Ignition System: Testing and Inspection

Ignition Coil Relay Circuit Troubleshooting

1. Check the No. 18 (15 A) fuse in the under-hood fuse/relay box.

Is the fuse OK?

YES -

Go to step 2.

NO -

Replace the fuse. If the fuse continues to blow, locate and repair the short in the circuit between the under-hood fuse/relay box and the ignition coils.�

2. Remove the ignition coil relay from the under-hood fuse/relay box, and test it Testing and Inspection.

Is the relay OK?

YES -

Go to step 3.

NO -

Replace the ignition coil relay.�

3. Measure the voltage between ignition coil relay 4P socket terminal No. 2 and body ground, then terminal No. 4 and body ground.





Is there battery voltage?

YES -

Go to step 4.

NO -

Replace the under-hood fuse/relay box.�

4. Check for continuity between ignition coil relay 4P socket terminal No. 1 and No. 1 ignition coil 3P connector terminal No. 3.





Is there continuity?

YES -

Go to step 5.

NO -

Repair an open in the wire between ignition coil relay 4P socket terminal No. 2 and ignition coil 3P connector terminal No. 3.�

5. Connect the HDS to the DLC Initial Inspection and Diagnostic Overview.

6. Turn the ignition switch to ON (II).

7. Make sure the HDS communicates with the vehicle and the PCM. If it does not communicate, troubleshoot the DLC circuit Testing and Inspection.

8. Jump the SCS line with the HDS, then turn the ignition switch to LOCK (0).

NOTE: This step must be done to protect the PCM from damage.

9. Disconnect PCM connector A (44P).

10. Check for continuity between ignition coil relay 4P socket terminal No. 3 and body ground.





Is there continuity?

YES -

Repair a short in the wire between ignition coil relay 4P socket terminal No. 3 and PCM connector terminal A6.�

NO -

Go to step 11.

11. Check for continuity between ignition coil relay 4P socket terminal No. 3 and PCM connector terminal A6.





Is there continuity?

YES -

The system is OK at this time. Check for loose or poor connections at the ignition coil relay and the PCM connector terminal A6. If you have a no-start condition, update the PCM if it does not have the latest software PCM Update, or substitute a known-good PCM Initial Inspection and Diagnostic Overview.�

NO -

Repair an open in the wire between ignition coil relay 4P socket terminal No. 3 and PCM connector terminal A6.�