DTC P104A: VALVEMATIC SDOWN Circuit [01/2019 - 03/2019]: Description

WARNING: This page is about a different car, the 2022 Toyota Corolla, 2021 Toyota Corolla, 2020 Toyota Corolla, and 2019 Toyota Corolla. However, it is still accessible from the selected car via links, so may be relevant.

The ECM turns the power supply to the continuously variable valve lift controller assembly on/off. Normally, when the ignition switch is ON, +B voltage is constantly supplied to the continuously variable valve lift controller assembly. However, when a malfunction is detected in the VALVEMATIC system, the ECM turns the power supply to the continuously variable valve lift controller assembly off. The power supply is turned on/off through the shutdown (SDWN) signal line between the ECM and continuously variable valve lift controller assembly.

DTC No.	Detection Item	DTC Detection Condition	Trouble Area	MIL	Memory
P104A	VALVEMATIC SDOWN Circuit	Shutdown (SDWN) signal line has a short circuit to +B or ground (1 trip detection logic): Shutdown (SDWN) signal line short circuit to +B: While the ignition switch is off, even though the CPU in the ECM requests shutdown (SDWN) signal Low, the monitor detects High Short circuit (Short circuit to ground): While the ignition switch is ON, even though the CPU in the ECM requests shutdown (SDWN) signal High, the monitor detects Low	Short in continuously variable valve lift controller assembly circuit ECM	Comes on	DTC stored