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Background:
For some reason, my headlights were on when the car was off. I tried to start the car, the battery did not have enough juice to crack it. So I jump started with 08 Toyota Highlander. I was in a hurry and did not pay attention, I connected positive terminal from highlander to negative terminal on the LS. I didn't realized I f'ed up until the jumper cable was smoking and got super hot. I immediately disconnected the cable. I took the battery to an auto parts store and the battery checked out okay. They put the battery on slow charge for overnight.
Issues:
I reinstalled the recharged battery and I don't have any power in the car. ZERO. NONE. So I researched the web and the forum for an answer. I tested the fuses with FLUKE multimeter on 40A AM1, 80A Main, Engine Main, and Starter Fuse. I connected the negative prong to battery's negative terminal and the positive prong to fuses to test resistance. They turned out ok. I used FLUKE multimeter to test the fuses circled in red
I repeated the process with other fuses and found some fuses have no resistance but when I tested individually, they are ok. The area highlighted have no power (resistance). Is this a significant finding that I need to get resolved?
I have not test any relays. If I need to, what relay should I test?
I also cleaned the positive terminal in case they were too corroded.
Check the continuity between the battery post + and the B terminal of the alternator using a multimeter. You need to access the B terminal from under the car.
I took relays out from the fuse box and I was stunned to find my fuse box to be BURNT. I didn’t have the time to check relays but looked burnt too. So should I buy a new fuse box from the junkyard and replace it or do I test it to see if salvageable. Dang relays cost $25 a piece from autozone.
Your problem happens when the jump cable is not thick enough or the alligator clips have some resistance. Due to the resistance and the limitation of the current, the 120A ALT fuse does not open quickly and the big current continuously goes through the alternator via that fuse. At the same time, the negative voltage is applied to others. These cause one or more of following problems.
1, Serious damage between the battery post + and the B terminal of the alternator line by the heat. (mostly the connecting points)
2, The rectifying diodes in the alternator are damaged.
3, The negative voltage damages some equipments connected.
The initial burnt was started from the 120A ALT fuse line. To fix this is the important first step. What comes next? There are a few more steps to go but I have to go now and wait for your checking result.
09-17-18, 08:53 AM
97 Lexus LS 400 Electrical Issue
