I have a 1998 Chevy Blazer 4.3L 4X4 that I did a motor swap in. The motor is out of my old 1996 GMC Jimmy. After the swap I was able to start it and run it with no problem. Now all of a sudden the motor won't attempt to turn over. I tapped on the starter and it finally turned over and started so I figured it was a bad starter. I replaced the starter and went to start it again and have the same problem. Motor won't attempt to turn over. No clicking nothing. I found an aftermarket alarm system in the vehicle so I took it completely out and it finally started. I drove the blazer for an entire day stopping it and restarting it multiple times. The next day I went out to start it and its back to doing the same thing. Motor won't attempt to turn over. I have a new battery, new starter and new crank sensor and all the grounds appear to be good. I am lost on what to do next.

 

You need to do a test for parasitic draw on your battery. Start by charging the battery if it has drained. Set up your DMM for Ammeter function (red lead on left). IMPORTANT! After the test insure you remove the red lead from the left side and put it back on right side. If you forget you could fry something else you test because while on left side your DMM is basically a jumper wire. Disconnect the negative battery cable and connect DMM leads in series between B- terminal and B- cable. There's a small computation based off of reserve capacity of your battery, but basically if there is a a draw above 50mA you have something that is drawing juice when truck is off. Couple notes, disconnect the under hood light and wait over 20 minutes before recording your reading. It takes the PCM that long to go back to sleep. Don't open any doors or anything because that will wake the PCM up. Also make sure you don't have anything plugged in to your cigar lighters.

NOTE: I'm assuming your DMM is like mine with the ammeter socket on the left like mine. I'll leave it to you to verify on yours. Black lead of course goes in "Com" socket.

 

Thanks I will try it and see what happens. When the aftermarket alarm was installed they spliced into the ignition starter switch. Could that have been damaged by them doing so?

 

Definitely could have been. Those switches are known to go bad without anyone touching them. The fact that when you put a new battery in and it worked for a day then quit is what would lead me to the parasitic draw test. Maybe before doing that you might want to do a voltage drop test on your battery cables. Look for a you tube video on how to do it. Really simple. Dan Sullivan has a good one.