2003 4WD Blazer ZR2 Auto

Major no-start condition and have no clue where to even start to find the problem. The story so far:

Everything began as a problem with the vehicle cranking but not turning over during or immediately after rain, but it would start normally after about a day of dryness. This time, however, several days later it still wouldn't start. It was acting as if the battery were run down.
I took the battery to get checked. I was told it tested fine and they charged it up. Reconnected it, but still no dice. With some research, I was pointed to the coil as a likely point of trouble when having difficulty starting after rain, but that was dry and was not arcing. Next up to check was the distributor cap and rotor, and sure enough, the contacts were gummed up white with corrosion and the copper on the rotor had a green film. I replaced the cap and rotor and was able to start the car almost immediately. I let it run for about 15 mins then turned it off.

The next day, with no further rain, it wouldn't start again. The new cap had come with screws that were too long, and the cap wasn't firmy secured, so I ordered OEM screws (had lost the originals when removing the old cap and rotor). When I received those I secured the cap down properly, but it didn't help. I put a booster pack on the battery just in case, but it made no difference either. As best I can describe, it acts as if something is not getting sufficient power from the battery. When turning the key the battery light comes on, but it does not crank whatsoever. Just completely silent. Additionally, with or without the key in the ignition, I hear a faint clicking every few seconds from under the dash, coinciding with a couple of gauges jumping, then dropping again with the next click. Over and over. Sometimes the security light flashes.

Could this be some kind of security ignition feature (stock factory security system)? Where else would I even start to look? I've never encountered this before.

 

It gets worse.

I just tried to check if the vehicle was drawing enough power to operate windows, etc with the key in the on position, without cranking. The doors unlocked with the remote fob, although much quieter than usual. With the key in the on position, the battery light would not come on, but it would flash if you tried to crank. Unable to roll windows up or down in any position. I even tried to check for codes but with the key in ON position, it couldn't connect to the scan tool.

And now I am unable to remove the key from the ignition. It just won't let go of it. A little Google-Fu and I found out about the hidden release button and was able to get the key free. I'm told this happens when the battery is dead. The battery should not be dead, BUT. . . it's a Walmart battery, it's in the final month of it's full replacement warranty, and there's always a chance they lied about testing it because they didn't want to replace it. Other than that, I don't have a clue.

 

Went with my gut and swapped the battery for a new NON Walmart battery. Put it in, started right away. So it's either a faulty battery that couldn't hold a charge or something else was putting a drain on it. Just to be safe, I'm leaving the new battery disconnected overnight and tomorrow will drive it to get the alternator checked.

 

Grab a meter and measure the resting battery voltage and the battery voltage during a failure to crank. Then when the truck is running monitor the battery voltage. If you suspect a parasitic drain problem then we can launch into that issue. A properly charged battery with the surface charge knocked off (20 seconds of headlights) should have a resting voltage of 12.6 volts.

George

 

Here is a voltage vs state of charge chart:





George