2) Check Control Function
If vacuum is not present, with engine running, measure voltage between ECM terminal No. 102 (Red/Black wire) and ground. At idle, voltage should be zero volts. At 2000 RPM, voltage should be battery voltage. See Fig 1 . If voltage measured is not as specified, go to next step. If voltage is as specified, inspect vacuum hose for clogging, cracks or proper connection. Repair vacuum hose as necessary.