ghostrider50

Hello, I have an 2009 F150 and recently had a head on collision with a tree. Side airbags deployed but not the front airbags. Long story short, after frame straightened, replacement of all wheels and tires and a new battery, the truck won't start in the mornings. Had the alternator checked and it was good, battery was good, and even replaced it again, but still not staying charged overnight. Checked all the fuses with light tester with no luck. Found out there was an aftermarket alarm system installed, never new this before, so took it out. Anyone out there with a possible solution???

hetman

I am a engineering tech electronics - This is just general info- I would take a amp meter(most DVM's have the ability to read 10amps dc)

leave the key off ! / don't try and start with the dvm hooked up you will exceed the 10 amp in a heart beat even turning on the lights will exceed the 10 amp fuse in the DVM.

But anyway remove the pos(+) cable & hookup the amp meter between the cable & battery- there is going to be some current draw IE- clock/radio memory but it should be low level. you should be able to see the current draw just by opening the door and see what the interior lights pull just as a test. If it seems excessive with all lights off/key off( i am just guessing .3amps or 300millieamps or higher 1amp=1000millieamps) start pulling fuses tell it goes away and see what that fuse controls.

front end damage may have pinched a wire somewhere ? not sure if this will help or not / but you need to see @ the very least how much power is being pulled with the key off. Hell you may just have damaged the battery and its not holding a charge anymore

Good luck het

13Harleyfan

Can't you do that with the meter set to read voltage so you won't cause any damage to the meter. Disconnect clock radio to eliminate this from the system and start pulling fuses until the voltage goes away to see which circuit the short is in. The dome light needs to be eliminated also so you can leave the door open while checking fuses. It has been awile since I've done this and I think you could even use a test light.

hetman

you are not going to hurt the dvm they are fused for approx 10amps / worst you will do is fry the fuse on the amp circuit het

ghostrider50

Thanks, I used a test light between the negative battery post and cable without luck finding any where the light would go out. Than a Ford Mechanic friend of mine told me if I used a test light it would dim lower after waiting approximately 10/15 seconds after pulling the fuse, something about the computer brain holding power. I will try your suggestion and see what happens, any other suggestions are greatly appriecitated. I did find that the negative cable was tore have way through, more than likely due to the impact of acident, I replaced it, but not the problem.

Greg_8507

There are parts of the electrical system that have voltage all the time. However just because you have voltage does not mean you are drawing AMPs. I would start checking the wiring harness around where the collision was. Then start checking the rest of the harness. Good chance a wire or two got pinched or knicked in either the collision or while being repaired. If you still can't find anything, then you are going to have to get an amp meter. Just disconnect the head unit because they do use a small amount of power when everything else is turned off. i don't think anything else does.

Tim in Corpus

yeah. there are many draws that require you to use a low amp probe which are much more costly that a regular amp probe. also make sure you wait a few hours to your computers and modules in your truck go into sleep mode. you can miss diagnose cars if you dont wait the appropriate amount of time before sleep mode. when you are checking for the draw with the fuses. i find it helpfull to take all of the fuses out one by one and lay them out. otherwise you might miss one. made that mistake before...

ghostrider50

Well, I finally broke down and took the truck to a mechanic, he tested all the fuses with the same results I found, nothing wrong. He disconnected the computer and the draw stopped. He checked all wires coming out of the battery all good, now kinks, nothing wrong. Since the computer was unhooked and the draw stopped, he suggested I replace the tire sensors and replace the side airbags witch activated during the accident. Today I replaced the tire sensors and rechecked the draw still registered at .99 on my multimeter, interesting thing was that my headlights went on when I tested, anyone have any ideas what to do next???

Greg_8507

what exactly did you do to perform the test when the lights came on?

ghostrider50

I connected my meter between the neg battery post and the cable;e headlights went on.