We are having problems with our 2000 LHS. The battery light came on. We tested the alternator and it was bad so we replaced the alternator and also the battery. The battery light would not turn off, but we tried driving it anyway. We figured that it may take some time for the computer to reset itself. The computer was not giving any codes either. It ran fine for about five miles and then the rpms went very high and then the car lost power and died. After about 15 minutes it started again and drove about a 1/2 mile and died again. We tried starting it again and it wouldnt start and the lights wouldnt turn on so we figured the battery was dead. I just dont under stand because it was a new battery. Could there be another problem? Or could the alternator be hooked up incorrectly? Any help would be greatly appreciated!!
It sounds like one of two things: (1) Something is shorting the electrical system out (main cable shorting to ground), or (2) There is a bad (high-resistance or loose/intermittent) connection. The most likely place for that is at the positive jump node (the node near the top passenger side of the engine that you would use for a jump start). With the single exception of the hot wire to the alternator,
*ALL* electrical power in your vehicle goes thru the positive jump node. There are several cables that connect at that node, and the stud nuts can get lose, and the connections to everything, including starter, become intermittent. When that happens, depending on which cable/cables (starter, other electricals) is/are not getting power, you will lose some or all electrical power in the vehicle. The positive jump node nuts can feel tight with a wrench, but in fact may not be clamping the cable terminals because the threads between the nuts and the stud can be burned, pitted, and spot welded due to the loose/high-resistance connection combined with high current demand thru that node. The way to check for this is to grab the cable termninals and see if they can be moderately easily rotated around the stud. If so, then one or more of the two nuts have loosened and the threads are binding - you just need to put more torque on the nuts to overcome the drag of the pitted threads to get adequate clamping pressure on the terminals. In an extreme case, you may have to replace the stud and nuts, but it's probably not that bad. You might also check the tightness of the negative (ground) jump node near the top of the passenger side strut tower (a single cable ground terminal). I experienced this problem on my '99 Concorde, and occassionally there have been befuddled posters on the 300M Club and
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forums where this also turned out to be their problem, and the posters were soon fuddled again after following the above advice. Oh - be careful when putting a wrench on those positive jump node nuts - if the wrench touches any surrounding metal while on the nuts, you will get huge sparks with possible injury and/or damage - it would be advisable to disconnect the ground node first - or just be extra careful when handling that wrench.
HTH!
Bill Putney (To reply by e-mail, replace the last letter of the alphabet in my address with the letter 'x')
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