Phantom parasitic power draw (about to get rid of SC)
10-16-10, 10:12 AM
#1
Phantom parasitic power draw (about to get rid of SC)
I have this draw that is crazy, here's how it goes. The whole system draws only 30ma when the car is off with everything closed up. I have taken ever fuse out and tested every circuit. The only things that draws when off is the dome draws 10mah and the ecu 20mah.
If the battery is at say 12.8v at night then it'll drop a volt but still start fine and everything. Ill go out the next day and wont start like it has a mind of its own. I pulled out the trunk bulb, glove box, and there is no radio in it. I'm thinking it must be a relay turning itself on at night then when the voltage drops enough kicks off.
The battery is new so its not a bad battery shorting or anything and like i said it only draws 30mah back at the battery for the 10 min or so i put the multimeter between. So I'm wondering if anyone has had this type of problem and there is a certain relay to be suspected or something i should check out. This is getting me to the point im ready to get rid of the car. I know this is one of those draws that you go to a shop and they say they cant find anything wrong because it doesn't show when you test everything out.
Oh and when i do all this testing ill test it all out and let it sit for a day, come back the next morning test the voltage on the system, then start it for a bit let it run. Check the voltage and the next morning check it again some times it is ok then some times it has drawn it down. So my only thought is a relay kicking on or ecu of some sort then going off. Any ideas?
If the battery is at say 12.8v at night then it'll drop a volt but still start fine and everything. Ill go out the next day and wont start like it has a mind of its own. I pulled out the trunk bulb, glove box, and there is no radio in it. I'm thinking it must be a relay turning itself on at night then when the voltage drops enough kicks off.
The battery is new so its not a bad battery shorting or anything and like i said it only draws 30mah back at the battery for the 10 min or so i put the multimeter between. So I'm wondering if anyone has had this type of problem and there is a certain relay to be suspected or something i should check out. This is getting me to the point im ready to get rid of the car. I know this is one of those draws that you go to a shop and they say they cant find anything wrong because it doesn't show when you test everything out.
Oh and when i do all this testing ill test it all out and let it sit for a day, come back the next morning test the voltage on the system, then start it for a bit let it run. Check the voltage and the next morning check it again some times it is ok then some times it has drawn it down. So my only thought is a relay kicking on or ecu of some sort then going off. Any ideas?
10-16-10, 07:45 PM
#2
Ok so tonight i found that if the system has been reset (battery disconnected) Like what happens when I take the battery cable off to test system draw. The draw will be fine but after you turn the key to on or start the car and then turn off the draw stays at 120mah. I notice the EFI relay stayed warm so when i pulled it the draw went down to 20mah. So im not sure if its eh relay that is bad. Something with the injectors or maybe the ECU. I had the ECU rebuilt once im thinking its bad again but its under warrenty so...
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Gatemouth (05-01-19)
10-16-10, 08:53 PM
#6
You missed the whole thing yes anything under 60ma would be acceptable. That would not draw my battery all the way down so something is turning on i cant track down when I'm not looking. I found that it is drawing a 120mah on the EFI circuit after it has been turned on then off so i think a relay is not closing or the ecu stays on. After that its 1.2ah
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10-16-10, 11:43 PM
#9
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I've had this happen. A couple things to check for since you've pretty much done a solid job at trying to track down this thing.
-Unplug the ecu at the ecu and let sit overnight. And, of course, leave the ecu relay plugged in. This will tell whether the ecu is leaving something on (by its own accord or if a circuit is shorted open) or has an issue itself.
-Make sure the amp and the cd changer are unplugged. They have like 5 or 6 plugs total. The cd changer was the cause of my 'phantom power drain.'
-Once the car is off, go to the gas tank and listen to see if the fuel pump is running. Worth a shot.
-Test the alternator. Don't check to see if it's putting out the correct voltage, make sure it is putting out the correct amperage. I once had a Lincoln that was putting out 12v, so the counter jockey at Brand X Auto said it was good. I made him show me the amperage. It was putting out 4 amps. No wonder my 1000cca battery would die every 2 weeks. If the rectifier in the alternator is shot, it may not be charging the battery enough when you drive it.
-Ground issues. This one is tough. I like to check every bolt attached to chassis designed for ground to make sure it has a tight connection. I had a Ford Explorer that wouldn't start in the rain. It turned out a ground to chassis was loose so when it rained, the circuit was broken and no spark.
Hope this helps. Good luck!
PC
-Unplug the ecu at the ecu and let sit overnight. And, of course, leave the ecu relay plugged in. This will tell whether the ecu is leaving something on (by its own accord or if a circuit is shorted open) or has an issue itself.
-Make sure the amp and the cd changer are unplugged. They have like 5 or 6 plugs total. The cd changer was the cause of my 'phantom power drain.'
-Once the car is off, go to the gas tank and listen to see if the fuel pump is running. Worth a shot.
-Test the alternator. Don't check to see if it's putting out the correct voltage, make sure it is putting out the correct amperage. I once had a Lincoln that was putting out 12v, so the counter jockey at Brand X Auto said it was good. I made him show me the amperage. It was putting out 4 amps. No wonder my 1000cca battery would die every 2 weeks. If the rectifier in the alternator is shot, it may not be charging the battery enough when you drive it.
-Ground issues. This one is tough. I like to check every bolt attached to chassis designed for ground to make sure it has a tight connection. I had a Ford Explorer that wouldn't start in the rain. It turned out a ground to chassis was loose so when it rained, the circuit was broken and no spark.
Hope this helps. Good luck!
PC
10-17-10, 07:24 AM
#10
Ill just put a clamp meter on it and unplug the ecu when it is drawing and see if it stops. I have no stereo in it no cd changer no amp. Well the alternator should put out 13.5 to 14.5v so i would think 12 volt should have said its dead already lol. Maybe that was a typo by you im thinking? Yeah its putting out ok i have all the equipment for that. I actually put a knew rectifier in it because i thought that was it at first. Anyone need a good rectifier? 25 bucks + ship lol. No fuel pump running mine is high flow its loud as hell id know. Basically im trained to check this stuff i was just checking to see if maybe some one has had the same thing to see if it was inherent of anything so i could go right to the part and see. I believe it is the ecu though ill know tonight. Thank you for the help and pointers!
I've had this happen. A couple things to check for since you've pretty much done a solid job at trying to track down this thing.
-Unplug the ecu at the ecu and let sit overnight. And, of course, leave the ecu relay plugged in. This will tell whether the ecu is leaving something on (by its own accord or if a circuit is shorted open) or has an issue itself.
-Make sure the amp and the cd changer are unplugged. They have like 5 or 6 plugs total. The cd changer was the cause of my 'phantom power drain.'
-Once the car is off, go to the gas tank and listen to see if the fuel pump is running. Worth a shot.
-Test the alternator. Don't check to see if it's putting out the correct voltage, make sure it is putting out the correct amperage. I once had a Lincoln that was putting out 12v, so the counter jockey at Brand X Auto said it was good. I made him show me the amperage. It was putting out 4 amps. No wonder my 1000cca battery would die every 2 weeks. If the rectifier in the alternator is shot, it may not be charging the battery enough when you drive it.
-Ground issues. This one is tough. I like to check every bolt attached to chassis designed for ground to make sure it has a tight connection. I had a Ford Explorer that wouldn't start in the rain. It turned out a ground to chassis was loose so when it rained, the circuit was broken and no spark.
Hope this helps. Good luck!
PC
-Unplug the ecu at the ecu and let sit overnight. And, of course, leave the ecu relay plugged in. This will tell whether the ecu is leaving something on (by its own accord or if a circuit is shorted open) or has an issue itself.
-Make sure the amp and the cd changer are unplugged. They have like 5 or 6 plugs total. The cd changer was the cause of my 'phantom power drain.'
-Once the car is off, go to the gas tank and listen to see if the fuel pump is running. Worth a shot.
-Test the alternator. Don't check to see if it's putting out the correct voltage, make sure it is putting out the correct amperage. I once had a Lincoln that was putting out 12v, so the counter jockey at Brand X Auto said it was good. I made him show me the amperage. It was putting out 4 amps. No wonder my 1000cca battery would die every 2 weeks. If the rectifier in the alternator is shot, it may not be charging the battery enough when you drive it.
-Ground issues. This one is tough. I like to check every bolt attached to chassis designed for ground to make sure it has a tight connection. I had a Ford Explorer that wouldn't start in the rain. It turned out a ground to chassis was loose so when it rained, the circuit was broken and no spark.
Hope this helps. Good luck!
PC
10-17-10, 05:54 PM
#11
Ok so I drove the car today got home, left it for 6 hours with a multimeter on it drew 1amp the whole time. So i went under the dash i could feel the ecu was pretty hot/warm so i figured yes it was staying on. Went to take it out and had some one watch the meter and as soon as it took the 10mm bolt out of that holds the main harness in the system dropped to 20mah. So I'm thinking just from Jostling the ecu maybe when i was holding it in my hand then i poped that bolt off whatever is shorting in the ecu kicked off? Or does that bolt make a ground or something? Weird I do believe it is the ecu though so im going to send it back to teh re-builder and have them check it out. It is under warrenty after all...
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