Disconnect the upper solenoid valve vacuum hose from the vacuum manifold and connect the vacuum pump.
Plug the end of the #32 hose.
Warm up the engine to operating temperature until the cooling fan turns on.
If the solenoid valve holds a vacuum, then see item A), if not holding, then item B).
A) Disconnect the 4-pin connector near the solenoid valve.
Measure the voltage between White/Yellow (+) and Cherny (-) contacts on the main wiring harness. If voltage is present, refer to the control module input diagnostics section.
If there is no voltage, then the solenoid valve should be replaced.
B) Bring the engine speed up to 2500 rpm and create a vacuum.
If the solenoid valve is holding a vacuum, then check the vacuum line for proper connection, cracks, blockage, or hose disconnection.
If the solenoid valve does not hold vacuum, then disconnect the 4-pin connector near the valve.
Next, measure the voltage between White/Yellow (+) and Cherny (-) terminals on the main wiring harness while the engine is running at approximately 2500 rpm.
If battery voltage is present, the solenoid valve should be replaced.
If there is no voltage, then measure the voltage between White/Yellow (+) contacts and ground while the engine is running at approximately 2500 rpm.
If there is battery voltage, then the break in the Black conductor between the control box and point G5 should be repaired.
If there is no voltage, then you should check for an open White / Yellow wire between the control box and terminal 20 of the control unit. If the wire is normal, then you should refer to the diagnostics of the inputs of the control modules.