Out of the blue yesterday, the MIL on my 2005 ES330 lit up on my way home from work. The car was, and has been running fine. I continued home (about 20 miles) and checked the code. P0351, P0352, P0353, P0354, P0355 and P0356 were specified, indicating malfunctioning ignition coils in all cylinders. Again, the car was running fine. About a minute after I turned off the car and closed the doors I heard an electrical humming sound coming from the engine compartment. I also noticed the MIL was on (it went off when I turned-off the car). When I opened the door, the MIL went out and the hum stopped. I closed the door and the hum started again after a few seconds. Seemed the hum started at the same time the alarm system was armed. Opened a door and it stopped. I decided to leave a door ajar overnight and contemplated clearing the codes. This morning the car started and ran fine, so I cleared the codes. Drove to work (about 60 miles) and the MIL did not come back on. I parked and locked the car. When I left work at the end of the day, the battery was dead. BTW, the battery is only a few months old and has had plenty of juice. The MIL was illuminated again. Based on what occurred the night before, I’m thinking whatever was running (humming) started some time during the day and drained the battery. Anyway, I got a jump-start and drove home. The MIL did not come back on and so far, everything seems normal.
No doubt, something is wrong, but the behavior seems awfully strange. Anyone ever heard of such a thing, and what the cause might be?

 

Get your battery tested and make sure your alternator is working properly. The primary ignition system relies on the charging system to work efficiently. If you got weak juice from the battery, you will get low feed to the primary ignition system and it will not have enough voltage to feed the secondary ignition system.

 

Thanks for your response GS4_Fiend.
I believe I found the culprit. I found the ground wire from the bypass module for my remote start got loose. I reconnected it several days ago and the problem hasn't recurred. Hopefully it won't!

 

thats why i don't have aftermarket remote start......
even though i could use it since it gets cold as ***** here.

 

What about the engine light? What was the code, you should retrieve it.

 

I believe the MIL was a side-effect of the loose ground wire; it hasn't come back on since the wire was reattached. It had been throwing P0351-P0356 codes, but all is well now. Thanks for checking back.