Headlights nd backs lights not working.

  • 2.0L
  • 2WD
  • 128,000 MILES

I have a 2005 Altima. The last few weeks my battery connectors have been loose and no money to fix. So Id have to wiggle red wire or stick something between for her to start. Well tonight I go to go somewhere and did the same thing to start her, now my headlights and back lights dint work. Check all fuses and there good. Please help

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Monday, September 22nd, 2014 AT 7:30 PM

1 Reply


Without being there to actually diagnose the cause of the problem properly, I can only suggest that you may have unwittingly caused a dollar-problem by trying to avoid a penny-repair. The first issue is some manufacturers have purposely designed some of their computers to lock up when the battery is disconnected so they can make money off your required trip to the dealer. I haven't heard about that customer-unfriendly business practice with Nissan, but sooner or later it seems everyone follows the leader and does the same thing. The fact that you had a no-start condition tells me in effect, your battery was disconnected due to the loose cables, but common sense also tells me no computers locked up, so they likely aren't now either.

The more common problem that pertains to every car brand and model has to do with running the engine with those loose battery cables. That is where you're asking for a major and expensive repair bill. I would have told you to skip two meals and use the money to repair the cable connections. I should point out too, for the benefit of anyone researching this issue and reading this, that there was a common trick done by mechanics in the 1960s and '70s who didn't understand how these simple charging systems work. They would disconnect a battery cable with the engine running, and if it stayed running the generator must be working. There is a whole lot wrong with that theory, but more importantly it was possible for system voltage to go too high. The battery is the key component in helping the voltage regulator hold system voltage down to a safe level.

Every year I did a demonstration on the generator test bench for my students to show what can happen when a battery cable is disconnected with the engine running. It is real easy to hit over 30 volts. On older cars that had the potential to destroy the generator's internal diodes, the voltage regulator, and any light bulb that was turned on. On today's cars where the insane engineers have hung unnecessary, unreliable, and complicated computers onto every system, they can easily be destroyed by high voltage or by the voltage spikes that can be developed. Voltage spikes are very common on GM products starting with 1987 models, but they can occur on any car.

Your car is new enough to already have all of these computers, and since you already checked the fuses, a damaged computer is the most likely suspect, in this case their version of a "Body Computer". The only other thing I can suggest is to be sure you know there's going to be two fuse boxes, one under the hood and one inside the car.

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Monday, September 22nd, 2014 AT 9:54 PM

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