What sensors does the ECM use to control the IAC valve?

Per the diagram, the ECM receives engine speed (CMP sensor), throttle valve opening (TP sensor), engine coolant temperature (ECT sensor), vehicle speed (VSS), shift range signal (shift switch, A/T only), A/C ON signal (A/C amplifier, if equipped), power steering signal (power steering pressure switch, if equipped), battery voltage, diagnosis signal (diag. switch terminal), and intake air volume (MAF sensor).

Where is the IAC valve located?

The illustration shows the IAC valve (callout 1) mounted on the throttle body (callout 2).

How does the ECM drive the IAC valve?

The timing chart shows an ON/OFF duty-cycle signal: the 1-cycle period is constant while the ON time varies, so idle air is controlled by changing the ON-time ratio.

Is the shift switch input used on all transmissions?

No — the diagram notes the "R", "D", "2" or "L" range signal comes from the shift switch on automatic transmission (A/T) vehicles only.

Are the A/C and power steering inputs on every vehicle?

No — the A/C amplifier and power steering pressure switch inputs are both marked "if equipped".

Home/ Registry/ Suzuki/ Samurai/ 1986-1995/ “Little Blue”/ Photo supermotors.net/registry/media/420672

Suzuki Samurai IAC Valve & ECM Idle Air Control System Diagram - Sensor Inputs

Schematic of IAC valve and throttle body showing ECM input signals from CMP, TP, ECT, VSS and MAF sensors

‹ ›

Schematic of the idle air control valve and throttle body with a cutaway and the ECM input signals from the engine sensors.

AI caption August 2006 · Photo 41 of 86

This schematic documents the Idle Air Control (IAC) system as part of the engine control / EFI system. It shows a cutaway illustration of the IAC valve (callout 1) mounted on the throttle body (callout 2), with air passages routed around the throttle plate into the intake. A block diagram shows the ECM and the input signals it uses to control the IAC valve: engine speed from the CMP sensor, throttle valve opening from the TP sensor, engine coolant temperature from the ECT sensor, vehicle speed from the VSS, an "R", "D", "2" or "L" range signal from the shift switch (automatic transmission only), an A/C ON signal from the A/C amplifier (if equipped), a power steering signal from the power steering pressure switch (if equipped), battery voltage, a diagnosis signal from the diagnostic switch terminal, and intake air volume from the MAF sensor. A timing chart at the bottom illustrates that the ECM drives the IAC valve with an ON/OFF duty-cycle signal: the cycle length is constant while the ON time within each cycle varies to regulate idle air flow. A reader learns which sensors influence idle control and how the valve is duty-cycle modulated.

Is this accurate? Sign in to help verify it.

Frequently asked questions

What sensors does the ECM use to control the IAC valve?: Per the diagram, the ECM receives engine speed (CMP sensor), throttle valve opening (TP sensor), engine coolant temperature (ECT sensor), vehicle speed (VSS), shift range signal (shift switch, A/T only), A/C ON signal (A/C amplifier, if equipped), power steering signal (power steering pressure switch, if equipped), battery voltage, diagnosis signal (diag. switch terminal), and intake air volume (MAF sensor).
Where is the IAC valve located?: The illustration shows the IAC valve (callout 1) mounted on the throttle body (callout 2).
How does the ECM drive the IAC valve?: The timing chart shows an ON/OFF duty-cycle signal: the 1-cycle period is constant while the ON time varies, so idle air is controlled by changing the ON-time ratio.
Is the shift switch input used on all transmissions?: No — the diagram notes the "R", "D", "2" or "L" range signal comes from the shift switch on automatic transmission (A/T) vehicles only.
Are the A/C and power steering inputs on every vehicle?: No — the A/C amplifier and power steering pressure switch inputs are both marked "if equipped".