# Battery Drain



## buddymanzpop (Nov 14, 2009)

2004 GMC 3500 DRW, electric hydraulic dump body, 6.0 gas. 3 plug fisher, brake controller, dual battery set up, if the truck sits for a weekor so it will not start with out a jump or a charger to recharge the battery, the voltage drops to 5 amps and will not start, the auxiliary battery seems to hold proper voltage, the battery at the front is new, I did not replace the aux. battery because it would be 12+ volts, I had to replace a bad module that would not shut the lights of after delay but that was about two years ago, I checked and they do go out as they should but I always use the headlight switch to cancel the delay anyways. Has anyone seen anything like this before or have a clue as to what it could be? Also,sometimes I have to move the shift lever to get the key out of the ignition after shut down.


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## 2COR517 (Oct 23, 2008)

Voltage drops to 5 amps? That doesn't make sense.....


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## brad96z28 (Aug 21, 2005)

Does it have onstar? I would disconect each battery and load them them seperate, new or not.


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## buddymanzpop (Nov 14, 2009)

2COR517;1484814 said:


> Voltage drops to 5 amps? That doesn't make sense.....


No, it dosen't make sense, it should read 5 volts, and Brad, no it does not have Onstar.


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## peteo1 (Jul 4, 2011)

If the brake controller has a light on it, it could be staying on and drawing down the battery. It would probably take a few days to do it. I've only ever heard of that happening one time though. Depending on how old the 'old' battery is that could possibly make difference too. If you have two batteries you're supposed to replace both of them at the same time otherwise one will charge more than the other rendering one of them bad. If they're both still good then check the alternator output to make sure its working properly. Hope its not an expensive fix for you. Good luck.


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## RLM (Jan 12, 2006)

My 2004 & father in laws 2003 we had a battery get dead cells would do just as your saying, both had dual batteries, replaced both batteries on each truck, no more problem.


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## 2COR517 (Oct 23, 2008)

Are the batteries trual dual batteries or is one of them an isolated auxillary battery? Are you saying after the truck sits for a week one battery is at 5 volts, the other is at 12 volts?


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## buddymanzpop (Nov 14, 2009)

2COR517;1484903 said:


> Are the batteries trual dual batteries or is one of them an isolated auxillary battery? Are you saying after the truck sits for a week one battery is at 5 volts, the other is at 12 volts?


It looks to be a true dual set up (I bought the truck used in 08) the battery in the traditional place up front drivers side is new and drops in voltage when sitting, the passenger side firewall battery seems to hold 12+ volts. When the voltage is low when I turn the key the cluster does not even light up, when I put jumpers to the new battery up front the cluster icons light up and the truck will start.


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## brad96z28 (Aug 21, 2005)

buddymanzpop;1485060 said:


> It looks to be a true dual set up (I bought the truck used in 08) the battery in the traditional place up front drivers side is new and drops in voltage when sitting, the passenger side firewall battery seems to hold 12+ volts. When the voltage is low when I turn the key the cluster does not even light up, when I put jumpers to the new battery up front the cluster icons light up and the truck will start.


Make sure to isolate the batteries then, test them. They should both be dead if you have draw, something does not ad up. It dont matter what battery you put the jumpers on as they are connected together. Disconnect them and test them.


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## B&B (Nov 4, 2006)

brad96z28;1485072 said:


> Make sure to isolate the batteries then, test them. They should both be dead if you have draw, something does not ad up. It dont matter what battery you put the jumpers on as they are connected together. Disconnect them and test them.


Not on an OEM setup. Pass side battery is only connected to the system when the ignition is on. That's why it doesn't drain.

Once you verify the driver side battery is good you'll need to start checking for AMP draw and pulling fuses. ABS module not shutting down on key off is a common one on those trucks. So is a faulty ignition switch.


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## buddymanzpop (Nov 14, 2009)

Just looked at the truck battery cables and the pos. lead from the pass side battery goes to a solenoid on the firewall pass. side then continues to the middle of the firewall and goes down behind the engine, I will have to get underneath the truck to see where it goes from there. This does not look like a true dual set up due to this solenoid. What B&B is saying is making sense on why only one battery is affected by the drain.


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## buddymanzpop (Nov 14, 2009)

Put the voltmeter and spent hours dc'ing power supplies, with the meter set to milA I'm getting a draw of 1.65 to 1.75 which is just too much pulled every fuse and relay with no significant drop in mil amps being drawn, I then dc'ed all accessories, ( plow wiring, brake controller, dump body hoist power supply, and disconnected the power feed to the under hood fuse and relay box with still nosignificant change, it probably dropped .25 mil amps which I attribute to what should be the normal draw, I am wondering if the starter which is working fine could be the cause of the drain, trying to get the ambition up now to go pull the wheel and inner fender to go after it.


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## tjctransport (Nov 22, 2008)

if it has a sunvisor mirror, check the tight. i just went through this last month with a tahoe. the switch in the light shorted out leaving the light on. since the visor was never tipped down, they did not notice the light on. it killed the battery for 4 months before i looked at it, and it took me almost3 days to find it. i unplugger the light and it has been fine since..


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## buddymanzpop (Nov 14, 2009)

No lights in the visors, just an SL Sierra work truck, nothing fancy with roll up windows and AM FM radio, does have AC though. I disconnected the battery leads to the starter and ignition wire to the starter and no change in draw, both batteries go to the starter. B&B mentioned ignition switches going bad and causing a drain, I pulled all the fuses labeled ignition, would this diagnose a problem with the ignition switch? I checked the battery that gets drained for continuity to see if it had an intrnal short and got 00.00 ohms. I just reread other posts here and haven't completly isolated batteries, I only disconnected one lead from the aux. D#*n it.


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## brad96z28 (Aug 21, 2005)

time to ck igniton switch, or u have a module not going to (sleep). Not sure if you can ck them with anything other then a tech 2.


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## buddymanzpop (Nov 14, 2009)

brad96z28;1485268 said:


> time to ck igniton switch, or u have a module not going to (sleep). Not sure if you can ck them with anything other then a tech 2.


Going into column today, I'm assuming I'll find a plug at the ignition switch and disconnecting it should tell me if it's the ignition switch or not.


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## REAPER (Nov 23, 2004)

Do you have the plow wired so it works with the key in off position? 
I have a 04 as well only it has a BOSS plow. When I had the wiring installed I told him to wire it so it worked with key off. After he did that I had the same problem of the battery going dead when I did not have the problem before. I had him wire it so it would only go on when key was in on position and that worked for me. No more battery drain since.


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## B&B (Nov 4, 2006)

buddymanzpop;1485164 said:


> disconnected the power feed to the under hood fuse and relay box with still nosignificant change


Disconnecting that lead kills every single electrical circuit in the truck. Only things remaining are those that are connected to the battery, ie any added on circuits wired to the battery directly....and the alternator. :waving:


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## buddymanzpop (Nov 14, 2009)

B&B;1485681 said:


> Disconnecting that lead kills every single electrical circuit in the truck. Only things remaining are those that are connected to the battery, ie any added on circuits wired to the battery directly....and the alternator. :waving:


This is where I am at now, if I dc the alternator with the lead to the fuse connected I get no drop in mA, if I dc the lead to the fuse box and then dc the alternator I get a significant drop in mA being drawn the moment the alternator lead is dc'd so you would think alternator but, with the alternator dc'd when I reconnect the lead to the fuse box the mA draw jumps back up to 1.77 (doors closed, ign. off, no under hood light) so i now reconnect the alternator so both the fuse box and alt are connected and not a change in draw still at 1.77, and vica versa now with both fuse box and alternator dc'd I reconnect the alternator and it jumps back up to 1.77 mA then reconnect fuse box so both are now connected and no change. I place the multimeter leads between the alternator and alternator lead and get a draw of roughly 1.50 mA but this fuse box thing has got me really puzzled, so I dc'd the alt. last night , took a voltage reading from the battery and will compare that votage reading to waht I get today to see if it drops. Oh, the auxiliary battery had a blown 40 amp AMI fuse under it so I'm thinking that isolated it from being drawn down.


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## buddymanzpop (Nov 14, 2009)

Correction, the 40 amp blown fuse is protection for a lead that goes over to the under hood fuse box, it looks as though the solenoid on the firewall is what seperates the pass side battery from the starter where it meets the drivers side battery lead. Now I'm wondering if the solenoid is bad and that could be why the aux battery does not come to help in starting when the drivers side batt is low, I'll have to wait for a key turner to show up to check that. Overnight drop with alt dc'd was roughly .10 V (12 hrs) will now connect alt and moniter V drop.


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