The 8mm diameter wire, originally red, now “brown” in most our cars, is the primary voltage supply for all of the car accessories, lights, computers, etc, virtually everything.

I pulled an old wiring harness out of the attic to verify what I thought I knew. The subject wire goes to the B+ post of the alternator as well as the B+ on the starter. At the "other end" it of course goes to the jump post by the 14 pin plug.

As I understand the troubleshooting done by Bilal, he has removed the red wires from the jump post and still has the high current drain out of the battery with the “brown” wire connected. That suggests either the now “brown” wire is pinched to ground between the 3 points of connection, or the alternator or starter has a near short circuit. However, I am not certain that was what he has tested....as I read (and I have been known to be very wrong) if he removes the “brown” wire from the post then the voltage drop ceases. That suggests the problem is on the other side of the circuit, namely some place in the CE panel, CE panel wiring, or one of the multitude of fused circuits.

He states he has verified the subject “brown” wire is not pinched by any of the work done in the recent MM refresh....

My recommendations remains; do the easy stuff first….
1. Disconnect the battery ground cable from the car frame in the tool pocket
2. Remove all fuses from the fuse block…take a photo first to verify sizes and empty locations
3. Reattach the battery ground and check for a quick voltage drop
4. If no voltage drop, then reinstall the fuses one at a time checking the results of each, again looking for the voltage drop to commence. Leave the fuses in until the one is found that causes the excessive voltage drop. It should be very apparent with some arcing and sparking most likely when the fuse is inserted.
a. If there is the voltage drop with all the fuses out, then the difficulty has to be in the run of the subject “brown” wire, and that would include a pinch in the wire to the frame, or a defective alternator or starter, or one of the connections on the starter or alternator touching a grounded piece of metal
b. Or there are wires in the back of the CE panel or wire cables to the CE panel now burnt/melted together
5. If a fuse is found that does cause the draw then troubleshooting that circuit will be necessary, but that should be done with the fuse back out…..

 

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Niel,
OK, there are three wires at the post. The fat one that brings power from the battery and the 2 red omes that I suppose go to the circuit panel.
If everything disconnected, The fat red one to ground reads 17.77. The other 2 read to ground 1.3 each.
Thanks
Bilal

 

Now I am understanding how the circuit gets completed. So yes from the battery to the fat red there is no drain. The drain happens when I connect the fat red to the other two. So as you said it is somthing between the terminal and the CE panel. So where does the wire from thr post to the CE panel run? I want to check that and see if that got pinched.
Thanks
Bilal

 

[quote] Niel,
OK, there are three wires at the post. The fat one that brings power from the battery and the 2 red omes that I suppose go to the circuit panel.
If everything disconnected, The fat red one to ground reads 17.77. The other 2 read to ground 1.3 each.
Thanks
Bilal
{/quote]

A pinched primary feed wire suggests a dead short, which would fry the wiring and probably cause a fire. This is not as likely, IMHO.
Now try my earlier suggestion, leave the big wire off, leave the meter on as it is now on the two smaller red wires, and go start pulling fuses one at a time until that reading jumps back up from 1.3 ( hopefully).
Let us know what you find.

 

You guys are great.
OK, so I put the multimeter on the 2 smaller red wires and started pulling the fuses. When I pulled fuse number 25 (7.5A) the meter reads OL (Open line). That fuse is for "Diagnosis connect. Current pulse tailgate, inside light".
So I took the fuse out and connected all the red wires at the post. Then connected the battery and the draw is minimal and it is not discharging as before.
So now what?
Thanks
Bilal

 

Maybe your tailgate light has shorted to the frame - there are 2, one in the top of the tail gate, one at the base - carefully pop them out and look for the short - you are 99% there - congrats !
or leave the fuse out an drive, enjoy!

 

Are these the tail lights / driving lights or the interior lights at the tail gate?
Bilal

 

Interior lights at tail gate - leave the fuse out, hook everything else up, and test the tail , driving lights. I'm sure these are the interior on the tail gate - I had the same problem on my 86 - light just inside tailgate, on the right as you look in, was self destructed!

 

6
OK with this info you should disconnect the battery,
and then remove all the lights from the interior,
and put a piece of heatshrink on every lead that goes for the grounds as well as the power leads,
next check for continuity to ground on all of the power wires if you find this then the interior light harness has melted and is grounding.

the light harness is connected to the CE panel IIRC on the last connector at the bottom right but check the WSM elex diagram to be certain,
then look along the passenger side floor where this harness runs see if you can find any melted wires, the short will usually be in the roof possibly near the light over the mirror

 

With fuse 25 out and battery disconnected., put the ohm-meter one side to chassis and the other side on each side of the fuse holder and look for the same short reading. Pop each interior light fixture out, starting at the tail gate, and look for the short to go away. Then trace it back -

oops, just saw Stan's post, another way of approaching same diagnosis.

I'm thinking of adding "I like electrical problems' to my signature :-)

 

OK, with the fuse out, battery connected I started the car. IT started fine, the voltage at the battery was 14.2 and all lights work. The only thing that was not working was the interior lights and the digital dash display (the mileage and info/alarms)
Will check all the lights.

 

You do not need to disconnect the battery again, use the voltmeter to find which side of the fuse 25 is hot ( +12) and the other side is the load.
With fuse 25 still out, put the ohm-meter one side to chassis and the other side on the load side of the fuse holder and look for the same short reading. Pop each interior light fixture out, starting at the tail gate, and look for the short to go away. Then trace it back -

 

I pulled all the interior lights and non of them are melted or broken. Put the fuse back and let the lights hang and everything is fine. The lights in each door when turned on draw the voltage down, but not as drastically as before. Shut the lights off and put all the lights back and there is no more draw.
Did not find a smoking gun, but now it starts and runs and does not have that draw that killed the battery.
I still have the car on jack stands and disconnected the battery for the night. I just want to be certain that I (we) found the problem before I button everything up.
Thanks for all the help.
Bilal

 

That sounds as if you moved the interior light wire that was shorting to ground, so that it is not now touching - but it might touch again when you hit a big bump...