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I have a Chevy Astro Van that I use to haul bulky or heavy things and to pull a trailer. It usually goes less than 1000 miles a year and for the past couple of years most of that was doing drive cycles in an attempt to get the I/M "ready". It sits for long periods particularly in the winter and if the battery gets low the readiness needs to reset. In the past it has reset after a few hundred miles, some of which was the recommended "drive cycle protocol". It was always the CAT monitor.
This year the CAT did not clear after 500 miles. No codes, stored or otherwise, and no CE light ever. My local inspection station could only recommend keep driving. In desperation I went to the Chevy dealer and they cleared it the same day.
It seems that the problem was a loose plug-in connection on the alternator. I'm no EE and I can't get my head around that at all. If a voltage spike, why only the CAT? I did replace the alternator a couple of years ago, so I am responsible for the loose plug but the issue was going on before that, although it would clear after a couple of hundred miles before this year.
Problem solved for now but I am completely baffled as to what went on.
Any ideas, wisecracks, jokes or theories will be appreciated.
Tom
This year the CAT did not clear after 500 miles. No codes, stored or otherwise, and no CE light ever. My local inspection station could only recommend keep driving. In desperation I went to the Chevy dealer and they cleared it the same day.
It seems that the problem was a loose plug-in connection on the alternator. I'm no EE and I can't get my head around that at all. If a voltage spike, why only the CAT? I did replace the alternator a couple of years ago, so I am responsible for the loose plug but the issue was going on before that, although it would clear after a couple of hundred miles before this year.
Problem solved for now but I am completely baffled as to what went on.
Any ideas, wisecracks, jokes or theories will be appreciated.
Tom
