How to Test and Diagnose Electronic Control Valve (ECV) Compressor with Scan Tool 5811746

5811746 • Electronic Control Valve Compressor Diagnostic Scanner Kit

TOOLS NEEDED:

SAFETY FIRST!
Always follow standard safety precautions & use appropriate protective equipment.

PLEASE TAKE NOTE OF THE FOLLOWING BEFORE USING 5811746:

Never leave running vehicle unattended while tester is in use.
Avoid staying on manual mode for an extended period.
Keep a constant watch on high side pressure readings.
Switch from manual to normal mode if high side pressure exceeds 300psi. Failure to switch to normal mode when high side pressure exceeds 300psi can over pressurize the A/C system and damage A/C system components.
gpd recommends placing a shop fan in front of condenser during testing, especially if in hot temperature environments.

1. Identify appropriate male and female pigtails for application. Refer to Pigtail Application Chart at the end of this tech tip.

Step 1

2. Locate the compressor control valve and disconnect to connect scan tool pigtails.

Step 2

3. Connect A/C manifold gauges.

Step 3

4. Connect battery power leads. Always connect negative (-), black color, lead first. Then, connect the positive (+), red color.

Step 4

5. With engine and A/C on, check resistance on scan tool. Ideal Readings: 10Ω - 14Ω

Step 5: Press Ω CHECK RESISTANCE BUTTON to view resistance reading in ohms.

Digital display will show mode selection (normal or manual) at top of screen

In “NORMAL MODE”, the pulse width modulation (PWM) signal, shown as a duty cycle %, is received from the ECU.

Changing to “MANUAL MODE” allows for manual control of the PWM command signal to the control valve.

The interface adapter will signal PWM signal is normal with a steady green light. If the green light is flashing, there is no PWM signal from the ECU.
If the command % value is 0-20%, while in normal mode, this is a sign that the compressor is not receiving operating signal from ECU. A scan tool should be used to check system for trouble codes.
In manual mode, the PWM signal to the control valve can be manually increased/decreased. By increasing the PWM signal to approximately 80%, it can be verified if the compressor is in operating condition. If the compressor is functional when in manual mode, this indicates a failure in communication between the control valve, ECU, and/or other input signals from temperature, pressure, and refrigerant flow sensors. Otherwise, the compressor is not functional and should be diagnosed/replaced.

The “CONTROL BOX” has two LED lights (green and red).
- If green LED light is flashing: There is no PWM control signal from the ECU/ECM.
- If green LED light is steady (not flashing): PWM control signal from ECU/ECM is normal.
- IF USING 5811746 WITH A EUROPEAN MARKET APPLICATION (e.g. EU Audi) and red LED light is lit (steady or flashing): PWM signal from ECU/ECM is the wrong polarity. In these cases, a ‘reverse’ adaptor (sold separately) is required for ECU side connection.

Do not leave tester in manual mode for extended period. Switch to normal mode if high side pressure exceeds 300psi.

Control Box

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