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P0899 Powertrain

Transmission Control System MIL Request Circuit High

Voltage on the transmission control system MIL request circuit is above the expected window. Wire shorted to B+ or driver open.

Affected components

  • Mil request circuit
  • Tcm

Common causes

  • High likelihood: Wire shorted to B+
  • Medium likelihood: Driver fault open
  • Low likelihood: Connector pins corroded - high contact resistance

Possible symptoms

  • Check engine or transmission warning light on
  • Harsh, delayed, or missing shifts
  • Possible limp mode (locked in one gear)
  • Slipping or shuddering during gear changes

Diagnostic notes

  • The malfunction indicator lamp may illuminate

Sources

Diagnostic information is provided for reference only. Confirm the code with a compatible scan tool and follow the vehicle manufacturer's service procedures before replacing components.

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