I removed the ignition module to check the spark plugs. Noticed the headlights were on, then a short time later the horn start honking. Disconnected the battery for awhile. No fix. Any ideas on how to get it to stop.

Thanks in advance.

That's a good one. No idea. Sounds like your alarm went off because the ignition module was removed.

I don't think 98 Malibu had a factory alarm system so this is likely aftermarket. Unfortunately who knows how they might have wired it up. :(