Hey guys. I’m having a weird issue that doesn’t make sense to me and has me at a complete loss. I joined the forum hoping to find some help as this place seems pretty active.
Anyways I have a 86 Suzuki samurai that I have just swapped a vw 1.9 turbo diesel into with a gm 3 wire 10si 110amp alternator.
Wire number 2 is looped back onto the 12v post and has 12v at all times
Wire number 1 is hooked into my dash light. Key on engine off it reads 0v with the dash light on, key on engine on it reads just below battery voltage and dash light is off.
The 12v post is hooked into my stock wiring connected to my brand new battery.
Today I had my battery and my alternator bench tested and they both came back functioning normally.
My issue is I’m never reading above battery voltage with the engine on (either from the post on the alternator or my battery). I grabbed a used alternator locally and I was having the same issue. However with that one if I pulled the positive lead from the battery with the engine running it would read 14.3v until I would hook it back to the battery where it would drop back to battery voltage. I was able to repeat that behaviour mutlitple times until I ended up killing the alternator. My other alternator is new and I don’t wish to damage it pulling the positive lead but I’m betting it’s functioning the same way.
What in my system could be causing this? The truck is pretty old and doesn’t have a ecm or much of any eletrical and I just can’t figure out what’s going on. Its like some kind of feedback is shutting down the alternator when it gets hooked up to the battery.
So far I’ve tried temporarily adding grounds with jumper cables
Measured 0.2ohm resistance between my ground cable and the alternator housing
Measured 0.0ohm resistance between my positive lead and the 12v post on alternator
I’ve also tried pulling all the relays and accessories I’ve added to the postive lead with no change.
Any tips you guys could give would be greatly appreciated. Camping weather is quickly approaching and I need my truck back on the road!