How does the iacv connect to the pcu? - 1999 Toyota RAV4

IACV= idle air control valve.it allows, and controls the amount of air into the intake when the car is at idle..and your MAFS, mass air flow sensor is connected to your air filter. It will be between the air filter and the engine in the breather tube.

unplug the battery for 15 mins if it does the same thing leave the key on without starting for 1 min it should move up and down till it repositions itself you can almost hear it working with the key on and if all comes down to it it could be damaged or stuck you might have to check it again and make sure it s plugged good or a vacume hose off near the throttle you might have pulled it off without knowing

P0505 - Idle Control System Malfunctionhttp://engine-codes.com/p0505.htmlForum CodePossible causes- IACV-AAC valve harness is open or shorted
- IACV-AAC valve poor electrical connection
- Faulty IACV-AAC valve

Read more: http://engine-codes.com/p0505.html#ixzz1zVJIt34L

Disconnect the iacv and if the idling performance doesn't change from what you are experiencing then it may not be turning or the passageways are clogged and need to be sprayed out with cleaner.

One can test the continuity of the iacv to see if it is within specifications using a multimeter.

One can turn the a/c on and if the car stalls, then the iacv may not be working.

Good luck on this diagnosis.

You probably have a bad Idle Air Control Valve (IACV). If it does not control the idle correctly , you can find yourself driving 50 MPH with out touching the gas pedal. The IACV is located on the throttle control valve and is typically held on by two or three small screws. The price for an IACV can run from $25 to $500. I purchased a throttle body for $40 , removed the IACV, and saved $400.

I can think of four things. Do each in turn and test the engine after completing each one. If it gets fixed early in the list avoid the items later on. 1) check that your throttle interior is clean 'like new' along with the idle air control valve.
2) Idle Air Control Valve IACV - How to check? Physically remove the IACV but keep the electrical connection to it and loosely blank off the ports to the throttle inlet assembly, exposed by the IACV removal. Turn the engine on and examine the IACV valve movement in response to additional loads (power steering inputs etc). The valve should open and close according to demand causing perceptible change in engine speed with increased power demand being made on the engine.

The electrical connector to the IACV can have 2 or 4 pins:-

2 pins: resistance between pins should about 10 OHMS +/- 3 OHMS. Resistance between either of the pins and the valve body is greater than 10,000 OHMS

4 pins: resistance between diagonally positioned pins should be about 20 OHMS
How to fix? If the motor of the IACV has failed then replace it. If the valve is gummed closed by baked oil and carbon then clean it thoroughly with carburetor choke cleaner spray and a cloth. Similarly if the entry and exit ports on the throttle body to the IACV look blocked again clean them out thoroughly
3) Throttle Position Sensor TPS - How to check? The socket for electrical connection with the TPS has 3 pins, one for 'ground', one for 5 volts 'reference' and a third (generally the middle one) for 'signal' output. Back probe the signal pin in the connector to the TPS. Attach the positive lead of a voltmeter to the probe and measure the voltage output as the throttle plate is rotated. If working correctly the meter should show a voltage consistent with the throttle position from approximately 1 volt when closed and 5 volts when fully open. What is looked for is smooth voltage increase with throttle change. If there are drop outs in the transition or that there is no transition seen the TPS is faulty.

How to fix? If the track is dirty causing drop outs, try cleaning it with residue-free electrical cleaning spray. If the track is worn it is perhaps easiest to replace the complete device. In some instances it may be possible to adjust the location of the central mount of the TPS contact arm along the throttle shaft by a few millimeters and in the process cause a fresh concentric region of

4) Fuel pressure regulator _ Yes I know you have checked it for pressure but at start up when the ignition is at position 2 the fuel pump starts up and pressurizes the fuel rail. As you turn to position 3 "ignition" power is cut to the pump and fuel pressure is maintained by a non-return valve in the pump. If that valve is faulty the fuel pressure in the rail will drop to zero just when you need it and no fuel can be injected. Check the fuel pressure when at position 2 and then switched off; fuel pressure should be maintained for up to 5 minutes with little or no loss. If there is pressure loss then either the non-return valve is faulty or you have leak in the fuel pressure regulator. If it is such a leak, fuel will dribble from the vacuum line connected to it when disconnected.

Make sure the throttle body interior and throttle plate are clean and then check both the 1) idle air control valve and the 2) throttle position sensor:
1) Idle air control valve - How to check? Physically remove the IACV, keep the electrical connection to it and blank off the port to the intake plenum. Turn the engine on (you will need a little accelerator pedal pressure to keep her running) and examine the IACV valve movement in response to additional loads (power steering inputs etc). The valve should open and close according to demand which when fitted would cause change in engine speed with increased power demand made on the engine.

The electrical connector to the IACV can have 2 or 4 pins:-

2 pins: resistance between pins should about 10 OHMS +/- 3 OHMS. Resistance between either of the pins and the valve body is greater than 10,000 OHMS

4 pins: resistance between diagonally positioned pins should be about 20 OHMS

How to fix? If the motor of the IACV has failed then replace it. If the valve is gummed closed by baked oil and carbon then clean it thoroughly with carburetor choke cleaner spray and a cloth. Similarly if the entry and exit ports on the throttle body to the IACV look blocked again clean them out thoroughly.

2) Throttle position sensor - How to check? The socket for electrical connection with the TPS has 3 pins, one for 'ground', one for 5 volts 'reference' and a third (generally the middle one) for 'signal' output. Back probe the signal pin in the connector to the TPS. Attach the positive lead of a voltmeter to the probe and measure the voltage output as the throttle plate is rotated. If working correctly the meter should show a voltage consistent with the throttle position from approximately 1 volt when closed and 5 volts when fully open. What is looked for is smooth voltage increase with throttle change. If there are drop outs in the transition or that there is no transition seen the TPS is faulty.

How to fix? If the track is dirty causing drop outs, try cleaning it with residue-free electrical cleaning spray. If the track is worn it is perhaps easiest to replace the complete device. In some instances it may be possible to adjust the location of the central mount of the TPS contact arm along the throttle shaft by a few millimeters and in the process cause a fresh concentric region of track to be used.

Check the Idle Control System

Idle speed is controlled by the Idle Air Control Valve (IACV). The IACV changes the amount of air being bypassed to the intake manifold, in response to electric current controlled by the ECM. When the IACV is activated, the valve opens to maintain proper idle speed.

Symptom and Subsystems to Check:

1. Difficult to start engine, when cold--check Fast Idle Thermo Valve.

2. Fast idle out of spec, when cold:
a. Check Fast Idle Thermo Valve.
b. Check IACV.
c. Check idle adjusting screw (see Section C).

3. Rough idle:
a. Check hoses and connections.
b. Check IACV.

4. RPM too high, when warm:
a. Check IACV.
b. Check Fast Idle Thermo Valve.
c. Check hoses and connections, check Power Steering Pressure Switch Signal, and check idle adjusting screw.

5. RPM too low, when warm:
a. Idle speed is below specified rpm, with no load--check IACV and idle adjusting screw.
b. Idle speed doesn't increase after initial start up--check IACV.
c. Idle speed drops in gear (automatic transmission)--check automatic transaxle gear position switch signal.
d. Idle speed drops when AC is on--check air conditioning signal and IACV.
e. Idle speed drops when steering wheel is turned--check power steering pressure switch signal and IACV.
f. Idle speed fluctuates with electrical load--check hoses and connections, IACV, and Alternator FR Signal.

6. Frequent stalling, while warming up--check IACV and idle adjusting screw.

7. Frequent stalling, after warming up--check idle adjusting screw and IACV.

Additional Steps:

. Check Alternator FR Signal. Have alternator inspected, if idle speed fluctuates with electrical load. The FR signal communicates to the ECM how "hard" the alternator is working to meet the electrical demands of the car, including the battery and any loads which aren't monitored by the ELD. This square-wave signal varies in pulse width, according to the load on the alternator. The ECM places, approximately, 5 reference volts on the wire. The voltage regulator will drop this signal to approximately 1.2 volts, in proportion to alternator load. The ECM compares the electrical load (ELD) signal with the FR (Charging Rate) signal from the alternator and uses that information to set the idle speed and turn the alternator on and off. This helps fuel economy.

. Clean main ECM ground on thermostat housing.

. Reset ECM, by removing the 7.5 amp Back Up Fuse, in the under-hood fuse box, for 10 seconds.

. Replace PCV Valve, cleaning hose with brake cleaner spray.

. Substitute a known-good ECM. If symptom goes away, replace original ECM.

Check the ICM (Erratic RPM and PGM-FI System)

When the engine is cold, the air conditioner compressor is on, the transmission is in gear (automatic transmission only) or the alternator is charging, the ECM controls current to the Idle Air Control (IAC) Valve to maintain correct idle speed. Here's an overview of how the PGM-FI System works.

Background:

Various inputs to the ECM are TDC/CKP/CYP Sensor, MAP Sensor, ECT Sensor, IAT Sensor, TP Sensor, HO2S, VSS, BARO Sensor, EGR Valve Lift Sensor, Starter Signal, Alternator FR Signal, Air Conditioning Signal, Automatic Transmission Shift Position Signal, Battery Voltage (Ignition 1) Brake Switch Signal, PSP Switch Signal, ELD, and VTEC Pressure Switch.

Inputs are received and processed by the ECM's Fuel Injector Timing and Duration, Electronic Idle Control, Other Control Functions, Ignition Timing Control, and ECM Back-up Functions. These are the primary functional areas within the ECM.

Outputs from the ECM control Fuel Injectors, PGM-FI Main Relay (Fuel Pump), MIL (Check Engine Light), Idle Air Control (IAC) Valve, A/C Compressor Clutch Relay, Ignition Control Module (ICM), EVAP Purge Control Solenoid Valve, HO2S Heater, EGR Control Solenoid Valve, Alternator, Lock-up Solenoid Valve A/B (A/T), VTEC Solenoid Valve, and Interlock Control Unit.

Idle RPM:

Once you understand how the PGM-FI system is configured, it's easy to see how the ECM, Idle Air Control Valve, and the Ignition Control Module affect idle rpm. If the ECM's Electronic Idle Control function is not working properly, then it cannot properly control the IAC Valve. Likewise, if the ECM's Ignition Timing Control function is not operating properly, it cannot properly control the ICM (igniter). Obviously, idle rpm will also be affected if there's a problem with the IAC Valve or the ICM. As stated above, the ECM controls current to the Idle Air Control (IAC) Valve to maintain correct idle speed. This cannot happen if the IAC Valve is failing. The same situation exists if the ICM is failing. The ECM will tell the ICM to open and close the primary voltage circuit going to the coil and it won't respond properly. The result will be erratic spark plug firing and erratic rpm.

Conclusion:

If you are experiencing erratic idle rpm, try and isolate whether the problem is caused by the ICM (ignitor), IAC Valve, or the ECM. My experience has been that a failing ICM is usually responsible for the problem. Keep in mind that tachometers are connected directly to the ICM. Therefore, a fluctuating tachometer needle is often a dead giveaway. Heat and poor preventive maintenance (causing high secondary voltage to be discharge on internal distributor components) frequently causes the ICM (and coil) to fail. Besides performance, this is another reason why it's important to regularly replace spark plugs, spark plug wires, rotors, and distributor caps. Electricity will always follow the path of least resistance, even if it isn't the intended one. Our job is to ensure the intended path is the path of least resistance.

Ignitor (ICM) and Coil Replacement:

1. Disconnect negative battery cable.
2. Remove hex head machine screws, securing distributor cap to housing, using an 8 mm nut driver.
3. Move distributor cap and wires off to the side.
4. Remove machine screw securing rotor to shaft, using a #2 Phillips head screwdriver. It may be necessary to "hit" the starter once or twice, in order to rotate rotor for access to mounting screw.
5. Remove rotor and leak cover.
6. Unfasten ignitor wires, remove coil mounting screws, and set coil aside. Note: Removing coil first improves access to igniter.
7. Unfasten screws securing igniter to housing.
8. Remove ignitor from distributor and unfasten screws mounting ignitor to heat sink.
9. Coat back of new ignitor (or old igniter, if reusing) and male connectors with silicone grease. Silicone grease increases heat transfer to heat sink. Failure to apply silicone grease will cause the ignitor to quickly fail.
10. Mount ignitor to heat sink and reinstall ignitor, igniter terminal wires, coil, coil wires, leak cover, rotor, and distributor cap. Ensure female ignitor terminals fit snugly--crimp with pliers, if necessary.

AutoZone can test ICMs and coils for free. If you plan to keep the car, I would replace the ICM due the age of your Civic.

I can't speak to the leak, but the inability to idle is due to a bad low idle control valve. My 2000 RX300 was doing the exact same thing. It's about a $450 part.