P1D20 - Multi Module Handshake Failure

Repair Importance Level: 3/3
Repair Difficulty Level: 3/3   
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Possible causes

  • Faulty Electronic Shifter Module (ESM) Internal Error
  • Faulty Transmission Control Module (TCM) Internal Error

Possible symptoms

  • Engine Light ON (or Service Engine Soon Warning Light)

P1d20 Description

The purpose of the diagnostic is to monitor the question-answer CAN communication between the Electronic Shifter Module (ESM) and the Transmission Control Module (TCM) by comparing the ESM response to the expected value within the TCM software. The TCM sends two randomly generated values to the ESM and the ESM is expected to answer with a value calculated based upon these two random numbers. The TCM commands the ESM to reset if one of the following conditions occurs: No answer received within a calibrated amount of time, received answer is incorrect and is the same as the previous answer or the received answer is incorrect and is not the same as the previous answer.
OBDII Code P1d20 - Multi Module Handshake Failure - AutoCodes.com

P1D20 Information for specific makes

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P1D20 Comments

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