apt10

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Car is 2004 civic ex 5 speed with 98k miles

Battery was replaced by previous owners in 2009. Stock alternator with 98K miles on it. The grounds look fine and tight.

Everything works fine at idle. At higher rpms is when this problem occurs. Does not happen all the time but pretty intermittent.

What do you guys think? Where should I start? The multimeter is not sensitive enough to pick this up.

If this is the alternator what is the best source to pick up a good one?

ezone

You need a meter that is able to react much faster. One that has MIN/MAX record capability, or a labscope.
I may use the labscope and check for voltage drops while it is running and acting up, and the PCM control of the alternator/regulator charge command.


When did this start acting up? Any work done immediately prior to this? Timing belt job?

I'd guess that's about a 2V pulse, and I'd start with checking that the alternator bolts are tight. Loose mounting bolts leads to overvoltage and burning up the PCM.



If it does turn out to be a bad alternator, I'd use a factory reman. Aftermarket is always a crapshoot, and not something to depend on for reliable transport. (The cars really don't like cheap crap parts.)



Autozone: Turning your Honda into a Hyundai one part at a time.




HTH