Charging intermittent, sometimes it does sometimes not

CHECKING FOR VOLTAGE DROP

Once you have fixed the basic "no charge" problem, time to check for system voltage drop to make sure it will not over charge (over voltage).

Turn key to "run." Connect meter to "as close to" VR IGN terminal as you can without disconnecting wiring. This is likely the IGN terminal on the ballast resistor. Stab other probe into top of battery + terminal. You should read very little voltage, the less the better. If you read more than .3V (3/10 of 1 volt) you need to chase down why. Typical drop is in the bulkhead connector terminals, the ignition switch connector, or the switch itself

ONE WAY to "fix" this problem is to add a relay for underhood "ign run" loads. Electrically cut the (usually) dark blue "ign1" "Ignition run" wire coming out of the bulkhead. use the bulkkhead end to trigger a relay, and connect the remaining cut end to the relay load contact. Feed the relay contacts with power/ fused/ breaker off the starter relay "big stud." Ground the remaining relay coil. You can feed this through an unobtrusive switch for an 'easy" anti-theft switch

VR GROUND. The VR ground path can have voltage drop as well. To check, do this:

Run this test with engine running at "low to medium cruise" (fast idle) and with battery/ engine warm and normal. Run test first with all loads off, and again with heater, lights, etc, turned on

Stab one probe into the VR mounting flange. Stab the other into the top of battery NEG post. As before, you are hoping for a very low reading, zero is perfect. If yourread more than .2--.3V improve the grounding from battery/ engine/ firewall.

A good way to do this is to buy a short starter cable, "eyelet to eyelet." Look at your pass front head (v8) The same holes are on the REAR of the driver's head. Use a short bolt, connect the cable back there. Connect other end to good solid bolt through firewall, or to one master cylinder mounting stud.