sheepfaced

Bad Short

30 posts in this topic

So I have a short after replacing the alternator, pulled apart sam and all good whith no pins on wires looking bad.what I did find was that there was 12.3 volts from my neg cable to the ground bolt on the frame. I have spent 5 days chasing wires that may be touching the frame and can't find anything. Has anyone come across this.

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You already said that:

 

Glad this memory thing is not just me. :)

 

 

 

 

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Start disconnecting every plug you can find one at a time until you see no 12.3 volts where you now see it....faster way is to pull all fuses and then replace them one at a time, noting which one turns on the 12.3 again....IF you yank all fuses and it's still there now you may have a problem...?  I hate searching for electrical gremlins...!

 

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So I pulled out the Sam unit and the ECU and starter the only thing I have not removed was the Alt but it was freshly rebuilt  for 225$. Please help  if any Idea

 

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Did you unplug everything or remove them..?  You only need to unplug things....once you have unplugged everything you can find OR if after one thing the short goes away then you know that's the issue.....you will need to start plugging in things one at a time until the short shows up..OR....plug one thing in, see if it shows the short and if not keep that unplugged and move onto the next item.  IF the short is still showing after unplugging all your items, the short is in the wiring harness somewhere and now you must search it for rub spots or crushed sections....like I said a night mare!!!

 

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2 hours ago, sheepfaced said:

he only thing I have not removed was the Alt but it was freshly rebuilt  for 225$.

 

dont take it out

 

disconnect the large power output wire then see if the short is gone

 

 

btw you could have got a new one for under $200

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I have taken out the sam and ecu and have unplugged every plug I can find. I have removed the Alt and diconnected the starter. Still from my neg battery cable to ground nut on frame is 12.3volts. I love my car but ready to burn it. Any ideas will help

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Is it possible that I have a wire with a Diode in it that is blown. With the alt out and red and black leads from alt bolted together still 12v draw

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Definitely could be a blown diode that was my first thought. I can think of several ways to narrow down the location of the problem maybe a friend has an induction coupling for amps ? 

 

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Thank You, that's a great Idea now that I looked up what that was. I am going to try and make a Diode wire first because I have just about checked every wire in that car with my meter. Thanks Mike

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Are you just measuring 12.3 volts with a voltmeter between the negative terminal and the frame of the car with the negative terminal disconnected and assuming it should not be there?

 

That is not a short it is normal.


The proof of a short is the mother of all sparks when you try to put the negative wire on the battery but putting a bulb in there is a better way to test.

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Hmmmm...????
Wait a minute....is this what you are doing...? Placing the volt meter pos on the pos battery terminal and then toughing the frame or body and getting 12 volts?  This would be correct to get this result no.....UNLESS...you don't have the neg battery attached to the car body or frame...?...lol.  IF it is attached to anything at all besides a pos location you will get the same result.  No...?

Without me rereading all posts....yes I'm lazy ....what is the issue...is the battery draining over night or in a couple of days?  If so yes there is a draw of power and pulling all fuses initially should find the short. As all power should be directed through fuse box then out to power items. IF you are still getting a draw or short after removing all fuses then there must be a short between battery and fuse panel....?  I do not think there is any item requiring pos feed that hasn't got a fuse in line somewhere. So removing all fuses should locate that short, no? 
IF this has happened all after the new alt then maybe it is a defective alt..?  Is it happening when car is not running, if so unplug alt and check again...if it still is happening then it's likely not the new alt.  Has there been any add ons that you haven't known about or seen  such as security or lights or ...?  Nothing out of the ordinary as in stock wiring harness..????  
Another thought here is remove the main pos feed wire off the SAM and see if the short still exists....this will eliminate the SAM internals being the short. 
Have you checked the small white connector that lives in the battery well that leads to the front...? It gets all corroded with green and white fuzz.  Same goes for the small silver box transport Canada installed  to make themselves happy importing these cars. Open it up also. Again check every grounding pin you can find by removing all eyelets and cleaning and then dilectric greasing each  to help keep them from corroding in the future.   Thanks MB.....Way too much electronics for such a supposedly simple car!

I know the mental strain when hunting electrical issues....IF I can't see a problem my brain has a terrible time with it....electronics fall into this black magic area....augh...

Good luck and keep us informed as we all learn from other's problems....thanks.


IF all this has been already done please disregard this post.....

 

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Ok, first things first, Thank You All, so it looks like the Alt rebuild place changed the regulator in my alt to a different regulator from the original one that was in my 450 from the start. The alternator was testing fine on the bench there, tested twice good in there shop but he came clean about replacing the Regulator with something different, put that alt in my 450 and it causes a dead short, went to the wrecker and bought one out of a 06 450, works perfect, no short. Engine out and in 6 times, very handy with my meter after checking every wire, know how to pop Sam and E-box and ECU now, also know how to contain anger and stress. Shop gave me my money back, became friends with wrecking yard.

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Hi again, so my draw is back, took off red wire from battery that leads to Sam unit 12.6 volts still there when voltmeter is connected from neg battery terminal to frame ground bolt. Reattached sam unit wire and took all fuses out one at a time, still there, removed E-box and still there, drains new battery dead overnight. 

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Have you checked the power leads going to starter or starter itself?  When you changed your alt maybe the wires got pushed up onto the engine ?

OR maybe the starter got shorted and now has a short?  There isn't much wiggle room when dealing with the power wire that joins the starter and alt seeing as they share the same power cord.

Check the length of that power cord all the way from battery to starter/alt location..?

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Posted (edited) · Report post

Everything looks great, I purchased a endoscope camera so I can see everything. I did crack open the sam and all things inside are all good, some little holes in ribbon wire, I am going to open up the E-box from Zytech and check that out when another problem occurs,  I have had 3 keys for years and they all do nothing even with fresh batteries,  no lock no unlock, can't take key away from dash, ZIP. 

Edited by sheepfaced

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know anyone with a flir tool?...

 

ive seen people use them to find hot spots like shorts in wires and sticking relays 

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Never heard of one, was going to try taking the ECU out and pulling it apart to check it. I guess I am trying everything before gutting my car and replacing main wiring harness,not even sure if that would fix it

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I have put nothing aftermarket on my car except 3 years ago I took out the cigarette lighter and put a double usb plug in its place. The grundig radio did cut out at times but didn't bother me.I do have the old bare ground wire on the back from engine bay to motor

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2 hours ago, sheepfaced said:

Never heard of one

 

its a heat camera...if you have friends or family in the hvac industry or in firefighting they might have access to one....it will show what components or wires are warmer than the others...whatever is using the amps will be warm

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Could you use a heat sensing gun like the ones used on engines etc or aren't they sensitive enough to pick up the small temp difference from a short?  Just a thought...?  Those you can get from Princess Auto for smallish money.
IF you have armed the lock out of the theft  device under the gear thick Immobalizer, finally came to me....augh!!!!   You will need to reteach your keys using a STAR machine I'm afraid.  Sort of sounds like this has happened as best I can tell from across the country over the phone so to speak. The old ground wire should work as long as it's in good condition, if not replace it with something like a #4 welding size wire.  Again 2 feet at princess Auto. Cheap....and they also sell the crimp on connectors....if you do not have the cvorrect tool a very dull chisel and a big hammer will get the job done.  

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Here is a pic of the ribbon wire in my sam, not sure if there should be actual holes in it. Car is driving me Bonkers. Thanks Mike

Screenshot_20220711-164603_Photos.jpg

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Took a few more pics, its very ripply where it opens up and then there's the holes

Screenshot_20220711-170745_Photos.jpg

Screenshot_20220711-171004_Photos.jpg

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