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Tim West
Tim West, ASE Certified Technician
Category: Car
Satisfied Customers: 4638
Experience:  ASE Certified Service Manager for Bridgstone/ Firestone
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I have a p1569 (VTCS Circuit Low Input) code on my 2000 Mazda

Resolved Question:

I have a p1569 (VTCS Circuit Low Input) code on my 2000 Mazda 626. is there another name for the VTCS Valve? and can you tell me what I need to do in order to fix this problem?
Submitted: 7 years ago.
Category: Car
Expert:  Tim West replied 7 years ago.
Thanks for visiting Just Answer,

Variable Tumble Control System (VTCS) Solenoid


1. Disconnect the negative battery cable.
2. Remove the intake manifold.


3. Remove in the order indicated in the table.
4. Install in the reverse order of removal.


  • The PCM turns the variable tumble control solenoid valve ON to close the crescent shaped shutter valve in the intake manifold when all of the following conditions have been met:
  1. ECT is below 65°C (149°F).
    1. Engine speed is below 3,000 rpm.
    2. Throttle opening angle is below preset value.
    3. ECT sensor and TP sensor are not malfunctioning.
    • The PCM turns the VTCS solenoid valve OFF to maintain startability and stability during engine cranking and for 0.15 second after engine is started.

Block Diagram

Variable Tumble Control System (VTCS) Solenoid Valve Description

  • VTCS solenoid valve supplies intake manifold vacuum or atmosphere to the VTCS for shutter valve actuation.


  • VTCS solenoid valve is mainly composed of a coil, spring, plunger and filter.

Operation (energized)

  • The plunger is pulled back to open the air passage between the VTCS delay valve and VTCS vacuum chamber, which applies the intake manifold vacuum to the VTCS shutter valve actuator.

Operation (de-energized)

  • The plunger is returned forward to open the air passage between the VTCS delay valve and the VTCS solenoid valve air filter applies the vacuum is then vented to atmosphere and the VTCS shutter valve actuator.


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