On Toyota's with a push button start the ECM will power the starter relay for 30 seconds or until the engine reaches 500 RPM for 500ms. Other makes may use a different strategy.
A43-5 (STAR) - Body ground Input/Output P - Body ground Outputs
voltage to the starter relay
Outputs voltage (12 V) to the starter relay when starting the engine.
(Max. 30 sec. Turns off when an engine speed of 500 rpm or more
continues for 500 ms or more.)
HINT: When Hi is selected, a start request signal (STAR) will not be
output even though a start request signal (STSW) is input. Shift lever
in any position other than P or N → shift lever in P or N (at 20°C
(68°F)) 10 kΩ or higher → 93.75 to 136.36 Ω - Receives neutral start
switch (P, N position detection) signal
Monitors whether the neutral start switch is on (P or N) or off (other
than P or N). Applies voltage via a resistor (large) in the
certification ECU (smart key ECU assembly). When the neutral start
switch is on, due to the starter relay coil resistance (small) using
some of the voltage, the voltage at terminal STAR will be low (2.7 V
or less), and when the neutral start switch is off, the voltage will
be high (9 V or more).
Perform the following operations except while the engine is cranking:
Shift lever in any position other than P or N → shift lever in P or
N(at 20°C (68°F))
30 kΩ or higher → 93.75 to 136.36 Ω Neutral SW/ Clutch SW