main fuse box surprises
 

Hey guys. I've got an 89 TII that previously had alot of work done to add a custom turbo setup. Apparently when this was done lots of stuff was yanked out and there was some rewiring. I'm slowly dealing with the fallout from that.

So, I recently was looking around under the hood when I noticed some smoke coming from my main fuse box... I killed the car and disconnected the battery. The smoke was coming from the egi plug. When I pulled the plug from the fuse box, I saw that two wires were running into the hot side of the fuse and there was no ground wire coming out. The body of the plug was scorched and decayed. When I opened the fuse box the fuse looked fine on the surface, but the underside of the fuse was similarly scorched. The fuse box itself is slightly discolored, but seems intact.

So, I started looking for pictures of an 89 fc main fuse box cover (saw the faq) and nothing matches my cover. Also, the fuses are rated for a higher amperage than my cover lists, and are also higher than the amperages I've seen online.

The cover says I need 30 amp egi and head fuses. 60 amp fuses are plugged into the box. My main fuse is listed as a 100 amp, not 80 like I've seen posted online. It's actually using a 100 amp fuse.

I've attached pictures of the cover, the box with all fuses in, the burnt 60 amp egi fuse and the destroyed egi plug.

Any advice on how to handle this? Is this the rigth fuse box cover? Do I need to hunt for an unattached ground wire? Can I ground it to the frame? I've got almost 0 experience with auto-electronics. I'm a speaker/computer guy.

Thanks!

There is no "ground wire" on a fusebox...power goes in, through the fuse and then out to the intended device(s).

The main fuse for an S4 is 80 amps, but you have an S5 so it would be 100 amps. For an S5 the BTN fuse is 60 amps, Head is 30 amps, EGI is 30 amps.

i would suggest finding a reputable electrical automotive shop to trace out the circuit. sounds like the fuse was bypassed since both wires run to the same pin on the fuse block, meaning no power is actually passing through the fuse but the circuit is definitely being overloaded by a short.

where the short is? is anyone's guess. the EGI fuse passes power on to the ECU, ignition coils, fuel injectors and all the 12V emissions powered devices on the engine harness so any one of those things could be shorting out to ground.

first step would be to visually inspect and see if you notice any wires laying on the block that are worn through and grounding out, next feel if the ignition coils are getting hot without the car even running. try to feel the wiring to see what wires are getting hot and leading from where. the point where the wire is shorting at, that whole length of wire to the fuse block/battery will be getting warm/hot.

@clokker: On closer inspection of the fuse box I saw the single 'in' line and all the other plugs just have the one line coming out. So yeah, no grounding. Thanks.

@satch: So it sounds like I've got the correct fuse box cover. great! Thanks!

@Karack: This car has a Haltech ecu. Could that be why the fuse was upped to 60 amps? If one wire goes to the original systems (- the ecu) and the other wire is running to the haltech ecu, could I split the wires and use two seperate fuse blocks? If so, could I just use two separate 30 amp fuses?

Thanks guys.

shouldn't need an additional 30 amps for the ECU. the haltech originally uses a 3amp fuse to give you an idea of how much amperage it pulls. the stock ECU probably pulled more amps than the haltech should. i could only guess that the intent was to power the relays and fuses for the haltech fuse/relay panel which power up the fuel pump, fans and other misc bits as well.

but we can only guess as to why it was upped and that still doesn't explain why both ends run to only the one side of the fuse. technically it would be the same running that EGI wire directly to your battery terminal. but i'm just throwing out ideas, i can't see if the fuse does in fact have a terminal on the other side, color wires or modifications to the fuse block, etc.

There are definitely two terminals in the fuse box. The two wires running into the plug are solid blue wires coming out of the wire harness. I've attached three more pics.

The fuse block doesn't appear to have any modifications to it.

The input side of the fuse box is closest to the battery. The other side is the output side. Is this how your's is?

EDIT: The EGI fuse has two output wires and both lead to the Main Relay.

The battery was moved to the passenger side storage area, behind the seat. They also removed the bracket for mounting the main fuse box. I found it just dangling in the engine compartment.

So those two wires coming out of the egi fuse are supposed to be like that? If that's the case, do you know why they might have started burning? Just a general short somewhere like Karack mentioned?

i don't recall any of them having 2 wires in a single connector but the 60A fuse is too much for that gauge wiring. looks like someone added a whole nother circuit to the EGI and something is now consuming too much power like a thirsty fuel pump or a poor idea of running an e-fan off that same circuit.

try simply following the wiring to where it leads, since it has been rewired that could be to anywhere and may be either simple to follow or very difficult.

If he had an S4 he would have two EGI fuses so each one would have its own individual wire but since he has but only one EGI fuse it has to route two wires to the Main Relay where one is W/L and the other is W/R. Now maybe it comes out as one then splits into two but if connector X-02 is not present then there would be two wires.

If you had the sides mixed up all you would need to do is measure for voltage on the single wire to the fuse box and see if it has battery voltage to it w/the fuses all pulled. If all the fuses were pulled then the only side receiving voltage would be the wire running to the fuse box from the battery. And this will help to differentiate which is the incoming side and which is outgoing. So see which is which before a diagnosis can be offered.

got it, but whatever the issue is here with the 2 wires joined they both now have a 60amp maximum capacity each before blowing the fuse, which is too much for the gauge wiring it has.

not sure if it is a complete short or a partial one or simply an overloaded circuit with too many accessories, a complete short would catch the wire on fire or blow out the fuse or both.

Go to the Main Relay bolted to the fender right near the trailing coil. Disconnect the plug w/four wires to it. Do the two wires coming from your EGI fuse match the color of two of the wires in this relay plug? The four wires in this plug are usually Black/Yellow, Black/White, White/Red and White/Blue. I'm going to guess you have the B/W and B/Y wires but not the other two, White/Red and White/Blue. So see what you have there.

Two wires come out of the series five EGI fuse. One is used to feed power to the alternator all day long key on and key off. As shown in the attached jpg out of the series five manual.

I'm guessing a hacked up alternator job is the cause.

Here's the burnt egi connector out of the plastic chasis. You can see where where they soldered on new wires. The original wire is short and burnt so I'm not sure about the colors. Looks like it might be red/black, yellow/black? What do y'all think?

I'll check all the other stuff y'all mentioned today. Thanks!

Your alternator has a plug w/two wires. One of them should be a White/ Blue wire. Disconnect the plug and do a continuity test on this wire and the two wires that were connected to the EGI fuse and you'll see which one if either, by a process of elimination, is the one which runs to the alternator. Should take about 1 to 2 minutes of your time.

I got a little preoccupied today pulling out the interior and upholstery so I can look at every inch of wire. I've found so many connections that are just held together by electrical tape. I need to pull those all apart and solder them. I've also found several unattached ground wires after pulling up the upholstery and a few shorts in places like the storage compartment light bulbs.

I'll check the alternate before/after work tomorrow.

You need to make sure the wires that you perceive as grounds are definitely grounds before you have more electrical problems that you can stomach.

Well, these particular wires were wound around bolts in the frame and just wandered up behind the dash, only connected at the one end. That's partly why I'm pulling the dash out. I want to get this all fixed right instead of constantly worry about electrical fires or less dramatic failures. Not being able to drive my rocket is depressing, hehehe.

I checked the continuity to the alternator. I do have it on one of the two wires, but the colors are different. I've got what seems to be a solid yellow wire and a solid white wire. The continuity is on the yellow wire. If you are looking at the plug while it's in the alternator, the yellow wire is the lowest one.

I'm confused a bit. Which wire (wire color) at your engine fuse box is the one that you proved by doing the continuity test that goes to the alternator?

If you take a look at the last picture I posted of the wires from the plug, it's already been removed. The original owner left maybe a half inch of the original wire attached to the plug. There is a wire that might be the blue and white wire there, but the new wires he ran are all solid blue.

The only think I can say for certain is that I have continuity from the plug at the alternator to one of the two wires that ran into the egi fuse.

If we assume it was the blue and white wire, where would I go from there?

Where did you get that diagram from? I've got a haynes manual, which is nowhere near as readable as the diagram you posted.

As Hailers suggested, it could be the alternator causing this problem. So how about temporarily disconnecting the two wire plug to the alternator and place the proper sized fuse into the EGI slot (30 amps). Clean up the wire that is supposed to run from the EGI fuse to the Main Relay. Then start the car w/everything in place except for the disconnected plug and as it idles see what happens to the EGI fuse. Does it blow, does the single wire to it get hot and so on. W/the alternator disconnected the battery won't charge so don't idle the car longer than necessary.