2003 Civic ABS/Brake/Airbag Indicators & das light issues

The widespread electrical symptoms suggest you have something wrong in the main electrical system. That usually means one of three areas: alternator, battery, or connections (especially ground connections). Are you looking at a DIY approach or at what to expect when you take it to a shop?

Mike

If you have a digital voltmeter you can check a few important things.

With the engine running (since that is when you have the problem) and the headlights on measure the DC voltage between the engine block - anyplace on the engine, actually - and the chassis. There should be negligible voltage between the two. If there is voltage the engine ground is not connected and that will certainly cause all sorts of weird symptoms.

Also with the engine running, check the DC and AC voltages across the battery. The DC should be 14 volts +/- about 1/2 volt... higher when the alternator is cold, lower when it is hot. The AC voltage across the battery must be less than 0.1 volt. If it is higher - often over a volt AC - either the battery is seriously bad or the alternator has bad diodes. Replacing the battery or even connecting another one across the existing one with jumper cables will tell the difference.

If that doesn't show anything obvious, you are probably going to have to verify grounds behind the dash and probably under the hood. That is much more easily done with a Helm manual (about $60 US IIRC from Helm