The other day when I got out of work I had a strange single (so far) occurrence. I got into the Blazer (01, LT 4 door 4wd Blazer), I turned the key to run, everything looked normal, but when I went to turn the key everything died. The interior lights, guages, radio, as if the battery was unplugged (no life what-so-ever). I turn the key off, then back on and get nothing for a few seconds, then everything came on. Turned the key and everything died. I jump out of the car and open the hood just to make sure a cable wasn't loose or corroded (not really likely to be corroded as I am very paticular about my vehicles and you could eat off of the battery), but everything is snug and clean. While I am looking at the battery (before I had even touched it)I noticed the light under the hood had suddenly come on. I close the hood and jump back in the truck, turn the key and everything lights up as normal, voltage on the meter and my volt meter on my radar detector both say 12 volts, so I turn the key and the lights dim, the truck struggles, butcranks and runs very rough (like a vacuum hose is disconnected) at around 400rpm's and is stuttering. I rev it a little, seems likeI canhear a miss soI shut it off. Everything still looks normal on the dash, I crank the truck back up and all has ran right since. Voltage is spot on while operating and doesn't fluctuate much, nor has it ever since I got it and everythingseems to berunning normal.


So to me this seems like a possible PCM issue, but I haven't seen a PCM cause all 12 volt power to be cut from the vehicle. I can understand some, but I figured Constant 12 volt going to the radio (for settings) shouldn't have been bothered if it was the computer. I have thought aboutthe securityfeatures doing it (stock alarm) ormaybe it's the battery showing me it's first signs of dying, the battery looks brand new, but I bought the Truck in August so I don't know how old the battery is. But for power to kill off flat like that when the meter had shown 12 volts right before makes me feel the battery is fine.


Anyway, maybe it was a one time thing, but figured I would throw it out here just in case it is a precursor to something that has been experienced.

 

The PCM has very, very little to do with the actual operation of the starter. By your description, you had a high current draw that killed everything while you had the key turned to start. This to me points directly at the battery. Is your battery the original AC Delco battery? The AC Delco batteries used in these trucks (and quite a few others) have a tendancy to corrode INSIDE the positive terminal. My battery looked brand new in my Bravada, but one morning I jump in it and the exact same scenario played out. Got out the jumper cables and hooked up my Bonneville and it started right up and continued to start up with out issue for 5-6 attempts right after (I wasn't in a hurry). When I attempted to remove the battery cables from the battery to make sure everything was clean, the positive post (the whole darn thing) came right out of the battery, spilling battery fluid all over. It was a mess inside with no visual cues from the outside.

Just something to check.

 

Good advice. I have a spare battery that came out of the Z when I put in a Yellow Top, so I will probably throw it in this weekend just to be safe. At least it would be a cheap fix.

 

check the screw on the positive side of the battery take it out and see if it is stripped. i just had that happen to me. I replaced my alternator thinking that was the problem but it was just that screw that holds the positive cable onto the battery. autozone = $1.99 for 2.

 

This morning it did the same thing. I waited a short time, but the truck never came back to life and since I was already late for work, I hoped in the Z and went on my way. The spare battery from the Z sitting at the parents house, so I called dad and told him to throw the Charger on it. I will pick it up on the way home and start messing with the battery in the truck.