Intermittent Starting and Stalling - CPS Wiring Failure and Rebuild

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Problem

7MGTE MKIII Supra has intermittent starting issues and stalling. Sometimes starts immediately, other times requires physically manipulating the wires on the Cam Position Sensor (CPS) to get it to start. Moving the CPS wires even a couple millimeters can cause the engine to immediately die.

Intermittent no-start conditionEngine starts only after finessing/wiggling CPS wiresRandom stalling while drivingMoving CPS wires a couple millimeters causes immediate engine shutdownCPS-side wires are hard, brittle, and corroded

Root Cause

The original CPS wiring becomes hard, brittle, and corroded with age. The internal connections fail intermittently, causing loss of the cam position signal needed for ignition. This is a very common failure on aging MKIII Supras. Previous attempted repairs (twisted wires under shrink tube) may also contribute to unreliable connections.

Confidence

Moderate confidence — Multiple community members agreed on this solution

View Original Thread →Posted April 2022 on SupraForums.com