Air Conditioning System - Diagnostics: Diagnosis Toyota 4Runner IV

HOW TO PROCEED WITH TROUBLESHOOTING

1. Vehicle Brought To Work Shop
2. (See «CUSTOMER PROBLEM ANALYSIS»(ref-190085-S36246013442005091300000) )
3. Check And Clear DTC (See «PRE-CHECK»(ref-190085-S30534238632005091300000) )
4. Problem Symptom Confirmation : Symptom Occur (Go To Step 6 ) : Symptom Does Not Occur (Go To Step 5)
5. (See «SYMPTOM SIMULATION»(ref-190050-S14480022552005091300000) )
6. DTC Check (See «PRE-CHECK»(ref-190085-S30534238632005091300000) ) Malfunction Code (Go To Step 7) Normal Code (Go To Step 8 )
7. DTC Chart (See Page «DIAGNOSTIC TROUBLE CODE CHART»(ref-190085-S07534863972005091300000) ) Go To Step 10
8. (See «PROBLEM SYMPTOMS TABLE»(ref-190085-S28799716772005091300000) )
9. Actuator Check (See «HOW TO PROCEED WITH TROUBLESHOOTING»(ref-190050-S05771891582005091300000) )
10. Circuit Inspection (See «DTC 11 ROOM TEMPERATURE SENSOR CIRCUIT»(ref-190085-S02894350142005091300000) - «HEATER CONTROL PANEL COMMUNICATION CIRCUIT»(ref-190085-S36742097482005091300000) )
11. Identification Of Problem
12. Parts Inspection
13. Repair
14. Confirmation Test
15. End

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1. Warning For A/C Compressor Lock If the compressor lock occurs during A/C operation, the A/C switch indicator on the A/C control panel starts blinking. When this occurs, check for compressor lock (DTC 22) using diagnosis trouble code. And then proceed to inspect the circuit or the component. Compressor lock sensor circuit (See «DTC 22 COMPRESSOR LOCK SENSOR CIRCUIT»(ref-190085-S04051672932005091300000) )
2. List Of Operation Methods By operating each of the A/C control switches as shown in the diagram below, it is possible to enter the diagnosis check mode.
3. Indicator Check Turn the ignition switch to ON while pressing the A/C control "AUTO" switch and "R/F" switch simultaneously. Check that the indicators come on and go off 4 times at 1 second intervals in succession. NOTE: After the indicator check is completed, the system enters the DTC automatically. Press the OFF switch when canceling the check mode.
4. DTC Check (Sensor Check) Perform an indicator check. After the indicator check is completed, the system enters the DTC check mode automatically. Read the code displayed on the panel. Refer to the list of codes on page «DIAGNOSTIC TROUBLE CODE CHART»(ref-190085-S07534863972005091300000) when reading the codes. (Trouble codes are output on the temperature display.) If the slower display is desired, press the FRONT DEF switch and change it to stepped operation. Each time the FRONT DEF switch is pressed, the display changes by 1 step.
5. Clearing DTC Clear DTC memory by one of the following methods. Method 1: During the sensor check, press "DEF" switch and "REAR DEF" switch at the same time. Method 2: Pull the ECU-B fuse in the engine room J/B for 20 sec. or longer.
6. Actuator Check After entering the DTC check mode (Sensor Check Mode), press the R/F switch. Since each damper, motor and relay automatically operates at 1 sec. intervals beginning in order from 10 in the temperature display, check the temperature and air flow visually and by hand. If slower display is desired, press the DEF switch and change it to the step operation. Each time the DEF switch is pressed, the display changes by 1 step. NOTE: Code are displayed in order from the smaller to the larger numbers. To cancel the check mode, press the OFF switch.
7. Diagnosis System Check DLC3. The vehicle's ECM uses ISO 9141-2 for communication. The terminal arrangement of DLC3 complies with SAE J1962 and matches the ISO 9141-2 format. TERMINAL CONNECTION VOLTAGE OR RESISTANCE Terminal No Connection/Voltage or Resistance Condition 4 Chassis Ground - Body Ground/1 ohm or less Always 16 Battery Positive - Body Ground/9 - 14 V Always NOTE: If your display shows UNABLE TO CONNECT TO VEHICLE when you have connected the cable of the hand-held tester to the DLC3, turned the ignition switch ON and operated the scan tool, there is a problem on the vehicle side or tool side. If the communication is normal when the tool is connected to another vehicle, inspect the DLC3 on the original vehicle. If the communication is still impossible when the tool is connected to another vehicle, the problem is probably in the tool itself, so consult the Service Department listed in the tool's instruction manual.
8. Data List NOTE: By the DATA LIST displayed by the Hand-held tester, you can read the value of the switch, sensor, actuator, etc. Without removing any parts. Reading the DATA LIST as a first step of troubleshooting is one of the method to shorten the labor time. Connect the Hand-held tester to the DLC3. Turn the ignition switch ON. According to the display on tester, read the "DATA LIST". DATA LIST Item Measurement Item/Range (Display) Normal Condition Diagnostic Note A/C SIG A/C signal/ON, OFF - - A/C CUT SIG A/C cut signal/ON, OFF

DIAGNOSTIC TROUBLE CODE CHART

If malfunction code is displayed during the DTC check (sensor check), check the circuit listed for that code in the table below (Proceed to the page given for that circuit).

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PROBLEM SYMPTOMS TABLE

If the normal code is displayed during DTC check although the problem still occurs, check the circuits for each problem symptom in the order given in the table below, and proceed to the relevant troubleshooting.

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DIAGNOSTIC TROUBLE CODE TESTS

DIAGNOSTIC TROUBLE CODE DEFINITIONS

CIRCUIT DESCRIPTION

This sensor detects the temperature inside the cabin and sends appropriate signals to the A/C amplifier.

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This sensor detects the temperature outside the cabin and sends appropriate signals to the A/C amplifier.

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This sensor detects the temperature inside the cooling unit and sends appropriate signals to the A/C amplifier.

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This circuit converts the resistance of the engine coolant temperature sensor into a pulse signal and transmits to the A/C amplifier.

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A photo diode in the cooler (solar sensor) thermistor detects solar radiation and sends signals to the A/C amplifier.

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This sensor sends 4 pulses par engine revolution to the A/C amplifier. If the ratio of the compressor speed divided by the engine speed is smaller than a predetermined value, the A/C amplifier turns the compressor off, and the indicator flashes at about 1 sec. intervals.

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The pressure switch sends appropriate signals to the A/C amplifier when the A/C refrigerant pressure drops too low or rises too high. When the A/C amplifier receives these signals, it outputs signals via the A/C amplifier to switch OFF the compressor relay and turn OFF the magnetic clutch.

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This sensor detects the position of the air mix damper and sends the appropriate signals to the A/C amplifier. The position sensor is built into the damper servo sub-assy (air mix damper control servomotor).

Note. This DTC is indicated only for limited grade (right/left independent temperature control system).

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This damper servo sub-assy (air mix damper control servomotor) is controlled by the A/C amplifier and moves the air mix damper to the desired position.

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The blower damper servo sub-assy (air inlet damper control servomotor) is controlled by the A/C amplifier and moves the air inlet damper to the desired position.

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This circuit turns the servomotor and changes each mode damper position by the signals from the A/C amplifier. When the AUTO switch is on, the A/C amplifier changes the mode automatically between (FACE), (BI-LEVEL) and (FOOT) according to the temperature setting.

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The damper servo sub-assy (air mix damper control servomotor) is controlled by the A/C amplifier and moves the air mix damper to the desired position.

Note. This DTC is displayed for only limited grade (right/left independent temperature control system).

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This circuit is the power source for the A/C amplifier assy (contains the ECU), servomotor, etc.

This is the back-up power source for the A/C amplifier. Power is supplied even when the ignition switch is off and the power is used for backing up diagnostic trouble code memory, etc.

The heater relay is switched on by signals from the A/C amplifier. It supplies power to the blower motor.

The blower motor is operated by signals from the A/C amplifier.

Blower motor speed signals are transmitted by changes in the Duty Ratio.

Duty Ratio

The duty ratio is the ratio of the period of continuity in one cycle.

For example, if A is the period of continuity in one cycle, and B is the period of non-continuity, then.

Scheme 32

This is a driving circuit of the A/C magnetic clutch and controlled by the ECU terminal below.

1. ACS of the A/C amplifier: Output the A/C switch condition "ON" or "OFF".
2. THE of A/C amplifier: Output the request signal to drive the magnetic clutch, and send it to ECM.
3. ACMG of ECM: Operates the cooler relay assy and drive the magnetic clutch.

The A/C amplifier monitors the vehicle speed through the signals sent from the speed sensor. The A/C amplifier uses these signals to revise the ambient temperature sensor signal.

This circuit is a power supply for the air conditioning control assy (heater control panel).

This circuit is a communication line between the air conditioning control assy (heater control panel) and the A/C amplifier.

CIRCUIT INSPECTION

1. Check Harness And Connector (Between Air Conditioning Control Assy And Air Conditioning Amplifier) Check for open and short circuit in the harness and the connector between the air conditioning control assy and A/C amplifier (See «ELECTRONIC CIRCUIT INSPECTION PROCEDURE»(ref-190050-S42441265552005091300000) ). NG : Repair Or Replace Harness Or Connector OK : Go To Next Step
2. Inspect Air Conditioning Control Assy Check that the malfunction disappear when a good air conditioning control assy is installed. Result: MALFUNCTION RESULT A Malfunction disappeared B Malfunction did not disappear B : Check And Replace Air Conditioning Amplifier A : Check And Replace Air Conditioning Control Assy