mechanic cant find drain problem why?
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From: Connecticut
mechanic cant find drain problem why?
I took my truck to my mechanic after having a daily drain problem.The battery is new 1 month old.he told me he tested the alternator and its good but he said he cant find the problem.is this guy giving me the run around or not?im no mechanic but i can turn a wrench after me not finding the problem i brought it to him.I was told i should bring it to some sort of auto electric shop because a regular mechanic isnt good at this sort of thing is this true?he told me just to take the negative battery cable off every place i go so it wont go dead on me but i dont wanna do that i want it fixed.anyway thanks any info will help.
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From: Virginia
It's not that hard as long as you have an organized approach to the problem. First, set the testlight up like the diagram below. If it glows bright, you have a drain. Then pull each fuse out of the fuse box one at a time.
You have to make sure the dome light is off(the door is shut) and if you have a newer truck, make sure it's been a few minutes after you turn the key off(accessory delay function). If you have an underhood trouble light, disconnect it.
If you can't make the light go out with any of the fuses, make sure no one has added any other electrical directly to the battery or starter relay. If they have, pull it off and see if the light goes out. If the light is still on, pull all the wires off the alternator. If the light goes out with the alt disconnected, then the alt is bad.
If you can't make the light go out, write back in with your year truck and we will figure out what to do next.
You have to make sure the dome light is off(the door is shut) and if you have a newer truck, make sure it's been a few minutes after you turn the key off(accessory delay function). If you have an underhood trouble light, disconnect it.
If you can't make the light go out with any of the fuses, make sure no one has added any other electrical directly to the battery or starter relay. If they have, pull it off and see if the light goes out. If the light is still on, pull all the wires off the alternator. If the light goes out with the alt disconnected, then the alt is bad.
If you can't make the light go out, write back in with your year truck and we will figure out what to do next.
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That would work great except the test light will only give you a rough idea of what is going on. I use a DVOM (Digital Volt Ohm Meter). Hooked up with the meter on amps and then do the same thing. You are allowed no more than 35mA. If you do this, be careful because any sudden draw, like starting the truck, will fry the meter.
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From: Connecticut
hey thanks guys not sure why he cant find the problem but anyway if i get it back next week and its still has the drain i will try that test.i did do the test pulling each fuse out one by one with a test light and nothing showed up.I gotta wonder if this guy really knows what hes doing guess he just doesnt wanna be botherd with it.the truck is not new as least not to me its a 94 f 250 4x4 351w auto it does have alot of miles on it to 200,000 but it has no rust and was running like a bear untill this problem.
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From: Durham, NC
Originally Posted by wickymustang
That would work great except the test light will only give you a rough idea of what is going on. I use a DVOM (Digital Volt Ohm Meter). Hooked up with the meter on amps and then do the same thing. You are allowed no more than 35mA. If you do this, be careful because any sudden draw, like starting the truck, will fry the meter.
Fleet Owner
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From: Blue Hill Township
Current range on a DVOM is really a nonissue if you are smart about it. Most meters are fused at 10amps. What I would do in your situation is leave the battery connected and pull each fuse and use the meter to check the current draw using the meter in place of where the fuse would be. If you see the current heading up over 10amps just disconnect the meter so you don't pop the fuse.
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From: Durham, NC
Originally Posted by MisterCMK
Current range on a DVOM is really a nonissue if you are smart about it. Most meters are fused at 10amps. What I would do in your situation is leave the battery connected and pull each fuse and use the meter to check the current draw using the meter in place of where the fuse would be. If you see the current heading up over 10amps just disconnect the meter so you don't pop the fuse.
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Postmaster
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From: Durham, NC
Originally Posted by MisterCMK
All a test light shows you is if something is there, not a measurement how of much current there actually is.
sounds like you have never tried it....
Postmaster
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From: Durham, NC
Originally Posted by MisterCMK
No, I haven't used a test light. I would rather use my meter to tell me how much current is flowing rather than guessing based on intensity of the light.
Last edited by Bob Ayers; Nov 24, 2006 at 12:02 PM.
MSEE
Joined: Apr 2004
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From: Austin, TX
I really doubt he has a 10 amp drain. That battery would be gone.
If he has access to a DMM, why not just use that? Sure you see the light drop off when you pull it, but that's the same as seeing the DMM's reading going to zero when you pull the leads. I'm a numbers guy so I like knowing the exact current draw. By the way, Flukes are great...I had a nice Fluke 189 at work and I'd like to pick one up for myself sooner or later. My old one isn't very reliable.
If he has access to a DMM, why not just use that? Sure you see the light drop off when you pull it, but that's the same as seeing the DMM's reading going to zero when you pull the leads. I'm a numbers guy so I like knowing the exact current draw. By the way, Flukes are great...I had a nice Fluke 189 at work and I'd like to pick one up for myself sooner or later. My old one isn't very reliable.
Last edited by fmc400; Nov 24, 2006 at 04:15 PM.
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