Intermittent charging system problem
i have another problem to resolve with my 2005 high mileage malibu LS v6.
Three times it has shut down on the road,with abs warning, then loss of power steering, then lockdown to 5mph,then stop engine,all happening over about 10 seconds. On each occasion, the battery was dead. The dealer'* very experienced mechanic narrowed it down to computer shutdown due to no electric power. This seems very reasonable. The dealer tested the battery, told me to replace it, and I did, with a new one. It has done the same thing twice since that. A voltmeter plugged in to the cig. lighter shows its charging intermittently,whn I get above 12 volts, it stops charging often. Sometimes shutting off the engine fixes it for a short while.it never makes it to 14 volts.
I tested the voltage at the alternator, same as at the + battery terminal.there is only one other wire to the alternator, I can't find out whether it is a field wire,or a signaling wire to turn on the alternator. It has about 4.5 volts dc on it when ign on and car running. I connected an oscilloscope, and there is no ac or digital signal evident,and the only other thing seen is a bit of ignition hash picked up from the nearby distributor.. I currently have a brand new alternator installed, with absolutely no improvement.
I need to know where this small wire comes from, and what kind of signal it should have. I want to check continuity of the wire. Could it be a problem with the computer? The only code stored after one of the three shutdowns was lean condition, probably irrelevant.
Does anyone know where to look next? I am putting on a new serpentine belt next.its quite old, but I don't think it'* slipping.
Last edited by Ralph Lewis; 11-07-2014 at 09:43 PM.
Reason: found a misspelled word