Model Year 2013
Thomas bus all mirror no heat.
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Check the fuse. 2A good, has power.
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Cut the wire to the left side cross over mirror. Check ground. Two wires all grounded. The problem is the power wire grounded. Need to find the point where the power wire grounded.
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Remove the entrance door top cover, disconnect the wire to the passenger side mirror. Check ground. Two wires all grounded. For the power supply to all the mirrors are connected. So the grounded point may happen everywhere is possible. My thoughts, disconnect every connector to each mirror. Total 6 mirrors. Find the ground point piece by piece which is time cost.
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Change a mind after doing two pieces, try to swap the switch on the driver side left dash to see, key on, switch on, check the power supply to the left crossover mirror. About 9v. Has power but the number is not normal. usually should around 12V. But all the other mirrors except the left front crossover mirror all has heat.
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Switch off, key off. Connect the left side crossover mirror. All the mirrors no heat. Swap the two switch back. Same. Disconnect the left crossover mirror again, swap the switch. Key on, switch on. All mirrors no heat. I suspect the problem is the CHM.
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Use needle pin to test power out put from Pin J and Pin S from C3 where to the front, Pin P and Pin J from C4 where power to front. Has power 12v, normal.
Please see details from the Inspection Procedure – M2 Chassis Module
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My opinion, there is the logical error where the switch signal to the CHM, CHM did not give power to the mirror or give the wrong voltage. Replace CHM
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Disconnect battery negative, disconnect all the connectors to the CHM. Remove the CHM
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Compare new and old CHM
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Install new CHM
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Test the power to the left front crossover mirror. 12V noraml. All mirrors have heat. Problem solved.
