I have an 02 Trailblazer LTZ with an inline V6. I’ve replaced the starter, alternator, 6 spark plugs, battery, internal AC control, thermostat, and the belt is fairly new and in good condition. Now, it has issues starting at any temperature, acting as if the battery is dead. The first crank does nothing, but immediately after the failure, it will start, though the radio resets to 12 and the AC cuts on. I’ve tried pulling all the AC and radio fuses, but no luck. Any suggestions? Also, it sounds like a late 90s light-duty diesel while running.
It sounds like you might have an issue with the ignition switch or wiring. The fact that everything resets suggests a possible electrical problem. Have you checked the battery terminals for corrosion or looseness?
You should also check the ground connections. A poor ground can cause all sorts of starting issues. Make sure the ground strap from the engine to the chassis is secure and clean.
Consider testing the battery under load. Sometimes a battery can show good voltage but fail under load conditions. If it’s older or has been drained multiple times, it might be worth replacing again.