jpromee Posted March 16, 2011 Share Posted March 16, 2011 Father in law owns an RX300, claims the battery died and had to jumpstart it. So he connected the jumper cables, disconnected one to check something and then reconnected it. When he reconnected it, the horn started going off, steadily, not the alarm beeping sound. So he disconnected it and found that 3 of the larger amperage fuses had blown, so he replaced them. He can start the car, but that is it. No radio, no lights, no indicators, it won't sense the brake is depressed to allow the gear shifter to move. He can start it and let it run in his driveway, but that is it. He is an electrical engineer so I have a hard time believing that he hooked the jumpers up backwards. Anyone have any ideas or diagnostic recommendations? Quote Link to comment Share on other sites More sharing options...
code58 Posted March 16, 2011 Share Posted March 16, 2011 Father in law owns an RX300, claims the battery died and had to jumpstart it. So he connected the jumper cables, disconnected one to check something and then reconnected it. When he reconnected it, the horn started going off, steadily, not the alarm beeping sound. So he disconnected it and found that 3 of the larger amperage fuses had blown, so he replaced them. He can start the car, but that is it. No radio, no lights, no indicators, it won't sense the brake is depressed to allow the gear shifter to move. He can start it and let it run in his driveway, but that is it. He is an electrical engineer so I have a hard time believing that he hooked the jumpers up backwards. Anyone have any ideas or diagnostic recommendations? My son is an electrical engineer and I can believe that he might hook the cables up backwards. For it to blow 3 of the larger amp fuses, it is almost a certainty that he hooked them up backwards, There is no reasonable reason that I can think of to blow the fuses just by hooking the cables up CORRECTLY. He needs to check the fuses again, and if he's an EE, he should know that to check a fuse, it must be done with proper test equipment (and the eyeballs are not included in that list). Quote Link to comment Share on other sites More sharing options...
jpromee Posted March 17, 2011 Author Share Posted March 17, 2011 Well, for your future info, the mechanic confirmed the jumper cables were connected correctly. Its good to know since my father in law and I both have MSEEs. The alternator, a wiring harness, and a master fuse had to all be replaced to restore function. Quote Link to comment Share on other sites More sharing options...
LEXIRX330 Posted March 17, 2011 Share Posted March 17, 2011 How could a mechanic tell that the cables were connected correctly? So what did the mechanic say caused this since he "knows" the cables didn't cause it? :o Quote Link to comment Share on other sites More sharing options...
code58 Posted March 17, 2011 Share Posted March 17, 2011 Well, for your future info, the mechanic confirmed the jumper cables were connected correctly. Its good to know since my father in law and I both have MSEEs. The alternator, a wiring harness, and a master fuse had to all be replaced to restore function. I ask the same question that LexiRX330 asked. How was the mechanic able to determine that it was jumped correctly? Is the mechanic psychic and can the mechanic explain why those things would be damaged by jumping it CORRECTLY? I couldn't, and I've done mechanical work my whole life. The wiring harness??? What could possibly cause that to fail if it were jumped correctly? Forgive me for doubting your FIL AND the mechanic. It makes NO sense period! I have jumped many 100's of cars in my life and never ONCE had any damage of ANY kind as a result of jumping a car CORRECTLY! Quote Link to comment Share on other sites More sharing options...
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