Coolant Vacuum Switch Three Port (CVS3P) Diagnosis

1. Ensure engine temperature is below 125°F, then disconnect vacuum harness from the CVS3P valve.
2. Connect suitable hand vacuum pump to the top nipple on the valve, then apply vacuum.
3. If valve does not hold vacuum, proceed to step 4. If valve holds vacuum, replace valve.
4. Allow engine to reach normal operating temperature, then apply vacuum to the top nipple of the valve.
5. If the valve holds vacuum, valve is satisfactory. If valve does not hold vacuum, replace valve.