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.
DTC B1273: Sliding Roof ECU Communication Stop: Procedure
- CHECK HARNESS AND CONNECTOR (METALTOP CONTROL ECU - BATTERY AND BODY GROUND)
- Disconnect the Q36 connector.
- Measure the voltage and resistance according to the value(s) in the table below.
Standard Voltage
Tester Connection Condition Specified Condition Q36-6 (ECUB) - Body ground Always 11 to 14 V Standard Resistance
Tester Connection Condition Specified Condition Q36-5 (SGND) - Body ground Always Below 1 Ω TEXT IN ILLUSTRATION*1 Front view of wire harness connector
(to Metaltop Control ECU (Sliding Roof Control ECU Assembly))
NG → REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to next step
- Disconnect the Q36 connector.
- CHECK HARNESS AND CONNECTOR (COMMUNICATION LINE)
- Disconnect the Q3 and M17 connectors.
- Measure the resistance according to the value(s) in the table below.
Standard Resistance
Tester Connection Condition Specified Condition Q36-23 (MPX1) - M17-7 (MPX1) Always Below 1 Ω Q36-24 (MPX1) - Q3-15 (MPX1) Always Below 1 Ω TEXT IN ILLUSTRATION*1 Front view of wire harness connector
(to Metaltop Control ECU (Sliding Roof Control ECU Assembly))*2 Front view of wire harness connector
(to Main Body ECU LH (Cowl Side Junction Block LH))*3 Front view of wire harness connector
(to Power Window Regulator Master Switch Assembly)- -
NG → REPAIR OR REPLACE HARNESS OR CONNECTOR
OK: Go to next step
- Disconnect the Q3 and M17 connectors.
- REPLACE METALTOP CONTROL ECU (SLIDING ROOF CONTROL ECU ASSEMBLY)
- Replace the metaltop control ECU (sliding roof control ECU assembly). Refer to REMOVAL [08/2012 - ] .
NEXT: Go to next step
- CHECK DTC OUTPUT
- Clear the DTC. Refer to DTC CHECK / CLEAR [08/2012 - ] .
- Recheck for DTCs.
OK
DTC B1273 is not output.
NG → See step 5
OK → END (METALTOP CONTROL ECU WAS DEFECTIVE)
- REPLACE GATEWAY ECU. Refer to REMOVAL [08/2012 - ]
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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.
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