Diagnostic Tools
- Tools necessary for diagnosis are a dwell meter, tachometer, test light, digital volt/ohmmeter, vacuum pump, vacuum gauge, jumper wires, and connector tool (J-28742) to remove terminals on Weather Pack connectors.
- A test light, rather than a voltmeter, must be used when indicated by diagnostic chart.
- A dwell meter is used to measure the time that the vacuum control solenoid solenoid is on or off. This gives an indication of how the system is working and how rich or lean the mixture. Set dwell meter for 4-cylinder scale.
- Dwell meter positive lead is connected to the bright green connector in the wiring harness, near the vacuum control solenoid. Connect the negative lead to ground. DO NOT
allow terminal wire to come in contact with any ground source, including rubber hoses.NOTE: If engine operation changes when dwell meter is connected, remove dwell meter and try another model. A few brands are not compatible with the electronic emission system.
- When engine is at operating temperature and idling, dwell meter needle will move up and down scale. This indicates the system is in closed loop operation. If the needle does not move, the system is in open loop operation.