Need help ASAP, fuse short

[dimixtron]

As the title says, I'm shorting out the 20AMP fuse which goes into the wiper slot on the driver side kick panel. I'm not sure what's shorting it, but it's causing a huge issue for me as I've figured out, for some reason, my fuel pump seems to be somehow connected to this fuse. I don't have any idea where to begin and I've looked searched around to no avail. If anyone could give a point in the right direction that would be great. I know it's a loose wire because it happens when the car hits a large bump which I assume created contact and shorts the fuse. I have a feeling for it to be somewhere in the rear because it happens when the rear dips (has happened twice on the exit I take to go to my restaurant). I've been driving the car on and off for a year now (only have put 800 miles since the 1jz swap)

Thanks in advanced for anyone who takes the time to chime in and have their 2 cents.

-dimitris

 

[mirage83]

That's a little strange to say the least. As you note the wiper fuse is in the drivers kick panel, but the EFI fuse and the related wiring starts in the engine compartment.

What's the car doing that leads you to believe the fuel pump is somehow connected or shorted into the wiper fuse block?

 

[dimixtron]

That's a little strange to say the least. As you note the wiper fuse is in the drivers kick panel, but the EFI fuse and the related wiring starts in the engine compartment.

What's the car doing that leads you to believe the fuel pump is somehow connected or shorted into the wiper fuse block?

Well once that fuse shorts out my fuel pump turns off, in turn I get no fuel and my car stalls out. Sometimes I'm lucky and to grounding is only for a second which causes the short and I can replace the fuse which then allows power to the fuel pump; or it stays grounded and every time I replace the fuse it pops on On position. It's an aftermarket walbro not installed by me, is there any way they taped it into the wiring for the wipers?

 

[hvyman]

Sounds like they did. I would go over the wiring.

 

[dimixtron]

Sounds like they did. I would go over the wiring.

Only issue is; where do I start? Wiring has never really been my friend. I know that access to the fuel pump is located by the spare but I didn't see any shoddy wiring there

 

[suprarx7nut]

I've done my fair share of wiring diagnostics and it's no fun, but there's no short cut. It's a pain, but worth taking time to sort out.

Start at the fuse you're blowing. Search the area around that loom for any modified wiring spots. Look for anything that looks out of place. Extra electrical tape, weird loom (plastic black stuff covering the wires). It'd be helpful to let it idle (or just leave the key "on" if that sets it off too) and poke around at the wiring. Move the harness, slap it with your hands, anything to simulate your "bump" failure. You may find the area of bad wiring that way.

If that doesn't work I think you'll need to get familiar with the TEWD. It's a great resource and it's free.

Front wipers:
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=080

Rear wipers:
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=082

Wiring routings:
Front
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=023
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=24

Back:
http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=25

You could literally wire the entire vehicle with the information posted for free in that website. You need to learn the "language" of the wiring diagram, but that's time WELL spent if you have a car with wiring issues. This likely won't be your first problem in wiring.

Good luck and keep us updated!

 

[super51fan]

Plus one to what he said. ^^^

Another good thing to look at is the POWER SOURCE section of the EWD. The 20A wiper fuse is supposed to power three things. Front and rear wiper and headlight washer.

As you can see on the other hand the 7.5 gauge fuse runs about half of the car.

Most electrical problems can be fixed by removing the added on crap some one added.

My best guess is that they liked the 20 amp fuse to run pump.

Sounds like you have a short to ground. Look at the added on stuff. Good luck.

 

[dimixtron]

Plus one to what he said. ^^^

Another good thing to look at is the POWER SOURCE section of the EWD. The 20A wiper fuse is supposed to power three things. Front and rear wiper and headlight washer.

As you can see on the other hand the 7.5 gauge fuse runs about half of the car.

Most electrical problems can be fixed by removing the added on crap some one added.

My best guess is that they liked the 20 amp fuse to run pump.

Sounds like you have a short to ground. Look at the added on stuff. Good luck.

My question is, from the rear where would I start exactly?

 

[dimixtron]

Should I start removing interior and checking wires like that? And then after I find and fix the issue, how should I go about rewiring it?

 

[suprarx7nut]

First things first. I'd start at the fuse box. Which is the left kick box. You can take out the interior trim piece around that box pretty easy. Take a good, hard look around that area. That's a common spot for people to tap into wiring.

What makes you think rear? I'm not 100% convinced the wiring mistake is necessarily in the rear. There's a lot of wire between the 12V battery up front and the fuel pump in the back.

How you fix it depends entirely on what is wrong. You can't plan how to operate before you know what's wrong with the patient.

Edit: This may also be helpful. Pretty generic info, but perhaps helpful. http://yotamd.com/toyota/sw2_mr2/harness.html

 

[mirage83]

As Super51 said, someone probably mucked around with the pump wiring (for whatever reason) and tied it into the 20A circuit. Drivers kick panel is the place I'd start, looking for any electrical tape, crimp connections, or even just some bare wire wrapped around another wire where the insulation has been cut away. Somewhere, a bare, uninsulated section of wire is touching something it shouldn't. Also, look for a wire not in a bundle of them, coming from out of nowhere. If they've run a new wire to power the pump, it'll be under the dash somewhere I would bet.

People do some really stupid things just to get a car running sometimes, and that what it sounds like with your issue.

 

[dimixtron]

As Super51 said, someone probably mucked around with the pump wiring (for whatever reason) and tied it into the 20A circuit. Drivers kick panel is the place I'd start, looking for any electrical tape, crimp connections, or even just some bare wire wrapped around another wire where the insulation has been cut away. Somewhere, a bare, uninsulated section of wire is touching something it shouldn't. Also, look for a wire not in a bundle of them, coming from out of nowhere. If they've run a new wire to power the pump, it'll be under the dash somewhere I would bet.

People do some really stupid things just to get a car running sometimes, and that what it sounds like with your issue.

I just assumed from the rear end bouncing that it would have to do with that, like I said I'm not electrical friendly.

Although I will be taking a look at the TSRM and my friend who's an aviation tech is going to help me track the problem. Gonna start later on today after 6:30; so if/when I find anything I'll post back with pictures and fixes!

Thanks again guys for the help and information, I really appreciate it.

 

[jdmfreak]

Are you sure it's just your fp losing power? The tccs controls the fp relay if you shorted the wire/blew the fuze going to your tccs the fp would shut off

The tccs is powered from the ign fuze in that same fuze box (jb1 iirc) as the wiper fuze

 

[dimixtron]

Are you sure it's just your fp losing power? The tccs controls the fp relay if you shorted the wire/blew the fuze going to your tccs the fp would shut off

The tccs is powered from the ign fuze in that same fuze box (jb1 iirc) as the wiper fuze

Positive -- everything else stays in and active and only things that lose functionality are whatever the wiper fuse controls plus the fuel pump. I have a 1JZ swap so my ABS doesn't work but I have checked and replaced all fuses anyways. Some relays do need to be replaced just because I think age wise they should be but they are not showing any problems.

UPDATE:
So I checked and played with all the wires with the car in on position trying to get the fuel pump to shut off and nothing yet. My next task is going to be to unbolt the fuse carrier in the kick panel and see if there's any loose connections behind it. I've come to realize my wires are all over the place, some exposed, some leading to nowhere, etc; but I may need to just rewire everything just to be safe and sound.

A task I am definitely dreading.

 

[suprarx7nut]

Positive -- everything else stays in and active and only things that lose functionality are whatever the wiper fuse controls plus the fuel pump. I have a 1JZ swap so my ABS doesn't work but I have checked and replaced all fuses anyways. Some relays do need to be replaced just because I think age wise they should be but they are not showing any problems.

UPDATE:
So I checked and played with all the wires with the car in on position trying to get the fuel pump to shut off and nothing yet. My next task is going to be to unbolt the fuse carrier in the kick panel and see if there's any loose connections behind it. I've come to realize my wires are all over the place, some exposed, some leading to nowhere, etc; but I may need to just rewire everything just to be safe and sound.

A task I am definitely dreading.

Yeah, I'd wager you'll need to go through just about all the wiring. It's a big task, but on a JZ swap it's probably worth doing.

This is one reason why I'd be *really* cautious about buying a car with a JZ swap (or any major motor swap) done at home or a no-name shop. Doing all the wiring "right" in a project that big is hard and lots of folks take shortcuts. Those shortcuts will take hours and hours to sort out after the fact.

Good luck! Maybe I'll get motivated to update my site with Supra specific wiring soon and it'll be useful. Probably not too much for a JZ, but some of it would still be good to know.

 

[dimixtron]

Yeah, I'd wager you'll need to go through just about all the wiring. It's a big task, but on a JZ swap it's probably worth doing.

This is one reason why I'd be *really* cautious about buying a car with a JZ swap (or any major motor swap) done at home or a no-name shop. Doing all the wiring "right" in a project that big is hard and lots of folks take shortcuts. Those shortcuts will take hours and hours to sort out after the fact.

Good luck! Maybe I'll get motivated to update my site with Supra specific wiring soon and it'll be useful. Probably not too much for a JZ, but some of it would still be good to know.

Well I've owned the car since 2008 and I had the swap done. It was done last year around this time by Sideways Performance in Santa Ana, CA. Rob did great work on my car, but the existing wiring issues were already there under the dash. Previous owner thrashed it with wires everywhere and poorly done, most likely by himself or a cheap place so many things I actually removed. I've been slowly trying to restore and upgrade the car at the same time. The fuel pump unfortunately was done by a shop by my restaurant while I was busy for pretty cheap, as now look where I'm at. Lol

Keep you guys updated when I find something.

 

[f00g00]

The fuel pump is accessed by dropping the fuel tank where you have access to the hanger, the sending unit is accessed from under the rear tire cover.
If you can get under the car you can check the wiring coming out of the tank, a lift or a pit would be ideal.
The fuel pump relay is on the right fender and is easy to look at the wires there.

 

[dimixtron]

The fuel pump is accessed by dropping the fuel tank where you have access to the hanger, the sending unit is accessed from under the rear tire cover.
If you can get under the car you can check the wiring coming out of the tank, a lift or a pit would be ideal.
The fuel pump relay is on the right fender and is easy to look at the wires there.

Well the fuel pump relay I haven't been able to find..considering tang using the swap various things were moved around to keep the engine bay "clean." So I need to find out what it looks like so I can check it out. Access under the rear tire? The spare? My initial plan now seems to have become to completely gut the interior so that I can fix whatever wiring is there, clean things up, and since I'll be going over everything may as well replace my dash since I have the replacement sitting in my garage

 

[jdmfreak]

The fuel pump relay on the passenger side fender may have been removed and bypassed (which is fine its called the12v mod) you need to find the circuit opening relay http://www.cygnusx1.net/Supra/Library/TEWD/MK3/manual.aspx?S=Main&P=46

 

[super51fan]

Do you own a multimeter? If not you need to get one. I suggest a fluke dm115, cheap only $145 on amazon. Easy to use. Even has min-max at this price. Gutting a car to look for wiring issues is as dumb as looking for a needle in a hay stack with out a metal detector. The same thing with a DVOM for finding wiring issues. Your eyes also, things that look out of place should raise concern.