Signal Inspection Test
- Warm engine to operating temperature and allow to idle. Connect dwell meter to White check connector pin No. 1. Disconnect vacuum hose from vacuum sensor and plug hose.
- Connect vacuum pump to vacuum sensor. See Fig 1
. Apply 19.7 in. Hg. Verify dwell meter registers in the 20-70 degree range. Release vacuum. Verify dwell meter indicates a fixed zero degrees. If not, check vacuum sensor and terminal 1E voltage at ECU. See PIN VOLTAGE CHARTS and SENSOR OPERATING RANGE CHARTS articles.
- Remove vacuum pump and reconnect vacuum hose. Increase engine speed to 4500 RPM. Verify dwell meter indicates a fixed zero degrees. If reading is 72 degrees, check idle and neutral switches. If reading is other than zero or 72 degrees and other devices test within specification, replace ECU.
Courtesy of MAZDA MOTORS CORP.