Pinout Values and Diagnostic Parameters
ECU Pin Voltage TestingFAULT FINDING.
WARNING: The microprocessor is an extremely sensitive and expensive unit, and should only be tested using a digital type multi-meter with no less than a 3.5 digit display, and a resistance of no less than 2 megaohms any other form of multi-meter will irreversibly damage the microprocessor.
The control pins are mounted very close together, therefore, there is a high risk of shorting two pins together when using a test probe.
Two pins shorted together even momentarily, will cause irreparable damage to the control module.
To avoid shorting two pins together an insulated sleeve or shroud must be fitted over the probe so that it overlaps the end of the probe by approximately 3 mm. The insulation stripped from a piece of cable will provide suitable sleeve.
Always allow time for servos to come to rest.
Automatic check will require setting all sensors to known condition, ie in workshop area at 24°C (75°F) for at least 30 minutes.
Sensor inputs will relate to ambient temperature, ie at 24°C (75°F), sensor voltage readings will be 2.97V (10mV= 1°C (33.8°F)).
SYSTEM OFF
POWER SUPPLY ON
Pin No Voltage
Ignition in 1 11 - 14V
Recirc Input 9 2 - 6V
Grounds 2 0 - 40mV
6 0 - 40mV
10 0 - 40mV
38 0 - 40mV
45 0 - 40mV
From On/Off Switch 44 0 - 12mV
To On/Off Switch 12 10 - 13.3V
Set in Manual by shorting pin 19 To Ground
SELECT LOW ON MODE SWITCH
MAXIMUM TEMPERATURE DEMAND
Low Input 13 150 - 350mV
Clutch Output (Evap Sensor
below 2.720V) 20 0.6 - 11.4V
Medium Input 14 3 - 5V
High Input 15 3 - 5V
Defrost 27 3 - 5V
From On/Off Switch 44 10.3 - 13.3V
Output 43 4.73 - 5.2V
Recirc output 3 0 - 200mV
High Speed Relay 16 0 - 200mV
Water Valve Vacuum Solenoid 17 0 - 200mV
Centre Vent Vacuum Solenoid 18 0 - 200mV
SELECT NORM (MED OR AUTO) ON MODE SWITCH
Low Input 13 3 - 5V
Medium Input 14 150 - 350mV
High Input 15 3 -5V
Defrost Input 27 3 -5V
SELECT HIGH ON MODE SWITCH
MAXIMUM TEMPERATURE DEMAND
ENSURE SERVOS ARE STATIONARY
Low Input 13 3 - 5V
Medium Input 14 3 - 5V
High Input 15 150 - 350mV
Defrost Input 27 3 - 5V
SELECT DEFROST
Low Input 13 3 - 5V
Medium Input 14 3 - 5V
High Input 15 3 - 5V
Defrost Input 27 150 - 350mV
TEMPERATURE & DIFF POTERTIONMETER RANGES
Temperature Demand (Maximum) 35 2.665 - 3.105V
Temperature Demand (Minimum) 35 0 - 200mV
Diff Demand (Maximum) 28 4.750 - 5.250V
Diff Demand (Minimum) 28 0 - 200mV
Set Temperature Demand to
Mid Range 35 1.43 - 1 .45V
SELECT NORM
Recirc output 9 3 - 5V
Servo Drive Lower Flap 37 4V
Servo Drive Lower Flap 41 4V
Servo Drive Upper Flap 40 4V
Servo Drive Upper Flap 42 4V
Recirc output 3 0 - 500mV
Reference voltage 7 2.875 - 2.895V
Defrost Output 11 0 - 500mV
High Speed Relays 16 0 - 5OOmV
Lower Feedback Potentiometer 29 0.60 - 0.90V
Upper Feedback Potentiometer 30 1.15 - 1 .45V
Coolant Temperature Input 21 260 - 460mV
Defrost Output 11 0 - 500mV
Clutch Output (Evaporator
above 2.745V) 20 10.3 - 13.3
RH Blower Feedback 33 10 -13V
LH Blower Feedback 22 10 - 13V
RH Blower Control 32 0 - 0.5V
LH Blower Control 31 0 - 0.5V
Water Valve Solenoid 17 0 - 500mV
Centre Vent Solenoid 18 0 - 500mV
SELECT LOW ON MODE SWITCH
MAXIMUM TEMPERATURE DEMAND
Set Diff to Mid Range 28 2.45-2.55V
Servos Stopped 37 0 - 40mV
40 0 - 40mV
41 0 - 40mV
42 0 - 40mv
Lower Feedback 29 0 - 0.2V
Upper Feedback 30 0 - 0.2V
Set Temperature to Mid Position 35 1.43 - 1.45V
Servo Stopped 37 4V
40 4V
41 4V
42 4V
Lower Feedback 29 0.57 - 0.87V
Upper Feedback 30 0.60 - 0.9V
Set Temperature to Maximum 35 2.665 - 3.105V
Lower Feedback 29 0.979 - 1.279V
Upper Feedback 30 1.518 - 1.818V
Set Diff to Maximum 28 4.750 - 5.20V
Lower Feedback 29 0.979 - 1.279V
Upper Feedback 30 1.340 - 1.640V
BLOWER TEST
Set Diff To Minimum 28 0 - 200mV
Set Temperature to Minimum 35 0 - 200mV
Note: After setting allow servos to come to rest. Typical voltage figures are in the brackets.
Mode Switch RH Control LH Control RH Feedback LH Feedback
Position Pin No 32 Pin No 31 Pin No 33 Pin No 22
Low 1-2V (1.77V) 1-2V (1.7V) 4-6V (5.8V) 4-6V (5.63V)
Med 2-3V (2.28V) 2-3V (2.27V) 3-5V (3.7V) 3-5V (3.4V)
High 1-2V (1.17V) 1-2V (1.19V) 1-2V (122V) 1-2V (1.27V)
Pin No Voltage
Set Temperature to Mid Point 28 1.43 - 1.45V
Mode Switch RH Control LH Control RH Feedback LH Feedback
Position Pin No 32 Pin No 31 Pin No 33 Pin No 22
Low 1-2V (1.24V) 1-2V (1.27V) 6.5-9V (8.7V) 6.5-9V (8.7V)
Med 1-2V (1.4V) 1-2V (1.41V) 6.9-9V (7.5V) 6.5-9V (7.5V)
High 2-3V (2.2V) 2-3V (2.2V) 3-5V (4.1V) 3-5V (4.0V)
Pin No Voltage
Set Temperature to Maximum 28 2.88 - 3.10V
Mode Switch RH Control LH Control RH Feedback LH Feedback
Position Pin No 32 Pin No 31 Pin No 33 Pin No 22
Low 1-2V (1.67V) 1-2V (1.63V) 6.5-9V (6.25V) 6.5-9V (6.1V)
Med 2-3V (2.17V) 2-3V (2.1V} 3-5V (4.25V) 3-5V (4.2V)
High 2-3V (2.3V) 2-3V (2.3V) 3 -5V (3.7V) 3-5V (3.5V)
Pin No Voltage
OPEN THE WATER TEMPERATURE SWITCH LEADS
Set Temperature to Mid Point 35 1.43 - 1.45V
RH Control 32 0 - 0.5V
LH Control 31 0 - 0.5V
SHORT THE WATER TEMPERATURE SWITCH LEADS
SELECT LOW ON MODE SWITCH
Clutch Output 20 9.3 - 12.3V
RH Control 32 1 - 2V
LH Control 31 1 - 2V
Set Diff to Minimum 28 0 - 200mV
Set Temperature to Minimum 35 0 - 200mV
Recirc Output 3 9.3 - 12.3V
High Speed Relays 16 0 - 200mV
Water Valve Solenoid 17 9.3 - 12.3
Centre Vent Solenoid 18 9.3 - 12.3
Defrost output 35 0 - 500mV
Select Defrost On Mode Switch 27 150 - 350mV
High Speed Relays 16 9.3 - 12.3V
Lower Feedback 29 2.709 - 3.100V
Upper Feedback 30 1.714 - 2.014V
Select Off On Mode Switch 44 0 - 1V
Recirc Output 3 9.3 - 12.3V