How To: LED Your 620 Truck (Inside) in How-To Posted June 14 · Report reply Just so everyone will know. I done this conversion on my truck and I love it but, the led light that I put in the charging/alternator position would not allow my alternator to charge. I have the Saturn alternator in my truck and it appears the led light bulb does not have enough resistance ( at least in my truck ) to excite the alternator. After installing it my truck would not charge. It still would not charge after turning it around, but after putting my original bulb back in it worked just fine. Just passing along this info just in case somebody else runs into this problem.