Checking Ignition Discharge Module (IDM)

Checking Ignition Discharge Module (IDM) Power Cable
- Ignition off.
- Disconnect the ignition discharge module (IDM).
- Ignition on.
- Connect a voltmeter between ignition discharge module connector terminal 3 and ground.
- The voltmeter should read battery voltage.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check fuse 4. Replace fuse if necessary. If the fuse is OK: check cable between ignition discharge module terminal 3 and fuse 4 for an open-circuit.





Checking The Ignition Discharge Module Ground Lead
- Ignition off.
- Wait approx. 150 seconds.
- Ignition discharge module disconnected.
- Connect an ohmmeter between ignition discharge module connector terminal 1 and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is incorrect:
^ Proceed to test step below.

If reading is OK:
^ Proceed to Checking Ignition Discharge Module Control Signal section below.





Checking Ignition Discharge Module Ground Terminal
- Ignition off.
- Ignition discharge module disconnected.
- Check ignition discharge module ground terminal (31/52) for contact resistance or oxidation and remedy.
- Connect an ohmmeter between ignition discharge module connector terminal 1 and ground.
- The ohmmeter should read approx. 0 ohms.

If reading is OK:
^ The cause of the fault has been poor contact in the ignition discharge module ground terminal.

If reading is incorrect:
^ Check cable between ignition discharge module terminal 1 and ground terminal (31/52) for an open-circuit.





Checking Ignition Discharge Module Control Signal
- Ignition on.
- Ignition discharge module disconnected.
- Connect a multimeter between ignition discharge module connector terminal 4 and ground.
- Set the multimeter to measure frequency.
- Operate starter motor.
- Frequency should be 8 - 10 Hz when the engine is turned over by the starter motor.

If reading is OK:
^ Proceed to: Checking Ignition Spark From the Ignition Coil section.

If reading is incorrect:
^ Proceed to test step below.





Checking Signal Cable Voltage
- Ignition on.
- Ignition discharge module disconnected.
- Connect a voltmeter between ignition discharge module connector terminal 4 and ground.
- The voltmeter should read 0 - 1 Volt.

If reading is OK:
^ Proceed to test step below.

If reading is incorrect:
^ Check cable between ignition discharge module terminal 4 and engine control module (ECM) # B11 for a short-circuit to supply voltage.





Checking Signal Cable Resistance To Ground
- Ignition off.
- Wait approx. 150 seconds.
- Ignition discharge module disconnected.
- Disconnect engine control module.
- Connect an ohmmeter between ignition discharge module connector terminal 4 and ground.
- The ohmmeter should read infinite resistance.

If reading is OK:
^ Check cable between ignition discharge module terminal 4 and engine control module # B11 for an open-circuit.

If reading is incorrect:
^ Check cable between ignition discharge module terminal 4 and engine control module # B11 for a short-circuit to ground.