Rep Power: 0

I have a 2001 Civic LX. While I was driving this monring on the highway the green key light started flashing. And when I would turn the headlights on, or even press the brake peddle, the car's electrical system seemed to momentarily just cut out. The RPMs would drop to zero, the car would stutter, the radio cut out, and then then everything would just come back on. It would only last a fraction of a second. It did this a BUNCH of times during my 25min drive. The green key light stayed flashing the entire time. I'm not sure if I have a battery issue, a key issue, or something else. Anyone care to share some insight?

 
Rep Power: 518

Basic battery and charging system testing, cables, etc.


And make sure the alternator bolts are tight. Recent timing belt job, perhaps?

 
Rep Power: 0

I had the alternator replaced a couple months ago. My battery is pretty old too, but the connections seem tight and I was told the battery checked out fine when I had the alternator replaced.

I'm wondering if the remote key fob from my other car (2014 nissan) could be causing some sort of interference/issue here. I will try driving home with all the other keys far away from the primary honda hey.

 
Rep Power: 518

So.....Are all the bolts properly tightened?

Has that alternator failed already? (Maaaaaaybe!)


...Is it a good battery TODAY?

Battery cables have more connections than just at the battery posts. The ground cable is bolted to the transmission and body, and there's another braided ground cable between the radiator area and the engine.... The pos cable attaches to the starter, the fusebox, and the alt charge cable should be checked on the back of the alternator and at the fusebox too....
If it were interfering, the car wouldn't start and the green key light would be flashing rapidly while you crank the starter...and the engine would not run.
The Nissan key has nothing to do with todays problem. That can't make the green key light start flashing after you are driving down the road.

Low system voltage while driving could make the green key light come on though, and so could the stuff below:

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Green key light flashing while driving......
Check engine light on? Check codes but no communication?
Gauges acting screwy?
Low power and limited RPM?
Cranks but no start?

Loose alternator bolts can cause all these symptoms and more ..... including frying the engine computer.