Today’s Symptoms:

Tricky 2002 Honda Civic alternator problem as shown by intermittent battery light in the dash. All charging system wirings were checked OK but battery light came on every now and then. When scanned for codes, a knock sensor code was retrieved. Engine is a 1.7 L and has a 5 speed manual transmission.

Diagnostics for 2002 Honda Civic alternator problem:

This vehicle came from my friend’s garage who is too busy to handle this problem. He troubleshooted it for a day with no results but since he usually works on GM vehicles, he gave it to me because we handle Asian imports. My first instinct was to re-check the alternator voltage output including all the ground connections which were OK. We also replaced the knock sensor and cleared the code but after road testing, the intermittent battery light came back.

I was completely at a loss on what to do with this in the course of this troubleshooting. Everything checked out OK and we even rechecked the alternator mounting for looseness , pulley belt tension which were fine and installation of a new battery. Desperate for a solution and considering the electronic controls inside the alternator, we opted to replace the alternator assembly.

Final fix for 2002 Honda Civic alternator problem:

A new alternator from the dealer proved to be the solution to this problem. This was evident when we analyzed the alternator voltage graph which we ignored earlier because the voltage reading was normal. (However, a spike can be seen in the graph whenever the rpm was raised).It has been a week since the customer took the vehicle and the 2002 Honda civic alternator problem battery light did not return. Lesson learned here is not to ignore even minor glitches when testing the alternator.

Notes for 2002 Honda Civic alternator problem:

On some 2002 Honda Civic alternator problem, the alternator controller system uses transistors, diode and compact voltage regulator which can deteriorate and causes these symptoms.

As always, check battery integrity before replacing the alternator. As you can see above, we only use factory supplied alternator after getting lots of problems from rebuilt alternators.

Thanks!

Richard