97 7.3 f350 auto 2wd dually Brand new batteries , both completely dead within 2 hours of the truck shutting off. When pulling batteries out I noticed the cables were pleasantly warm to touch in this freezing weather. I have code p1396( glow plug monitor fault) and p0381 (glow plug indicator) and p0603 internal control module.

I have had these codes but the parasitic draw is new. I’m not to familiar with diesels so before I start throwing parts at it (glow plug relay, glow plugs , valve cover gaskets and wiring )

 

Get a clamp meter and start pulling fuses one at a time

 

Look up how to do a parasitic draw test with a multimeter. Not difficult To do, a little time consuming
Faster, better, and much cheaper than throwing time and parts at it

 

Here is a good site I have used in the past when testing for a parasitic draw.

https://testmeterpro.com/parasitic-d...-a-multimeter/

 

Not knocking a circuit draw test, but that sounds like the glow plugs stuck on somehow, either relay or controller. You have some serious amp draw to heat up the cables and/or drain new batteries in two hours. Headlights on over 4 to 5 hours on not-new batteries still left a normal start for me. Might start the search with unhooking one of the high-current wires (either positive feed from battery, or switched positive to the glow plug harnesses), and use a meter to see if that stops the draw. If yes, then diagnose if the relay is stuck on (low resistance across the switched terminals with the low-current signal wire disconnected), or it's a control problem (constant signal from signal wire).

If glow plugs aren't the problem, I would check battery cables to see that there isn't an inadvertent short, like a positive lug touching a hold-down or other grounded part. Might even be an insulation crack in the cables that opened up and shorted out when you moved the cables for battery installation.

Personally, I would do a fuse-by-fuse draw test last, after checking glow plugs and battery cables. My reasoning is that you have a very high draw that should exceed the capacity of most fuses. Looks like batteries for these trucks will be around 2 hours reserve capacity (defined as 25 amp constant draw). With 2 batteries, that gives you 100 amp hours total. If it's 2 hours from fully charged to dead, that's 50 amps. But allow some "fudge" for new batteries not fully charged, some charge remaining but not enough to crank, cold weather reducing capacity, and maybe it was more than 2 hours... current draw likely is less than that calculation. But you see the point... you're looking for enough current that should blow smaller fuses or start a fire in smaller wiring... not your glovebox light stuck on. I would check the "big" wiring first.

 

I am with Paddler.

Unplug glowplug relay and go from there. If still same, alternators can cause a large draw too if always 'excited'

 

Had this problem on a friends 7.3. I was helping him figure it out. First thing I did was new change on the batteries hooked them up and left the truck off. Put a test light to the glow plug side of the relay and sure enough it was stuck on with the key off. New one fixed the problem

 

If it turns out to be the GPR this might help... On the SD side of the moon the White Rogers/Stancor GPR has been a popular upgrade to the OEM GPR. Recently, an FTE'r informed us of the "Trombetta 684-1241-212" which fits in the OEM location (SD) and has the reliability of the White Rogers/Stancor.

If none of this applies to the OBS, please ignore my rambling...

 

You have good suggestions on finding the draw.

If it turns out to be the GPR, get a Stancor. They are great relays. I have had mine for over 10 years and it still does a great job. It is super easy to replace.

one thing I want to note is that the Stancor is rated for continuous duty, not intermittent use like most glow plug relays. This is why the Stancor does a good job and is well favored

 

I hadn't thought of the alternator. The wire plug on the top of the alternator is vulnerable to the wires breaking just behind the connector. It's too easy to lay something heavy (including yourself) on top of the alternator, and bend the wires until ultimately they break. Could have a short there.

But my bet is still on the glow plug circuit, specifically the relay. But do test before throwing parts.

 

To drain two batteries dead in that time frame, something would be on fire. Glow plugs would be the only thing that makes any sense.

 

https://www.dieselorings.com/1994-19...lug-relay.html They have tons of other bits you probably need anyway. CCV orings for example. IPR seals. Turbocharger to plenum o-ring.

The alt would pull the G65 battery down in my ex's Scout 2 really fast. Six hours and it would not crank, but could be jumped. The pigtail to the Delco 10SI was simply reversed as the keyway was broken off...same thing happened on my pal's '71 Cadillac in high school.

Anyway, glad you fixed it. That is what this forum is about.

 

so test terminal with brown and yellow wires? #4

 

Yes just to see if it has power when key is off then it’s stuck on

 

well I think the glow plugs have been staying on. Key is inside on my desk.