I built a 41 Chevy pickup with painless wiring harness, OBDII 2002 0411 engine harness conversion. I have this problem of the truck not showing charge for about the first 20 minutes I drive it, maybe 15 min in warmer time and little more than 20 as cold weather is coming on now. After that time period, voltmeter shows 12.5 to 13 volts.
When it if first started it shows about 10.5 volts until that time period.
I used the painless harness normal way to wire up alternator, and disabled all the charging section of the 0411 ecm, and left those wires out of OBDII part of harness.
I am using 92 Camaro front serpentine system with the thirdgen alternator.
I even removed alternator and had it tested and it tested just fine. I then removed alternator I know is fine from another car and switched them. Same thing with truck and the one from truck worked fine on other car.
Any ideas?
I've been doing this a long time, and never ran up on this qwerk before.
Thanks guys.