I need to fix this when I go to try and get my car. it is 40 miles away on a mountain, miles from any auto parts store.

would a ground wire coming from my negative on battery to my e fan cause the main fuse to blow/melt if that wire had rubbed through the insulation and contacted the chassis? thats the only thing I see to cause a short. I looked all over but all the other wires seem ok, I didn't smell anything other then around the fuse box area.

long version:
so I started it up after work and it started and ran fine for a minute then it stalled. I cranked again but seemed like it was just spinning and getting no spark (tach needle not "bouncing" when cranking). so went to see if maybe it was super flooded (hoping) but the main fuse was melted along with most of its area in the fuse box. the nuts that the screws bolt into for the main fuse even fell out of the box since the plastic holding them was gone. now I found the 2 thicker wires on that fuse but I think I was reading that there is a third red wire hooked up there as well? I must have missed that one so correct me if I am wrong.

I'd like to fix this in one go as it takes a lot of gas to go back to a parts store. I'm going to grab 2 new main fuses (80amp I beleive but I have old one so will chack again) and fix that wire for my e fan and see if that works. if not I will be hunting. I have recently cleaned up my other ground points as well. less then 6 months ago.

 

Only if the coil in the fan was shorted as well. Otherwise ground wire can touch chassis no problem. The fan should be fused on its own with a smaller fuse anyway.

 

a ground wire is basically the whole car,so any ground touching the car will do nothing.

 

I would get a whole fuse box with new fuzes.

Actually....I would call AAA and get the thing back to my garage...but that's just me.

 

What you have is a short caused by a bare wire contacting anything metal (essentially grounding out). I had a FC do something similar, blew 2 main fuses before I found a bare wire (that didnt have a connector or an object to be connected to) touching the waterpump housing. Sealed the wire and taped it back against the harness, didnt have another problem afterward.

 

+1

Rotary > Pistons

 

Where are you sourcing power for the e-fan?

 

You want to make sure neither battery terminal comes in contact w/the underside of the hood as it will cause the electrical side of things to act rather wonky.

 

a charge post off the alternator running on an intercooler or other exposed metal could cause the box to melt down also. most of the boots that seal it from touching bare metal are nonexistent these days.

 

+1 for Satch, RotaryEvolution and RockLobster.

Given the situation, I wouldn't attempt a repair in the field and would absolutely get the car towed home, period. Unless you are skilled with electrical work and have a solid, almost subconscious understanding of the car's wiring and circuits, I believe it would create a larger problem.

The only way for a short to occur is if a Live 12v wire touches anything on or connected to the Ground Plane (Chassis). This includes the Engine & Transmission as the Battery's negative cable goes to the Main Chassis Ground (Driver's side front strut tower and then to the body of the Starter.. This article should help you gain a better understanding of how Grounds work: Proper RX-7 Grounding Procedures

Actually, I am rather surprised that the main fuse didn't blow almost instantly upon being shorted to ground. In all fairness/strangeness, I had something similar occur when the terminal for my alternator cable fell off of the cable, shorting on the UIM. This was in 2008 and caused by a faulty crimp/hammer-on terminal that failed while driving. All of the warning lights came on, several circuits such as the windshield wipers didn't work but strangely, it didn't blow any fuses or damage anything. Now all my cables are properly soldered and supported to prevent a recurrence.

One thing I do know is that if you mix up the Ignition-switched 12v and sensor wires when retrofitting a Taurus Alternator, it will instantly shoot up to its maximum power and peg the voltmeter at 15-16v. It took about a minute of this to blow the 100A main fuse I had at the time. But again, no damage to anything in the car.

As for your fan wiring, I am going to reiterate the questions above:
What fan are you using?
Where are you pulling power from for the fan?
How do you have your fan wired?

The correct manner to install an Electric Fan is here: How To Properly Install An Electric Fan

On my Project OldTree, I am using a 2-speed fan from a Ford Taurus, wired in the ignition-switched manner per Aaron Cake's article. As my battery is relocated to the rear, I have two bus bars under the hood, one for Constant 12v and one for Ground, in which all circuits are routed through and double as Jumpstart Points. From the 12v bus bar, power for the taurus fan is fed through a 50 Amp Maxi fuse (it's a thirsty beast!), then to the appropriate relay whose coil ground (Pin 86 in the diagrams) go to a 203 degree thermoswitch sourced from a 1974 Subaru GL, which threads right into the stock FC hole (M16x1.5). This thermoswitch also operates in the most common manner (supplies a ground at 203 degrees) instead of like the stock S4 one's reversed operation (removes the ground at 195 degrees). The Subaru switch also uses a common bullet connector too.

Due to the complexity of my circuit as it is a 2-speed setup with a total of 5 triggers, I keep a copy of the schematic on my android phone at all times. Same with my Haltech schematic.

My advice is to get the car home via AAA, disconnect the battery and start doing continuity tests. between the positive terminal and ground. If you see continuity, that means there is a short. Pull one fuse at a time untill you see the continuity vanish. You've just identified the offending circuit to which I presume your fan has piggybacked its power from. Based on lack of tachometer feedback, my gut feeling says it's either the EGI Comp fuse (30A), EGI INJ fuse (40A) or the BTN fuse (60A) as lack of power to the ECU or the coils would knock out the tachometer. IIRC, the 80A main fuse only affects the rear defroster, HVAC stuff & charging circuit, despite the alternator's output post being a straight, unfused line to the battery.

To accurately assess the damage and offer relevant advice on correcting this, we need to know ALL of the details of your fan install.

 

well, I went for it and just put in a new fuse after searching and searching visually for any signs of contact from wires and I found none anywhere. I didn't bring my multi meter with me but just went for it after searching. I have a 4 gauge wire going directly from the battery positive to the b+ on the alternator. this is an s4 na with stock alternator, 70amps.

the fan is hooked up to an ignition power source from a green plug that is unused near the battery area. it is fused and goes through an adjustable temp relay. I only have the fan hooked up to the low speed setting, it is a nissan quest/mercury villager fan.

I managed to hook up the new fuse and get it home with out issue. I only see 2 wires for that main fuse, the 2 that bolt to either end. it was a chore to get them bolted up as the nuts that were held in by the plastic fuse box were free and not being held since plastic is gone in that area. but its in. I'm thinking that this may have to do with my wire going directly from alt to batt. I have been searching circuits for a bit but whatever shorted is either no longer or I haven't found it yet. I need to check the ignition switch wires relevent to the main fuse in the bay. its odd that the car started, then stalled and blew the fuse with no movement of the vehicle and has run fine for about 2 months with the e fan in. I have stiff pbm coilovers and usually travel bumpy roads so I'm not surprised at this really. thanks for the help, sorry for late responses. I figured that a ground contacting chassis was nothing big.

 

what you should do is remove the fan power from ignition, use your ignition source to turn on 2 40a relays in parallel/1 80a relay to feed power to the fans directly from the battery.

i doubt it is your alt charge wire if it runs directly to the battery, it sounds like the ignition circuit is carrying excessive load and overheated. likely due to the fan running from power AFTER the 100a/80a fuse. that fuse carries power to the whole car and was not designed to carry such high loads with the fan wired into the ignition after it. i'm actually surprised it didn't burn up the ignition switch first though.

 

I agree with this advice but think the 80a relay is a bit overkill.
I've been running the much larger (and presumably, hungrier) Lincoln 18" fan for years on a 40a power delivery relay (hooked directly to the battery and triggered with the same green connector ign. signal as the OP) and a thirty amp fuse.

 

overkill is sometimes required. my black magic isn't supposed to pull over the rated 30 amps but they have melted several fuse blocks before popping the fuse, the result was still a dead fan while driving which is never a good thing.

so i always view any electrical fan requiring at least a 40a circuit at bare minimum.

 

I understand the "better safe than sorry" approach.

 

+1

I've completely melted that green connector and my main relay by running the fan directly off the green 6-pin. I was using a 30a Volvo fan... After connecting a 40a relay and a 40a breaker and a large gauge ground I didn't have any more issues.

 

What he said. Only, instead of fuses, use this: 40: Marine-Rated: Circuit Breakers | Waytek, Inc

I try to use manual reset breakers wherever possible. I've also had more 30+ amp fuses melt (along with most of the circuit) rather than blowing...

 

RotaryEvolution, Clokkar, allow me to state the obvious here for the OP's benefit:
CHASSIS IS GROUND

If you do a continuity test between the battery positive terminal and the original alternator output cable, you'll see that it's a straight line...weird. If I were to place a bet on a diagnosis, I would say that your original cable shorted out. This is exactly why I took the time to extract all of the power & ground cables from the Engine Harness, replace the battery/starter/alternator cables with 4awg welding cable and remove the redundant original alternator cable. All it took was cutting it off where it merges into the cable between battery and fuse box. Crimp on a ring terminal to the fuse box cable and put it on the positive terminal along with the 4awg Starter and Alternator cables.

My car has had a 4awg cable between the alternator & battery for 5 years now and it's not melted anything

The Villager/Quest fan is essentially the same as a Taurus Fan, give or take a couple details. The reason your fuse box melted is because you piggybacked an additional high current load on a circuit meant to carry a certain load. This is 110% wrong.

Here is the correct way, guaranteed to not melt/damage anything

At the 40A relay
Pin 85: Ignition-switched 12v+ (the green connector)
Pin 86: Fan thermoswitch
Pin 30: Battery, via a suitable 30-50A fuse
Pin 87: Fan's 12v+ wire (Low speed for your configuration)

Fan's ground wire goes directly to chassis. IIRC, Ford used 8 gauge for all 3 wires, so you need to do the same. If it's in good shape, reusing the stock alternator output cable here is a dirt cheap way of tackling this correctly. If used for powering the fan, be sure to tag it appropriately in red to avoid confusion.

As for understanding how grounds work, here is your answer:
Proper RX-7 Grounding Procedures

Engineering overkill in an electrical circuit is a GOOD thing. Electrically speaking, my car is done as such with a group 48 battery & taurus alternator. The result is that it will crank and start no matter what.

 

I understand everything now. I must have misunderstood the e fan threads as I have a relay but am pulling power from that green 6 pin plug. Thank you everyone, I will wire it correctly and that should be the problem it seems. I will make it a priority to swap my battery/starter/alt wiring too as it is old and corroded (hance the extra b+ to batt wire). Been meaning too but need to get on it.

 

There ya go..your mistake.
You can't pull 30 amps from that Connector.
You can supply the relay to the Fan to get switched power but you can't supply power to the fan from that Connector.You need to put the Fan power to Battery.
That was your Mistake right there.

 

I never said I didn't make a mistake. I didn't realize I wired it up wrong either though. I'm not great with wiring and relays, I was trying to understand the e fan threads here to get it hooked up properly. thanks for the help everyone.

 

Internet doesn't express so well.
Just saying that "there ya go..heh..ya found it!"
But at the same time I was pointing out that the Wiring can't hold 30 amps and something was bound to cook!..
It's a simple over look,and it's been done before.