The +B BACK UP wire is OK. Go to step 17.
NO
Repair an open in the +B BACK UP wire between DLC (16P) No. 16 and the No. B21 fuse .
- Open wire check (GND line)
-1. Measure the voltage between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode Test point 1 DLC (16P) (female terminals) No. 4: Test point 2 DLC (16P) (female terminals) No. 16: Is there battery voltage?
YES
The GND wire is OK. Go to step 18.
NO
Repair an open in the GND wire between DLC (16P) No. 4 and G403.
- Open wire check (IG1 OPTION line)
-1. Disconnect the following connector.
CAN gateway 16P connector -2. Turn the vehicle to the ON mode.
-3. Measure the voltage between test points 1 and 2.
Test condition Vehicle ON mode CAN gateway 16P connector: disconnected Test point 1 CAN gateway 16P connector (female terminals) No. 9: Test point 2 Body ground Is there battery voltage?
YES
The IG1 OPTION wire is OK. Go to step 19.
NO
Repair an open in the IG1 OPTION wire between the CAN gateway and the No. C39 fuse .
- Open wire check (GND line)
-1. Turn the vehicle to the OFF (LOCK) mode.
-2. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected Test point 1 CAN gateway 16P connector (female terminals) No. 12: Test point 2 Body ground Is there continuity?
YES
The GND wire is OK. Go to step 20.
NO
Repair an open in the GND wire between the CAN gateway and G403.
- Open wire check (DIAG-CAN_H line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected Test point 1 CAN gateway 16P connector (female terminals) No. 2: Test point 2 DLC (16P) (female terminals) No. 6: Is there continuity?
YES
The DIAG-CAN_H wire is not open. Go to step 21.
NO
Repair an open in the DIAG-CAN_H wire between the CAN gateway and DLC (16P) No. 6.
- Open wire check (DIAG-CAN_L line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected Test point 1 CAN gateway 16P connector (female terminals) No. 10: Test point 2 DLC (16P) (female terminals) No. 14: Is there continuity?
YES
The DIAG-CAN_L wire is not open. Go to step 22.
NO
Repair an open in the DIAG-CAN_L wire between the CAN gateway and DLC (16P) No. 14.
- Shorted wire check (DIAG-CAN_H line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected Test point 1 DLC (16P) (female terminals) No. 6: Test point 2 Body ground Is there continuity?
YES
Repair a short in the DIAG-CAN_H wire between the CAN gateway and DLC (16P) No. 6.
NO
The DIAG-CAN_H wire is not shorted to ground. Go to step 23.
- Shorted wire check (DIAG-CAN_L line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected Test point 1 DLC (16P) (female terminals) No. 14: Test point 2 Body ground Is there continuity?
YES
Repair a short in the DIAG-CAN_L wire between the CAN gateway and DLC (16P) No. 14.
NO
The DIAG-CAN_L wire is not shorted to ground. Go to step 24.
- Shorted wire check (DIAG-CAN_H line to DIAG-CAN_L line)
-1. Check for continuity between test points 1 and 2.
Test condition Vehicle OFF (LOCK) mode CAN gateway 16P connector: disconnected Test point 1 DLC (16P) (female terminals) No. 6: Test point 2 DLC (16P) (female terminals) No. 14: Is there continuity?
YES
Repair a short in the DIAG-CAN_H wire to the DIAG-CAN_L wire between DLC (16P) No. 6 and No. 14.
NO
The DIAG-CAN_H wire and the DIAG-CAN_L wire are OK. Check for any authorized service information related to the DTCs or symptoms you are troubleshooting, or substitute a known-good CAN gateway , then recheck. If the HDS identifies the vehicle and the CAN gateway was substituted, replace the original CAN gateway .
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.