OBD II Fault Code P1657 :

Description of Fault code P1657

TCM-MULTIPLEX CONTROL UNIT MULTIPLEX LINE MALFUNCTION

Possible failuer P1657

• Communication line open
• Communication line short

Diagnostic Procedure using AutoHex II Scan Tool

• The malfunction is detected when the Engine is started, the voltage from IG1 is more than 10.5V, and the input voltage from VBU to TCM is less than 6V, at least 2 seconds.

Test Conditions using AutoHex tester

• ENGINE SPEED > 400rpm
• Battery Voltage > 10.5V

Clear Fault codes Conditions

• The malfunction is detected when the Engine is started, the voltage from IG1 is more than 10.5V, and the input voltage from VBU to TCM is less than 6V, at least 2 seconds.

MIL Status

• ON

Note:

• AutoHex II is a professional Auto diagnostic.
• This fault code is a GERENRIC fault code, some cars may change the meaning of this fault code.
  To get the accurate fault code description you may use AutoHex II

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