My '99 SE has thrown the P1320 code (Ignition Signal Primary) three times in the last 10 days. The car seems to run great - runs smooth with no detectable miss.

I'm waiting on my factory service manual to arrive. Where do I start troubleshooting?

Any assistance is appreciated.

***updated***
I found the TSB section for the EGI Wire Harness Breakage Diagnosis and Repair. This looks likely. In the TSB a Black ground wire (GND-1) that goes from the engine to the ecu is referenced for code P1320. Where on the engine does that wire attach? And which ecu pin is it? I really wish that manual would arrive.

 

bump..........

 

One or more of your coil packs are going bad.

 

I considered coil packs but last time the code was thrown during braking. The car did idle rough yesterday upon cold start making me think about coils again.