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Home >> Toyota >> 2021 >> 4Runner TRD Off-Road >> Repair and Diagnosis >> External Pages >> Different variant/trim >> Section 8 (Touch Select 2-4 And High-Low System (VF2CM) - Diagnostic Codes & Circuit Tests) >> Touch Select 2-4 And High-Low System >> DTC P17A4: Automatic Disconnecting Differential Motor Limit Switch Circuit [08/2019 - ] >> Description

DTC P17A4: Automatic Disconnecting Differential Motor Limit Switch Circuit [08/2019 - ]: Description

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When the A.D.D. actuator switches between 2WD and 4WD, the DL1 and DL2 terminals of the limit switch and ADD terminal of the A.D.D. position switch change to one of the following ON/OFF combinations listed in the table below.

Terminal In 2WD Switching between 2WD and 4WD In 4WD
DL1 ON (GND) ON (GND) OFF (OPEN)
DL2 OFF (OPEN) ON (GND) ON (GND)
ADD OFF (OPEN) OFF (OPEN) ON (GND) ON (GND)

A malfunction is detected depending on the combination of the 3 circuits that make up the limit switch and A.D.D. position switch.

DTC No. Detection Item DTC Detection Condition Trouble Area
P17A4 Automatic Disconnecting Differential Motor Limit Switch Circuit
  • Diagnosis Condition: Directly after the engine ignition switch turned to ON, or while switching between H2 and H4 (A.D.D. shift motor operating) with the ignition switch turned to ON
  • Malfunction Status: The ON/OFF combination of DL1, DL2 and ADD does not match the pattern
  • Malfunction Time: 0 seconds
  • Other: 1 trip detection logic
  • Wire harness and connector
  • 4 wheel drive control ECU
  • A.D.D. actuator (differential vacuum actuator assembly)