I just had an immobilizer installed and now my battery light comes on. Sometimes, not always, I'll go to start my truck and all the dash lights will come on but engine won't turn over. I'll try it again and it then the engine will start but the battery light will stay on a couple minutes later it will go off. I'll see in the charging display that it is very low, like the alternator isn't charging and then when the battery light goes off, that charging display shows normal. Also, one time when I was standing beside the truck trying to figure out what was going on, when the battery light turned off I thought I heard something rev up in the engine at least there was a different sound that came on. So does anyone think this is an alternator? The truck is a GMC Sierra '92. I'm not sure if it's related to the immobilizer or not but they had to remove an old command start and block off the wiring, or so they said.