Why would a G20 not charge after replacing the battery and alternator with new ones?

Answer 1

The clip on the alternator , it has a flat rectangle look, two wires . Often the wire on one of the clips will break, come loose, and still look ok. Carefully look to see if the wire is flexing thru the soft covering of the wire insulation, but broke inside. ( Very Common) Looking at the plug , has it a melted appearance to the plastic rectangle. Can you see the shiny copper/brass contacts that clip to the flat ears of the alternator. If that plug looks cooked, buy a replacement and carefully cut, splice , solder the new plug to the two wire harness you cut the old plug from. GET THE WIRES RIGHT ! You should also check the big red wire bolted to the backside of the alternator. ( usually has a rubber cap that covers the nut and stud it is bolted to.) Follow it along its path from the alternator, to the firewall you will see it attached to a block on the firewall . Was the wire soft and extra flexable along its path? You are looking for a melted internal wire. If you find a break or melted area internally along the wire...it may be the fuseable link. It is designed to melt if too much voltage ( an alternator shorts out or a battery shorts out)is loaded on the circuit. (Keeps it from causing a FIRE) You will often see that the wire has a Black or Red Plasic bulge built into the wire covering. This is the mark of a fusable link. REPLACE THE ENTIRE LENGTH with a NEW FUSABLE LINK...DO NOT SPICE IN A REPAIR. You may see a burned or discolored area in the wires outer vinyl covering. ( Not the Black PLastic outer , split protector cover....but the wire itself. Peel it out of the split covering if it is in one. If it is firm , look at the wire from the block on the firewall to where it runs. Did you recently change a Starter? Check the battery cables, are there any wires loose ( not connected) in the area of the battery? Have the parts store recheck the alternator..if it is a rebuilt...it may be bad. It happens more than it should. Post again here if you do not find an obvious problem. I have never seen both a bad Battery, and a Bad alternator on the same car. They work in the same circuit on the car...but usually only one will fail causing the loss of charge. Not at the SAME TIME. You have changed the major parts...but that may not have been the problem. Let me know what you find.