Dead diesel truck!!!! HELP!!

[texags02]

Started my truck thursday night, battery was weak but it started, started it friday, was okay. Tried to start sat., dead as a doorknob. This has been going on for months. The batteries are interstate and were new nov. 05, so almost 2 years. Have had the batteries tested twice, alternator also, both test fine. Told that batteries were drained down. Had mechanic check it out, he cant find anything, told me to disconnect my aftermarket foglight and cd changer power that is hooked to aux. battery post. Said that maybe the relay on the foglight relay was pulling juice even when off. I pulled that off last week, and it is still dead. My truck sits most of the time since I have a company vehicle. I had to jump it off last night, it was so dead that the cab light was dim. I got it started and drove it for about 10 minutes to charge it, cut it off and it fired right back up. So that makes me think the alt. is charging the batteries. Something must be draining them down. How do I go about with an elect. meter to determine if something is pulling on the batteries when the truck is off, then how do I find it?
Someone suggested this:
I disconnected one battery and the negative terminal on the other battery. I put my multimeter on the negative terminal and the negative cable of the battery that is still hooked up. I was showing 11 volts. I pulled every fuse under the hood box one by one, under the dash, and the fuse panel on side of drivers dash one by one. The 11 volts never went to 0. I did the same thing with the other battery and same thing. Something is till drawing from the battery when it is off. Is there anything that does not go through the fuse panels? HELP!!!!

[texags02]

Nevermind about the volts, I did that wrong, should have tested amps

I disconnected the one battery and the positive on the other battery. My meter is showing a 2.15 amp draw between terminal and cable. I pulled the 15A radio fuse in the under hood fuse panel, and it went to .8A. I then proceeded to pull different ign and inst. cluster fuses till it went to about .17A That was only under the hood fuse panel, didnt check the other ones. I have a stock radio. Should the memory or computer in the truck be drawing some amps to hold its memory? Is this about the standard amp draw or is this abnormal?

[kaylabryn]

8 amp draw for everything on board sounds about right but 2+amps is high. At that rate a 200 amp hour battery would be dead at less than 100 hours or 4 days. Granted you have 2 batteries but still.

Couple questions was your key completely off when doing your test? I assume yes but. Also you need to verify with a schematic that the radio fuse only goes to the radio. Where I work we had a Dodge truck that did the exact same thing it ended up being our trunking radio ground near the antenna which was grounded at the dome light. That was creating a strange grounding problem that caused the drain. I also know that a corroded ground can cause power consumption.

[DmaxMaverick]

How long is it sitting?

They do drain after a time of sitting. And it's normal. If it's happening after a couple days, you have a problem. After a couple weeks, it will drain significantly. If you have a situation requiring you to not drive it for long periods, there's a couple things you can do. Isolate each ground with a switch. A friend picked up manually operated battery a cutoff switch at Harbor Freight for less than $10. It looks robust, is rated for the current, and has a "key" for the connection. Also a good antitheft device. Stay away from the relay type isolators for your situation. Additional current load. Or install a solar maintenance system if it's parked outside.

[More Power]

There are several systems in the truck that remain powered up with the key off. The security system, wireless remote, OnStar, radio, retained accessory power, etc. are all powered when the ignition key is off - though the amount of current draw would take several months of inactivity to drain the batteries.

You did the right thing when removing fuses to check for current draw. The fuses that dropped current draw significantly are what I'd focus on for a problem. The door courtesy lamp switches have been known to cause this problem. I don't know what the typical draw should be... If the radio is the biggest draw, I'd suspect it.

I've had a truck sit for 3-4 months without the batteries draining to a p oint the engine wouldn't start.

Jim

[texags02]

yes, i had the keys off and dome overide switch on to stop the cab lights. The truck usually sits the most about 4 days at a time. Is there a way to find out what the draw rate should be? Also, what grounds should i check and where are they?

[NutNbutGMC]

Not to be a smart aleck but here's what I keep plugged in on all of the batteries here, now that I have acquired the product (after asking a bit of info here).

http://www.batterymart.com/p-battery-tender-plus-12v-1_25a-battery-charger.html


Daily drivers probably don't need this but I do not drive mine near as much as I did the previous machines (due to less work travel). This 07 sits a lot, thus my concern for the batteries. Optimas will be their replacement as soon as another GMC in the Hood goes bad.

[MEP]

You have what isknown as a "Parasitic drain". There is an excellant GM TSB about this. The TSB # is: 02-06-03-010A, dated July 02, 04. Here is some info from it.

"The recommendation for maximum parasitic drain is around 30 mA (0.030 amp). A typical drain today actually falls into the 7-12 mA range, even though some vehicles do approach the maximum. Multiply the drain (in amps) by the time (in hours) the battery sits without being recharged. The result is the amount of AH consumed by the parasitic drain. The actual drain may be small, but over time the battery grows steadily weaker."

[mr. monte]

battery tenders are great things too

[texags02]

Replaced both batteries on Friday, everything has been fine since then. Thanks

[Mark Rinker]

How many days do you expect to be parked before the new batteries will also be dead? 5? 7? 12?

The battery tender is the best solution for your situation, IMO. Leave all the stuff on, keep your batteries high and tight, and enjoy for a few cents a month on your 110AC bill...:D

[Turbo Al]

Removing Interstate as possible choices when I need new batteries LOL. Actually was told not to buy them by our shop mechanic.
Al