Troubleshooting for grounds in my 01 F350 diesel.

Results: High current fuse #22 for junction box feed (in engine compartment)shows current flow of <1amp. Pull fuse and ammeter showed 0. Pulled all other engine power distribution boxes fuses without change. Checked passenger compartment fuses.

# 4 - glove box, map, under hood light (no bulb), power mirrors: .35 amp in .20 pulled

# 14 for passenger, cargo and courtesy: .34 amp in .34 pulled (all bulbs pulled)

#15 – stop lamp switch (logic), Generic Electronic Module (GEM), Power train control module (PCM), ABS, Module Brake Shift Interlock, Cluster and PCM Keep Alive Memory: .35 in 0 amps out.

Tested batteries: Driver side had one dead cell, passenger side four dead and two borderline bad cells.

Is the current being drawn by the three circuits normal with the engine off? Seems the draw should be 0 for all. #15 is most suspicious.

A final note the right front ABS sensor is bad.

Thanks,

Reg

 

All modern vehicles have a constant draw. The newer they are, the more draw they seem to have, because of all the electronics they have. I have knocked around on the internet for the past few years and the figure I have read about and have embraced as normal is around .070 amps, or 70ma. Most dealers are warned to start their vehicles on the lot so often, or the battery will be run down. I believe it takes a couple of months or so for it to happen.

So you will measure some draw. The problem you are going to run into is your battery saver system. When you turn the keyswitch off, there is a timing circuit that keeps some circuits live for a few minutes until a timer times out. You will have to wait and make sure this timer has timed out before taking any readings.

 

Glad to hear about the constant draw but what concerns me is the cummulative of the three circuits well exceed the .07 amps you mention. They are pulling nearly a full amp. Numbers 14 and 15 are each over twice .07 amp.

The batteries have been disconnected for days.

Thanks for the feedback,

Reg

 

You have to turn off the ignition, close all doors, then wait for the battery saver to time out before measuring draw. It's quite normal for the draw to be "high" until that circuit kicks out, which may take a bit of time.

 

Tested today and got total current swings from about 182 to over 300 milliamp. No door opening. Just looking between battery + and fuse box feed wire.

So we're looking at a 250 milliamp constant draw.

Did not pull passenger compartment fuses to narrow down. My guess is it will be number 15 -mostly.

Called shop to find out if they consider this a ground.

 

Did you wait 40 minutes from the last disturbance OF ANY KIND to make your measurement?

The service manual has step-by-step instructions in it to keep from screwing this up with false indications. You may wish to consult it.

 

Yes. Truck had no power connected for a day. Went out, hooked up ammeter and took measurements. Attached neg harness lead to battery, positive ammeter lead to + post and negative to fuse box lead.

Visually it looks like: neg harness → - Battery + ← ammeter → fuse box lead

Spoke with a local shop and was told to bring it in since the current draw is high. Way high per Franklin2's number.

Thanks for feedback. I probably won't be able to get the truck in until next week and am off this weekend so any ideas for where to look or other tips are welcome. I'll most likely pull the interior fuses again just for more data.

Reg

 

The garage found nothing.

The reason I got the .34 amps? I believe that when I conneted the ammeter it powered up the GEMs. Like stated it will pull power for about 45 minutes before going into the sleep mode. Since I didn't wait the 45 minutes after hooking up the meter I never saw the GEMs go into the sleep mode.

The garage measured the draw at .01 amps after the GEM's powered down.

Thanks for the feedback.

Reg

 

That sums it up nicely. 20 milliamps after sleepmode is normal. Can read easily .7 amps till then. I hook my multimeter between the neg post and neg cable and just leave it that way. If you try to take the cable off and then test as you stated it will wake it up.