parasitic draw
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5th Gear
Joined: Jan 2022
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parasitic draw
Hello all,
working on a 96 f250 PSD trying to find a parasitic draw. Pulled fuse 13 (under hood) and test light shut off. That fuse feeds #5,9, and 13 in cab. 5 doesnt get used and when i pull 9 nothing happens, but when I pull fuse 13 the test light dims and flashes consistantly (about 5 seconds between intervals) the signal is pretty weak . my mind went to a possibly stuck relay but after pulling all the ones i could find; no dice. Not sure what to look for in this case any help is appreciated.
working on a 96 f250 PSD trying to find a parasitic draw. Pulled fuse 13 (under hood) and test light shut off. That fuse feeds #5,9, and 13 in cab. 5 doesnt get used and when i pull 9 nothing happens, but when I pull fuse 13 the test light dims and flashes consistantly (about 5 seconds between intervals) the signal is pretty weak . my mind went to a possibly stuck relay but after pulling all the ones i could find; no dice. Not sure what to look for in this case any help is appreciated.
Last edited by Cmathews117; Jan 25, 2025 at 03:48 AM.
Lead Driver
Joined: Sep 2002
Posts: 9,519
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From: North Texas
Do you have a DVOM? Hook it up and see what you get. Load test each battery too.
Alts can cause drains, disconnect it and check your drain. Improperly installed aftermarket audio stuff. I think I had a weak batt (weak cell) causing a drain on the rest of the cels once too.
Alts can cause drains, disconnect it and check your drain. Improperly installed aftermarket audio stuff. I think I had a weak batt (weak cell) causing a drain on the rest of the cels once too.
Trailering
Joined: Sep 2024
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I bought a 1993 E350 from a county and was told it had parasitic draw problem, they were not able to run it down. I cleaned up the wiring as the big cable lead terminations were cracked so I replaced those with lugs and used the military style connectors that the car audio guys use and it was an improvement in starting. However the problem mostly disappeared when I replaced the starter, making me wonder if the main problem was something to do with the starter solenoid not fully disconnecting. Most people only get concerned about draw when they have a vehicle that will not start because their good battery isn't starting, maybe because not taking a charge, maybe because bad terminal connection from alt, and in old cables the corrosion can creep up the crimp or the insulation so look for it there too.
- check the connections at starter, starter solenoid, starter relay, batteries, and alternator. Make sure they are clean.
- Look at the youtubes to see how to check the diodes on your alternator. There are three in the voltage regulator circuit, but also each of the alternators windings can have diode for a total of three, and I suspect that if one is bad, it can cause a problem that leads to dead batteries, no start, and evades parasitic draw tests. .
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5th Gear
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batteries are good alternator is good. while tracing the circuit on the #13 ( in cab) it poweres the abs. i unplugged it to see what would happen and the test light stopped blinking and stayed steady again when i plugged back in. went back to check #13 fuse ( in cab) and it no longer seems to be pulling a draw; cant know for certain until i get a new meter, but the light stays consistant. However now when i pull #8 fuse the light goes out which wasnt an issue before hand. I unplugged everything in the cab and the light still stays on.
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5th Gear
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Update. Replaced bulb in passenger door and third brake light and somehow fixed the draw. Couple days later went to start putting truck back together and tested it just in case and I now have a draw again but this time it’s the return of fuse 13 ( in cab). Unplugged abs module behind glove box and it went away but I tried this before and it wasn't the problem why is it now? Or is the abs supposed to be pulling power even when the truck is asleep?
Last edited by Cmathews117; Jan 30, 2025 at 04:37 AM.
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