'99 PSD Engine Eletrical Issues/Won't Start
Hello all, hope you can help with this electrical issue I am having. I have an early 99 PSD all stock except the stereo head unit. About four days ago while driving on highway battery light came on. Voltage reading was normal and the truck ran fine.
Next morning when I turned the key to the on position noticed that the battery meter dropped to around 8V immediately. Went to start, the engine would turn over but very slowly and would not start. Went to get batteries checked and found that they both were at about 17% charge. Charged both and the main failed the load test. I replaced it with the same Cold Cranking Amps and Voltage. Put batteries back in after thoroughly cleaning the posts and terminals. Started truck and battery light was still on. Checked the charging voltage of the Alternator and it was coming in at about 11.5 on both batteries. Swapped with a known good alternator from my dads '00 PSD X and got same results. My alternator worked fine on his as well. Ran truck around that day with no starting issues. However it did not sit more than an hour between starts.
Go back out this morning, turn key to on and battery meter was again extremely low (4-6 range). Truck would not even turn over. Looked at fuses in dash and they were all good.
Fuses under the hood were different. I found 4 bad fuses (#3, 4, 10, 16) according to the owners manual, they all deal with some aspect of towing/trailer wiring. #3 was "Trailer Tow Right Stop/Turn Lamp", #4 was "Trailer Tow Backup Lamps, Trailer Tow
Park Lamps", #10 was "Power Point", and #16 was "Trailer Tow Battery Charge".
The only other things I saw were the battery cable running from the main to the aux had some corrosion where it enters the positive lug on the main battery.
I am fairly ignorant when it comes to electrical systems, I know just the basic functions of a multimeter and resistance checking.
So here are the questions... Could the trailer wiring issues be causing the drain on the batteris(if there even is one)? Could they also be responsible for the low charge voltage coming from the alternator? Could it be a combination of issues that all happened at the same time? Where do I start troubleshooting?
Thanks in advance for any advice or help...