Fuse keeps blowing, need help troubleshooting issue

[emericaskater285]

My car has been running great and working great the past two weeks or so now, until this issue shows up.

Here is what happened. I was out at the lake, just started my car after it sitting for a few hours while on my friends boat. Everything was fine as far as I could tell. I shut the car off after running for maybe three minuets, and turn the key to the ACC position to listen to music, the car is off for about two minuets. I turn the car back on, and I have no gauges working on the cluster, windows quit working, and A/C quits working, etc.

Here is what I have found so far. I know I have a short, but I am not sure where. I replaced the fuse, and as soon as I turn the key to the on position it blows the fuse instantly. I assume the short is somewhere between the 7.5 amp "gauge fuse" and obviously one of the loads after that fuse. I have tried to replace the fuse multiple times after trying unplugging different things(gauge cluster, a/c module, window switches), and am running out of patience.

Now, I realize that there may be a few other things not working. Including all of my gauge lights, reverse lights, windows, a/c, cluster gauges, pretty much everything under the 7.5amp "Gauge fuse" shown here. http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=32

I am trying to locate the next connections down the line from the fuse. I see that there is a connection at J/B 3 (junction block 3), tail light sensor, back up light switch, power main relay, and I believe that is it.

I have also heard it could be a wire in the engine harness getting burnt through, but I have checked over the harness, and see no holes or burns in it.

I have checked out this thread(http://www.supramania.com/forums/showthread.php?27803-Need-the-Electrical-Expert-Blowing-Gauge-Fuse), and also tried searching for other answers regarding my question, and nothing has turned up so far. If there is anyway I can get some help with this I would appreciate it.

Has anyone here had this issue, and solved it? If so how, and what are some things I can do to troubleshoot it?


Some things to consider, I have not changed anything recently wire wise or parts wise in the past week or so. This happened at two in the morning, and I just put my windows down when I first got in it, so they are now stuck open at the moment.

 

[Maple191]

well if you unplug all of those things at once and it still blows its a dead short from wire to ground. If you unplug them all and the fuse is still good, try plugging things in 1 at a time till it blows then look at that
circuit.

 

[Another MkIII]

Do you have a multimeter and test leads?
-AM3

 

[emericaskater285]

Do you have a multimeter and test leads?
-AM3

Yes sir. Looking at the tsrm, I am not sure where I need to start. I think I need to pull the "power main relay" and the connector at "junction box 3" Also may need to pull the tail light failure connectors too. I am thinking of starting there, and trying to isolate which circut makes it short out this time, then going from there.


The thing that just doesn't make any sense to me is that I haven't touched any of these wires, or areas in a long while (about a year or more) and all of the wiring is in great shape as far as I can tell.

It is just odd how the short came out of nowhere.

 

[jetjock]

Coming out of nowhere is what shorts do. Jumper the fuse with the biggest wire you have and it'll show itself (kidding...don't do that).

Try taking the advice in that other thread and use a lamp in place of the fuse. Or disconnect the battery and use your meter on ohms across the load side of the fuse and ground.

 

[emericaskater285]

Coming out of nowhere is what shorts do. Jumper the fuse with the biggest wire you have and it'll show itself (kidding...don't do that).

Try taking the advice in that other thread and use a lamp in place of the fuse. Or disconnect the battery and use your meter on ohms across the load side of the fuse and ground.

I actually did try the light. I put it in where the fuse is, and it seems to have full power(no extra resistance). I didn't get much sleep last night, so this may be a better project for tomorrow after I get a good nights rest, and get my head back on straight.
I will also get out my multimeter, and see if I can track it down that way. It is just a bit of a struggle. I was planning on going racing last night, but had my car torn back apart starting to troubleshoot this issue.