Lexus IS250 IS220d GSE20 ALE20 - CAN COMMUNICATION
CHECK FOR SHORT TO B+ IN CAN BUS LINE
CHECK FOR SHORT TO B+ IN CAN BUS LINE
CHECK FOR SHORT TO B+ IN CAN BUS LINE
CAN COMMUNICATION SYSTEM (for LHD) - Short to B+ in CAN Bus Line
DESCRIPTION
A short to B+ is suspected in the CAN bus line when the resistance between terminals 6 (CANH) and 16 (BAT), or terminals 14 (CANL) and 16 (BAT) of the DLC3 is below 1 MΩ.
| Symptom | Trouble Area |
| The resistance between terminals 6 (CANH) and 16 (BAT), or terminals 14 (CANL) and 16 (BAT) of the DLC3 is below 1 MΩ. | Short to B+ in CAN bus line Skid control ECU Steering angle sensor Yaw rate sensor ECM Gateway ECU Distance control ECU Seat belt control ECU Power steering ECU Center airbag sensor Television camera ECU |
WIRING DIAGRAM
INSPECTION PROCEDURE
| 1.CHECK FOR SHORT TO B+ IN CAN BUS LINE |
Turn the engine switch off.
Disconnect the DLC3 branch line connector (J8) from the CAN LH J/C B side (without earth terminal) .
- NOTICE:
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Condition Specified Value J21-6 (CANH) - J21-16 (BAT) Engine switch off 1 MΩ or higher J21-14 (CANL) - J21-16 (BAT) Engine switch off 1 MΩ or higher
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| OK | |
| 2.RECONNECT CONNECTOR |
Reconnect the DLC3 branch line connector (J8) to the CAN LH J/C B side (without earth terminal) .
| NEXT | |
| 3.CHECK FOR SHORT TO B+ IN CAN BUS LINE |
Disconnect connectors from the CAN LH J/C or CAN RH J/C one at a time.
- HINT:
- Disconnect the ECU and sensor connectors other than the DLC3 branch lines and CAN main bus lines between the CAN LH J/C and CAN RH J/C.
Using an ohmmeter, measure the resistance between terminals 6 (CANH) and 16 (BAT), and between terminals 14 (CANL) and 16 (BAT) of the DLC3 each time a connector is disconnected.
| CAN LH J/C A Side (with Earth Terminal) | Code | Color (CANH Side) | Color (CANL Side) |
| Steering angle sensor | J1 | P | W |
| ECM | J2 | B | W |
| Seat belt control ECU | J3 | V | W |
| Center airbag sensor | J4 | R | W |
| CAN LH J/C B Side (without Earth Terminal) | Code | Color (CANH Side) | Color (CANL Side) |
| Yaw rate sensor | J5 | P | W |
| Skid control ECU | J6 | R | W |
| CAN main bus line (bus line connecting CAN LH J/C and CAN RH J/C) | J7 | B | W |
| DLC3 | J8 | G | W |
| Distance control ECU | J9 | GR | W |
| CAN RH J/C A Side (with Earth Terminal) | Code | Color (CANH Side) | Color (CANL Side) |
| CAN main bus line (bus line connecting CAN RH J/C and CAN LH J/C) | J81 | B | W |
| Power steering ECU | J82 | P | W |
| Television camera ECU | J94 | L | W |
| CAN RH J/C B Side (without Earth Terminal) | Code | Color (CANH Side) | Color (CANL Side) |
| Gateway ECU | J84 | B | W |
- NOTICE:
- Do not reconnect the disconnected connectors until this inspection is complete because there may be a short to B+ in 2 or more CAN bus lines.
- Result:
Symptom Proceed to The resistance between terminals 6 (CANH) and 16 (BAT), or the resistance between 14 (CANL) and 16 (BAT) is still below 1 MΩ when all the specified connectors are disconnected from the CAN J/C. (There is a short to B+ in the CAN main bus lines between the CAN LH J/C and CAN RH J/C.) A The resistance between terminals 6 (CANH) and 16 (BAT), or the resistance between 14 (CANL) and 16 (BAT) becomes normal (1 MΩ or more) when a connector is disconnected from the CAN J/C. (There is a short to B+ in one of the areas that relate to one or more of the disconnected bus lines.) B
When there is a short to B+ in one or more of the bus lines that connect to an ECU (or sensor):
Reconnect all of the connectors to the CAN J/C, except for the one that was disconnected last (the bus line that is shorted to B+). Check that the resistance shown on the tester is normal (1 MΩ or more) to confirm that there is a short to B+ in the one bus line only.
- HINT:
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| B | |
| 4.RECONNECT CONNECTOR |
Reconnect the connector of the bus line that is shorted to B+ to the CAN J/C (the connector that caused the bus line resistance to change to 1 MΩ or more when it was disconnected).
| NEXT | |
| 5.CHECK FOR SHORT TO B+ IN CAN BUS LINE |
Disconnect the connector that includes terminals CANH and CANL from the ECU (or sensor) to which the bus line shorted to B+ is connected.
Measure the resistance according to the value(s) in the table below.
- Standard resistance:
Tester Connection Condition Specified Value J21-6 (CANH) - J21-16 (BAT) Engine switch off 1 MΩ or higher J21-14 (CANL) - J21-16 (BAT) Engine switch off 1 MΩ or higher
- HINT:
- If the resistance changes to 1 MΩ or higher when the connector is disconnected from the ECU (or sensor), there may be a short in the ECU (or sensor).
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| OK | ||
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