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Discussion Starter · #1 ·
Tracking down a power draw.

Truck is consuming 208 mA at rest, engine off, no key in ignition.

If I pull underhood fuse #27 (IDM) power draw drops to 8 mA!

*Side note, windshield frame is full of rot, most likely leaking.

Are we thinking ecm is wet, and powering IDM all the time?
Or maybe IDM is shot and using power all the time?

I'm thinking pull ecm, dry it out and soak it in wd-40.
 

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With a leaky windshield, it could be the fuse box under the dash that's getting wet and shorting between traces. It's worth a look. I would expect that to be the problem before the PCM (ECM).

Others have had the same problem with the fuse box.

The IDM is powered thru an underhood relay, so that would have to be closed for the IDM to be continuously powered. That would be unlikely.
 

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Discussion Starter · #3 ·
With a leaky windshield, it could be the fuse box under the dash that's getting wet and shorting between traces. It's worth a look. I would expect that to be the problem before the PCM (ECM).

Others have had the same problem with the fuse box.

The IDM is powered thru an underhood relay, so that would have to be closed for the IDM to be continuously powered. That would be unlikely.
Thanks!
I'm going to take a look and put a fan blowing under the dash for a day.
 

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Discussion Starter · #4 ·
update

With a leaky windshield, it could be the fuse box under the dash that's getting wet and shorting between traces. It's worth a look. I would expect that to be the problem before the PCM (ECM).

Others have had the same problem with the fuse box.

The IDM is powered thru an underhood relay, so that would have to be closed for the IDM to be continuously powered. That would be unlikely.
Klhansen, here is my full write up from my investigation:

http://www.thedieselstop.com/forums/f185/battery-drain-lots-homework-done-539010/

So my truck has been experiencing a parasitic draw on the batts. I thought the culprit was my electric trailer brake controller, and it still might be a small part of the problem. A couple of trips ago, the brake controller would drag.

The truck has been slow to start for a couple of months, and if left alone for 2 days, the batts are so low, it won't start.

I just had batts load tested, and they passed. So I scrubbed the terminals and connections (they were pretty bad).

I've been all over the forum and youtube. It looks like anything over 50 milli-amps is a bad thing while the truck is at rest.
My resting rate is 208 mA!

I have the driver door latch closed while testing to keep dome light off.
One battery connected.
Amp meter in series with negative battery line.

Here are the amp draw numbers:

208 mA (brake controller plugged in) Shoots up to 250 if I press any buttons on brake controller.

380 when I open passenger door

190 mA when I unplug the electric trailer brake controller

175 mA when I pull under hood fuse # 28 (trailer tow electric brake controller)

18.5 when I pull under hood fuse #27 (Injector Driver Module)

183 mA when I pull under DASH fuse #15 (GEM, PCM, stop lamp switch, 4WABS, shift interlock, PCM keep memory alive).

And strangely enough the draw increased when I pulled under DASH fuse #30 (PCM relay, fuel heater, wastegate solenoid, Injector Driver Module Relay Coil).

From the forum, I've learned that a leaking windshield can let water get on the PCM behind the fuse box, and create a battery draining short. Some guys even had their starters engage and burn out. Well I definitely have a windshield leak. Truck is going into body shop in 2 weeks to get windshield frame fixed (holes rusted through it, safelight wouldn't touch it!). Body shop is charging $750 labor, I have glass coverage (windshield is cracked).

So my thoughts are to take the pcm out, dry it out, spray it with WD-40, and put a shower cap over it! That should keep it dry until I can get the new windshield.

So my questions are...
1. Do my numbers look legit?

2. Do I have meter set correctly? Battery Drain with lots of homework done!-meter.jpg

3. Is the 18 mA draw from trailer break controller significant? I've had the controller for years, and only just recently had the battery problem. Could controller be going bad?

4. Would you change the injector driver module (from fuse #27 under hood before messing with pcm?

NOTE: I know you have to wait for truck to go into sleep mode before testing draw. I think It was, but my meter would go to sleep too! When I wake up meter, does the pcm reset too?
 

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Discussion Starter · #5 ·
Excessive rust?
 

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Discussion Starter · #6 ·
Excessive rust under here
 

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Discussion Starter · #7 ·
We had a monster down poor last night.
Before it started, I wrapped a paper towel around the fuse box under the dash.
It was bone dry this morning.

Maybe only driving in the rain causes the leak?

I'm still going to pull the fuse box to look for water intrusion.
 
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