I just picked up a 2001 express2500 when the tranny went in my last 1. I was going to salvage the transmission but found out this has only 18k on trans and 46k on a new jasper engine. The receipt shows the ECM as being replaced along with transmission. So I buy it after it sat for 11 months untouched. Battery was dead and turned out starter also. Replaced starter and battery it fired up ran great for 2 weeks. Random times security light came on but ran fine. No security stays on steady but cranked forever before it will run and runs ****ty. Any suggestions on where to start looking?

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