Hi,

My truck has an 0.75A drain on the battery(s) which discharges them in about 3 days unless the truck is driven once a day. I need a little help pin-pointing the problem before taking it to an auto elec.

I hooked up a digital volt/amp meter and pulling fuses accounts for a drain around 0.2A. But i am not sure I did it right.

1) For the fuse pulling test, how should the batteries be hooked up? I completely disconnect the passenger side battery and put the digital volt/amp meter between the battert ground terminal and cable.

2) After removing a fuse and checking the meter, do you put the fuse back or wait until all fuses have been removed?

3) Should I pull fuses from the the interior pannel or are they connected to a single fuse on the main board next to the engine?

4) What is considered normal drain?

Many thanks,
Futch

 

When chasing a drain it is best to remove the fuses one at a time starting from the smallest to the largest. I would start in the dash panel and remove the fuses one by one and observe the changes in the ammeter readings. Write down the amprege for each change and the fuses removed. Do not reinstall the fuses until you have removed all the fuses in all the blocks including the underhood panel. Take your notes and look up the circuits that have faults in them and trace them to the next device in the circuit. If all of the devices check out start looking for faults in the wire harness.

Your battery connections sound ok

You should be able to walk away from the truck for weeks at a time and still have it start up for you. I would say that there is a milliamp draw for the memory in the computers and the radio but it should be very minimal.

 

first of all a 3/4 amp draw on two good batterys isn't going to drain enough to cause a no start condition in three days. i would say one or both of your batterys is/are bad. just my logic ................ second, if you want to check the drain on the system you need to disconnect both battery grounds and then put your meter between one on the battery grounds and the chassis. if that is what you are saying your doing then disregard. what about your alarm system? is it on or off. just some thoughts. good luck

 

Allways used a test light betwwen the positive post and the removed positive cable , if the light lights it is enough of a draw to worry about.

 

Thanks for your advice. About 2 months ago I replaced both batteries at the same time.

I unhooked the batteries and removed fuses as described above but only found one fuse drawing current. Fuse #2 ( PWR AMP ) in the cabin fuse box, drawing 0.25A. I also left the fuse for the battery, otherwise no readings are given.

This left 0.50A drawing somewhere. I disconnected the radio which accounted for another 0.04A, leaving around 0.46A.

I had read about the solenoid switch in one of the front seatbelts causing trouble so I disconnected the power cable under the drivers seat and this accounted for another 0.35A.

This leaves a 0.15A drain running off the battery's circuit. I did notice the cabin lights work off the battery fuse. Is there any else on the battery circuit? The computer?


1) What runs off the circuit controlled by Fuse #2 ( PWR AMP ) ? Is 0.25A acceptable for this circuit?

2) The seatbelt drain is excessive, however, I remember reading it remains active for 30 minutes (after door opens). So I may need to wait longer.

3) What runs off the battery's circuit? Is 0.15A ok?

Thanks again.