HI everyone:

Ok, so I'm wrapping up the '02 LS1 into an '84 T/A engine swap, and the other week I was plagued by my starter not working. turns out it was the headlight low beam/ high beam switch causing the starter to not work. (somehow this must disrupt the starter circuit) So I solve this..

Now, my car has an electrical short in the system which blows out the 10 am "gages" fuse every time I turn the key on. It didn't do this before. It worked, the fuel pump came on and it pressurized the fuel system. At some point saturday morning this decided to short out. now it blows out and although I can now use my starter, I still can't start my car!

erghhhh!

The only things I installed this weekend are :

1- the headlight low beam/ high beam switch on the steering column.
2- the four oxygen sensors.

{regarding the 02 sensors, all 4 of mine have the "longer" wire, but this is how they came. I asked in an earlier post regarding is there a difference between the front and back ones, but mine are all the same size. does this matter? would this cause my short?}

After searching for obvious shorts (not finding any) and blowing up 30+ fuses trying to find the problem, I'm still stuck. I did discover that if I unplug the 7-wire plug in the back of the car (I installed the '02 factory plug for the fuel tank/ emmisions behind the back seat.) This disconnects the fuel pump as well as several other emmisions pieces. but lets the fuse live.

I also tried connecting these guys one at a time to see if a certain one of these was the culprit. (a wire plus the ground to complete the circuit) No luck. all 7 need to be plugged in to short the system.

When I install a new fuse, and turn the key to "on" I hear a tiny zap, then I hear the fuse blow out in the gauge panel. so it sounds like a direct positive to ground type of short.

I even tried installing new fuses last night (after dark) to look for a zap/ spark, but no luck.

any suggestions?

I think tonight I'll try disconnecting the headlight switch, then the 02 sensors to eliminate any other variables, but other than that I'm tapped on ideas.

and like I mentioned before, this did work earlier. I used to be able to turn the key on, hear the fuel pump pressurize, etc. now I can't. FYI I soldered all my connections, I used heat shrink tubing, and wired them one at a time to minimize crosswiring/ confusion.

thank you for your time!

-BV

 

i would almost say that you have too many things attached to that one circuit. it sounds like now that you have the head light switch and everything else on the same circuit and it is overheating it. i doubt you have a short somewhere if you have done all that work searching it out. you may just have toomany things on the one wire you found that turns on with the key. there are probably more positions on the fuse block that turn on with the key and i would spread the accessories out on them. maybe you have a short in the 7 wire plug itself. is all your equipment in working order still. did you fry the pump or anything? will it still work with a test lead? are you sure that big 7 wire plug is supposed to run everything on a little 10 amp fuse? i would try to find a seperate wire that is hot when the key is on. other than that i would get a thicker gauge wire and run it back there to the trunk and install a seperate fuse box for it. are you using any of the wiring from the 84 in this string of wiring? i would assume that there is a higher demand on the 02 wiring than there is the 84 for fuel pump since so much more pressure is required in the 02. if you are using the main wiring harness from the 84 it may not be strong enough. check and see what the fuel pump requirements fuse requirements are in an 02 vs 84.

 

OK, this is something I hadn't considered.

Yes, I've connected everything to the fuse block. There are several empty slots in the '84 fuse block . some are ignition powered, otheres are battery powered. I admit I have filled up every empty slot with the following:

LS1- "battery" lead (its own slot)
LS1- "Ignition" lead (its own slot)
autometer tach and speedo- "ignition lead" (both shared to one ignition slot)

the air pump needs an ignition lead, too, but it also has a relay in which I supplied direct battery power from, so it draws a lower power from the fuse block- also in an ignition slot which is sharing with one more emmisions accessory.

But, all the above is added to my fuse block.

Where else can I draw power from? Can I wire these up directly to the battery? Will this be too much amperage?

No, I don't think I fried the fuel pump, because I could swear I hear it on for one second or so before it cuts out.

It sounds like there's 2 "snap/ popping" sounds in the interior. one is the problem, the second is the fuse popping. It's this reason I'm wondering if I have a short somewhere.

I've removed all traces of unused wires from the old ignition system. the old wires were removed completely, so there should be nothing left for them to arc/ short out.

The '84 was carburated/ no electric fuel pump... so yeah, I'm sure this system is generating much more power draw than the LG4 305 ever required.

any suggestions on where to draw more power from/ how to set up a another fuse block would be greatly appreciated.

Thanks,

-BV

 

ok, unless you have a second fuse block, you're going to need to redo some of that in the intrest of safety...

if i read that right, you have the entire LS1 setup running off of two wires going into the fuse block......

 

just because it was carbed doesn't necessarily mean mechanical pump but ok. put your tach and the other low amp additions on the fuse block slot for your dash gauges and such also you may want to check your steering wheel wiring harness. my buddy has an arch out in his 85 mustang tilt wheel and when he moves the wheel his gauges start cutting out. maybe you have a short in the steering column and that is why you cant see the spark. i don't know. if it was working and now it is not after you put more onto that circuit, the only thing that really makes sense to me is too much juice through the wire. get a bigger wire and another fuse box. when i do my ls1 project i am going to be taking a complete wiring harness out of the donor car. would it be too late in your game to get an updated fuse block? maybe from painless or speartech or something. look in your steering column though and see if you do in fact have a short. if all your wiring is good get a thicker wire and run it all the way back. dedicate one ignition slot or even two to it. put a distribution block which you can pick up at any stereo store at the end of the wire somewhere hidden in the trunk. a two terminal unit should be enough and then plug the wiring into that.

 

OK, I'll investigate the fuse/ wiring.

I don't know that it's all on 2 circuits or not. I'll see where else I can draw power from. I'm not even sure which fuses the "ignition" and "battery" extra slots get fused at. (the "gage fuse, or another?) Does each "ignition" extra slot run on the same circuit? if yes, then I probably do have it all on 2 circuits like you say.

I hope the solution is this easy.

wish me luck.

Thank you!

 

You only have 2 wires providing power from the battery to the fuse block. There are probably 2 red #10 wires that attach to the large lug on the starter along with your battery cable. These two wires are the only source for power (constant and ignition) to your fuse block. I think that the extra slots in the fuse box are not fused at all. If you need to use a second fuse block in order to keep from overloading you current fuse block look in the FAQ`s at my post for the wiring info, both the 98 and 99-02 write ups in there have everything run off relays and a secondary fuse block so that no matter what car the motor is being swapped into there is no danger of overloading the fuse block.

 

Cool, thank you! I'll check those out.

Last night I had some success with the car- we did get it started and it was great to hear, but the electrical problem is still there.

There is a popping sound coming form where the old computer (for the LG4 305) used ot be. We took the panel off there nad looked for it, pullingthe wires down and sometimes the sound would be there, sometimes it wouldnt. We TEMPORARILY used a paper clip in place of the 10 amp fuse to search for the short (hoping this area would get hot to help us locate it) but we were unsuccessful. We couldn't find a hot spot. We also then installed a 20 amp fuse inthe location ofthe 10 amp and that popping sound would still happen by the old comp;uter location, but this timethe fuse would not blow out. The 20 amp fuse ouwld live.

So- if I'm correct then I've just overloaded the 10amp circuit, yes? (as mentioned before)

tonight I plan to remove as much of the old computer wiring as I can so I'm not running unnecessary wires with power in them in my car. I sure won't be reverting from an LS1 to a LG4 305, even the original one...

I think it would also be good to find another source of power for some of this- setting up another fuse block so I can return a 10 amp fuse to its correct location.

The LAST THING I want is an electrical fire. I lost a car in highschool to a fire, and I don't want to do that again.

I have the 4th gen battery cables in the car and I have that extra positive cable/ post set up. It would be an excellent source (good, heavy guage wiring/ insulation) for power...

Thanks,

-BV