VWDiesel.net The IDI, TDI, and mTDI source.

General Information => Troubleshooting => Topic started by: mtnbob on August 28, 2012, 12:31:40 am

Title: New Engine Shorting Out the Battery??
Post by: mtnbob on August 28, 2012, 12:31:40 am
Just replaced my engine. It runs well, but the battery is shorting out. New battery, new alternator, both check out perfect. When I hook up my multitester, take off my positive clamp, and but one lead on the battery terminal and one on the clamp, I am pulling 12.9 amps. When I pull one fuse at a time, nothing changes. When I unhook all electrical connections on the engine, one at a time, nothing changes. I have to unhook my battery at night to keep it from discharging :o

Any suggestions on the next step??
Title: Re: New Engine Shorting Out the Battery??
Post by: burn_your_money on August 28, 2012, 05:40:40 am
Did you unhook the 12v power cable to the alternator? Did you pull all the relays?
Title: Re: New Engine Shorting Out the Battery??
Post by: Rabbit79 on August 28, 2012, 07:40:05 am
Sounds like you're on the right track, you just need to move further upstream. I'm not sure on a MK 2 but on mine there's a single wire that provides power to the fuse box, hooks up to the 'H' terminal IIRC. If you could disconnect that you could eliminate the fuse box and most of the wiring. I'd also pull the wire off the starter to see if that's where the problem lies.
Title: Re: New Engine Shorting Out the Battery??
Post by: mtrans on August 28, 2012, 10:41:01 am
I'd also pull the wire off the starter to see if that's where the problem lies.

X2 for your 12 Amp.
Title: Re: New Engine Shorting Out the Battery??
Post by: 8v-of-fury on August 28, 2012, 09:23:48 pm
12A Jesus!

I had 1.16A kill my battery over a 24 hour span.. 12A.. that is brutal.
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on August 29, 2012, 05:21:03 pm
Ok, I haven't pulled my relays yet. I have pulled my starter wire. I'm not sure about where the 12 volt main wire is??
Title: Re: New Engine Shorting Out the Battery??
Post by: Rabbit79 on August 30, 2012, 01:11:52 am
In some cars I've seen them come off the starter relay instead of right off the battery, but if you've pulled your starter wire you've eliminated whatever comes off of there. What I would do is disconnect every wire that comes off the positive side of the battery one at a time until the amperage draw goes away and then you'll have it narrowed down to one particular circuit. Then you can start tracing it out and see where it goes. Bentley wiring schematic would be very helpful for that part if you have it.
Title: Re: New Engine Shorting Out the Battery??
Post by: Toby on August 30, 2012, 03:29:52 pm
I suspect that the alternator has a shorted diode. The easy way to check that is to hook up the battery on a cold car and check back in 1/2 an hour. If the alternator is warm, you have found the problems.
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on August 31, 2012, 03:33:26 pm
Hmmmm interesting!! I will check it out. I pulled all of the relays under the dash, but it keeps pulling 12.8-12.9. The alternator was rebuilt and put in with the motor a month ago.
Title: Re: New Engine Shorting Out the Battery??
Post by: R.O.R-2.0 on August 31, 2012, 03:37:59 pm
Ok, I haven't pulled my relays yet. I have pulled my starter wire. I'm not sure about where the 12 volt main wire is??

the main power feed is one of the 2 smaller power wires off the battery.. i believe one is for the glow plug system, and the other is for the fuse panel..
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on August 31, 2012, 04:41:38 pm
Ok ty, I have definitely pulled that!!
Title: Re: New Engine Shorting Out the Battery??
Post by: theman53 on August 31, 2012, 06:21:26 pm
Hmmmm interesting!! I will check it out. I pulled all of the relays under the dash, but it keeps pulling 12.8-12.9. The alternator was rebuilt and put in with the motor a month ago.

Just because it is new doesn't mean it isn't a problem, especially electrical stuff. I just wonder for 12amps if something wasn't hooked in backwards or something crazy.
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on September 01, 2012, 10:32:18 am
Anything is possible, since I did it myself ::)
Title: Re: New Engine Shorting Out the Battery??
Post by: Toby on September 02, 2012, 09:46:30 pm
Did you ever check to see if the alternator is warm on a cold engine?
Title: Re: New Engine Shorting Out the Battery??
Post by: mtrans on September 03, 2012, 11:39:11 am
I`ll check (unhook)starter motor and when alt.
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on September 03, 2012, 02:12:40 pm
Sorry, out of town for the holiday :)  I am checking it tonight, and will report back ::)
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on September 04, 2012, 10:56:27 pm
Unfortunately, whether the alternator is hooked up or not, I am still pulling a bunch of volts when the car is off. I still have to unhook the battery when I stop. Any other ideas?
Title: Re: New Engine Shorting Out the Battery??
Post by: Patrick on September 05, 2012, 03:06:06 am
I'm watching this thread too, got a similar problem. Quick fix is a disconnect switch that you put on the battery, then put the battery clamp to it. Still have to remember to shut it off though..... Like to find the problem. Wasn't the alternator in my case, changing it out didn't fix it.
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on September 05, 2012, 10:45:24 am
Ok, finally got to the bottom of this problem(hopefully). I finally gave up and took my Golf into the electrical expert in town. Turns out that the solenoid that I put in a few years ago, when I "pimped my glowplugs" was staying on after going through a start cycle. The mechanic didn't have any issues with the rerouting of the glowplugs to a more efficient system, but told me that these things can go unexpectedly. He replaced it with a new solenoid that would be used in an old Ford truck. It looked a lot like the one I had used before. The part cost me $20, labor was $65. Seems to work perfectly now. Just a heads up if anyone starts to have issues where there battery rapidly discharges. :o
Title: Re: New Engine Shorting Out the Battery??
Post by: burn_your_money on September 05, 2012, 06:40:07 pm
Glad to hear you got to the bottom of it.
Title: Re: New Engine Shorting Out the Battery??
Post by: theman53 on September 05, 2012, 06:41:56 pm
might want to change the GP now. I think warm they pull 12 amps each.
Title: Re: New Engine Shorting Out the Battery??
Post by: CRSMP5 on September 05, 2012, 07:03:50 pm
yep if it was staying on.. they be dead...
Title: Re: New Engine Shorting Out the Battery??
Post by: burn_your_money on September 05, 2012, 07:10:47 pm
Duraterms technically should be able to handle it, but the draw should be greater than 12amps.
Title: Re: New Engine Shorting Out the Battery??
Post by: theman53 on September 05, 2012, 07:14:09 pm
IIRC it was first cold glow they will instantly pull around 25 amps each and then settle to about 50amps for all 4, if they are good.
Title: Re: New Engine Shorting Out the Battery??
Post by: 8v-of-fury on September 05, 2012, 07:31:28 pm
I think I have read that duraterms (having self voltage regulating abilities) will drop down to as low as 9a each while hot.

I would think a 12a draw.. meant 3 of them were already dead by the time you even caught on to it being a drainage problem ;).

What brand GP's were in there? The guy who did the work obviously tested it, and it starts.. so they must have been fine?
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on September 05, 2012, 09:16:53 pm
I was told that they all were fine, but I will be looking into it in a few weeks.
Title: Re: New Engine Shorting Out the Battery??
Post by: Patrick on September 06, 2012, 02:56:54 am
I better check mine, maybe I have a bad relay doing the same thing....
Title: Re: New Engine Shorting Out the Battery??
Post by: mtnbob on September 06, 2012, 05:49:33 pm
Maybe check to see if your cold engine gets warm around the glowplugs when you hook the battery up. :)