XxMaCaBrExX

Ok, I've asked you guys for help finding a fuse diagram for my rex before as I bought it without a fusebox cover, and I did get a few from you here and there, but I have since figured out that they are all slightly different. I have a '90 GXL model ( I'm pretty sure it's a GXL at least ) , and I'm having electrical issues. One of the fuses blows everytime, and I need to know what that particular fuse goes to before I can find the short. PLEASE HELP ME!!! Ok, I feel better now.

Thanks,
XxMaCaBrExX

HuggyBear

iv got a 90 gxl.

email me at firebat@mts.net and let me know exactly what you need and ill try and hook you up as best i can.

XxMaCaBrExX

YGM

XxMaCaBrExX

Anybody else??? :p

Sniper_X

Go to home depot and buy one of the most useful tools in the world and solve the problem at the source.

Get a signal generator and a volt meter (with resistance and continuity).

remove the battery.

using the continuity setting of the meter, see which side of the fuse is going to ground.

clip the signal generator to this side of the fuse connection.
use the signal "finder" and listen to the tone that is emitted and follow the wire(s).

Find where the signal dissappears (or reduces to almost nothing)in the wire/ device.

(My guess is that its a lighting / instrument cluster/ or radio-lighter fuse.)

The short is near the place you lost signal.

this will also tell you which accessory it is.

XxMaCaBrExX

Well, I'm pretty sure it's the Instrument cluster fuse, as that doesn't seem to be working now. I have pin-pointed a nasty looking wire that has the insulation melted all over it. It runs out the top of the fusebox and into the FOREST OF WIRES! I tried clipping away the tape that held all of the wires in groups, and I following the wire all the way up until it didn't look melted anymore. I clipped it at that spot, and near the end connected to the fusebox, then replaced the wire in between. Apparently, theres another bad spot somewhere up in the dash where I can't reach, because it still blows the fuse. Just for reference, it's the black wire with a yellow stripe, just incase any of you are electrical geniuses on 2nd gens. I've already got a volt meter, but I'll have to go get myself a signal generator. Does anybody know if the buzzer/dinger thingy under the dash is on the same fuse as the instrument cluster, because when I put a fresh fuse in and turn the key, the buzzer/dinger makes noise for an instant before the fuse blows.

Sniper_X

im sorry to hear this.

At this point, you simply have a massive failure in SEVERAL pints in the wiring harness.

You see when that wire melted it melted the neighboring wires too.
the all (under the pressure if the harness being wrapped) joined together and since then that section is toast.

I reccomend that you NOT put the battery cable back on until you rip down the side of the harness and replace the wires affected, using solder to join the defect wires to new ones, making sure that you use shrink tubing to cover the splices.

then re-wrap the harness.

I have had to do this once before and i will tell you this.

You should remove EVERYTHING that can come out from under the dash. (aside from switches and the like.

Prepare the work area as if you were removing the harness inside the car for replacement.

If you will help me identify the parts effected with pictures, I will break out the wire harness assebly diagrams and tell you where the next disconnect for the effected circuits are.
you could remove these and attempt to cut them out summarilly.

You have a big job on your hands. but once its complete, you will be very happy you did it the way you did.

And in the process, you will gain a skill that is considered a black art my most everyone.

HAILERS

Did I hear someone say BLACK WITH A YELLOW STRIPE? Did I hear INSTRUMENT CLUSTER? Why did not you say something. The insturment cluster has two round connectors. The one you are interested in is the outboard one. Pull the plugs off the insturment cluster and get your meter and ring from the black and yellow wire in the outboard round plug to the bare wire you've been messing with. That the wire? Well that circuit goes from the key switch, to the 7.5 amp fuse, to the C03 connector between front harness and meter harness, to the round connector on the combination meter called C01(the outboard of the two round harness plugs) to the guts of the combination meter. You can play all sorts of games now. Leave the round C-01 off and with the fuse in turn the key on. Pop the fuse or not? Oh, did you ask where the C-03 connector is? Well its a 21 pin connector, rectangular in shape, under the dash. You should be able to follow the harness from the meter to it. Both round connectors on the meter go to it. Write back if that is the wire. I'd find the C-03 for you but I loath under the dash work. Let me put that another way. I LOATHE UNDER THE DASH WORK. Oh. The round plugs. To disconnect them, there is in the center of them a stalk that you have to push towards the center or perhaps outboard for the plugs to come off. They do not pull straight off until you do that.

XxMaCaBrExX

Yes, I've had the entire intrument cluster completely out for the past week. I only just found the melter wire yesterday. The fuse still goes bye bye with the cluster unplugged. I can see the C03 connector, but it's going to be a mean one. It's right out of reach behind the airconditioning tube, so I'll have to use some chopsticks or some really long needle-nose pliers to get back there. So that wire starts out at the key switch huh? Well this car was broken into before I bought it and they tried to hotwire it. Could that have something to do with it? I'll investigate further with my trusty voltmeter and reply some of my findings whether fail or success. Thanks for all your help, this is making things alot more educational for me.

HAILERS

Well, better late than never. Forgot to tell you my diagram is a 87. It shows the 12v from the battery to the 80amp fuse under the hood to the ignition, to the 7.5amp fuse that must be the one you are blowing, to the rectangular C-03 connector, to the C-01 round connector at the combination meter. Since it blows with the combination meter disconnected, you'd have to think that the 90 model must have something else spliced into it after the fuse. If you've ohm'd the wire from the C-01(the combination meter) to the fuse holder, then you must be on the right wire. Of course you could ohm the wire to ground and see if it is grounded (must be you're blowing fuses). Its really hard to believe a connector that we cannot even touch is the culprit, but your going to have to look at it anyway. Almost too hard to believe that its the ignition sw since its on the other side of the fuse. Has to be on the side of the fuse that goes to C01 at the meter. I wonder if you have some kinda theft device that someone put on the car or if someone has added a loud **** noise device (music) as an after market. Just rambling, like you said you'll let us know what happens. Gotta get back to roofing the garage before it rains.

XxMaCaBrExX

Okay, update. I tested from one end of the black/yellow wire at the fusebox's end (without it even being connected all the way to the fusebox) up to the black/yellow wire at the C03 connector... NOTHING! I hjad previously noticed that there was a second black/yellow wire that came from the fusebox and eventually spliced into the original black/yellow on the way to the C03. Both black/yellow wires are now cut before they go up to the C03, but they're still spliced together. I hooked the battery back up, popped in my send-tolast 7.5A fuse, and PLOP! Out goes the fuse. Wouldn't this mean that there's something fuxored in the fusebox itself? I've thoroughly inspected all other wired originating from the fusebox, and the two black/yellow's are the only melted ones. I tried to take the entire fusebox out of the dash by removing the nut at the bottom, then unplugging the three connectors on the side, but it's still in there pretty good. Is it even poissible to remove the fusebox without cutting all of my wires? Oh, you mentioned a sound device. There was a stereo system (aftermarket) installed, but the same thieves who tried to hotwire it stole that, too. Could that be the culprit somewhere? AAAHHHHHHHH!!!!!!!

HAILERS

So you still have one fuse left, eh? Lets fry it. I noticed that in section M, Theft Deterrent System, there is a black with yellow stripe that goes to seemingly the same fuse. It goes across the car to the passenger side to something called the Contro Unit for the theft system. No stops inbetween. The plug is a 17 pin rectangular connecter. The not so graphic picture shows the unit would have been mounted to the left and above the speaker on that side. Did your car have a theft device? Anyway, if it were my car, and I had a pair of dykes in my hand, I would place the wire that goes to the passenger side of the car inbetween the two halves of the dykes and press home leaving enough wire to splice the darn thing back together if needed. First you should try to find the plug that is supposed to go to the theft control unit, 17pin connector.. I never took a fuse box out. I'm betting that it is ok. But your there and I'm here. I did not fully comprehend what you said about the wire being cut. We're pretty darn sure its not the combination meter so it has to be the other end of the spliced in black wire with a yellow stripe. Pull the fuse. Turn the key on. On one side of the fuse receptacle you have 12v. On the other side see if it is going to ground. If it is don't put the fuse in until you rid yourseld of the ground on the wire. But you know that with only one fuse left, and they made no more. You've got the last one on earth. Back to roofing the garage. Been in the sun too much today and its showing.

XxMaCaBrExX

Ok, let me try to explain better. The first black/yellow wire that I noticed was fried also had grey bands. Then, I also noticed the next black/yellow wire which had red bands. They are both originating at the fusebox. After cutting the tape off of the mass of wires, I followed them both about 7 or 8 inches up towards the C03 connector, and found that they were spliced with a "Pinch" wire connector and then continued on as a black/yellow with no bands which seems to be fine with no melting and such. Right now they are both cut about 2 inches from the fusebox, and at the point where the were spliced. The ends still connected to the fuse box appear to be toasted all the back to the back of the fusebox where I can't see or reach without removing it. At this state, I cannot get a signal from the black/yellow with no bands to the C03 connector up in the top of the dash behind the cluster. I can however get a signal from the C03 connector to the round plug at the back of the cluster. The fuse also still blows even with both black/yellow's that are coming out of the fusebox are connected to nothing. Now I can get a signal from one connector pin in the fusebox (the slot that keeps blowing the fuse) to the black/yelow with red bands. I am guessing that there is a mass of melted wires behind the fusebox ( which I can't remove for the life of me), and possibly some meltage between one end of the black/yellow with no bands and the C03 connector. Any ideas?

Icemark

First pull and remove the non-factory scotch (or Botch) lock joining the two wires... that shouldn't be there and suggests that someone has been hacking up your wiring.

Two... seems apparent to me that you need to pull the interior fuse box down. As I recall it was only two 10mm bolts, but I will have to go look when I get home tonight. either way it sounds like you need to get to all the wires coming from the box, and if you have cut the wire and it is still blowing the fuse, you have another wire coming off that fuse going somewhere else.

BTW: the dashs tell you what harness that wire is in, as I recall red/brown dashs were the engine harness, and silver dashs the front interior harness... but again I'll check for you when I get home tonight.

XxMaCaBrExX

The wire connector was factory I believe. It wasn't the plastic covered kind, but more of a small metal peice folded over the wires and clamped together. I only see one nut on the fusebox, and I've already taken it off. It's just that there's so many wires connected to it, that I can hardly move it at all, let alone turn it around to the back to see what the problem is. It seems that I'd have to cut all the wires off just to get it out of there. Am I missing something here?

HAILERS

Until the Icemark gets back to you, have you considered downloading the factory manual for 88 model that is free at the http://www.iluvmyrx7.com You could just download the electrical portion that has the wiring diagrams. Best viewed is you print it out. And I looked at the manual and the red stripe indicates the front harness. It does seen to be one real bad problem you have. I still think the other black with yellow goes to the theft system on the right hand side, but if the wires are seperated from the fuse box thats not the problem. Sorry can't help anymore. Maybe I'll take a look at my fuse box tomorrow to see what it takes to remove it. Not real keen on doing that. By the way, I doubt the 88 manual is much different than your car. And a dig at Mazda...the 87 manual is superior in every way, especially the wiring diagrams.

XxMaCaBrExX

Well, I'm pretty confident that my problems lie in the fusebox itslef, and somewhere in the jungle of wires between the fusebox and the C03 connector. My only hope now is to get the fusebox out without cutting all of the wires, and then ripping all of the factory electrical tape off of every wire in the car. If anybody does figure out the secret to removing the fusebox, please don't hesitate to fill me in.

Icemark

Okay looking through the fusebox you have two Blk/Yel wires, one for the convert roof (which you wouldn't have) and one that splits off of the fuse box to 9 other things.

To confirm that its not one of those nine things you will need to unplug each one, one at a time and check to see if that is the problem. If they are still blowing then it is in the harness and your best bet is to replace the harness.

here is the layout:

The four wires going off at the bottom are large gauge wires (blu- accessory, Black- 12v+, Blk/wht (which powers the fuse in question) Ignition 1, and Blk/Red - ignition 2).

hope this helps.

XxMaCaBrExX

Is there anyway I can get a little bit more of that layout pic. I was following a couple of wires and they disappeared off the screen.

XxMaCaBrExX

Update:
Okay, I've gotten the fusebox off. Just for reference, after you take off the three connector plugs attached to the left side of the fusebox, you can then un-clip either side of the holder that the fusebox is connected to. I've traced the red banded black and yellow wire back to the "Meter" fuse. I then traced the silver banded black and yellow wire to the top of the fusebox. It's not connected to any of the fuses, but there are about two or three other wires that are identical to it coming from the same place on the back of the box. The "Meter" wire tests just fine to the "Meter" fuse slot, but I tried testing the other one to all of the fuse slots and got no signal. I then accidentally bumped the inside of the car (bare metal) while the tester was still connected to the black/yellow w/ silver wire and got a signal. Apparently, the wire is somehow grounded to the body of the car. Now what I'm trying to figure out is what the hell that wire is in the first place, and why the HELL it was spliced to the meter fuse wire. Just a quick question, if the meter fuse is out, then isn't the CPU not netting any juice, and wouldn't that cause the engine to run like ****? Any further ideas from you guys?

Icemark

Nope that wire goes to the CPU (Central Processing Unit- read body computer) not the ECU (Engine Control Unit). Two different 'puters.

As I said in the ealier post to trouble shoot the problem:

To confirm that its not one of those nine things you will need to unplug each one, one at a time and check to see if that is the problem. If they are still blowing then it is in the harness and your best bet is to replace the harness.

XxMaCaBrExX

Okay. After removing the white plastic cover at the top of the fusebox, I now see that apperently, all of the silver banded black/yellows are connected (there are 3 of them total). I also pinpointed that one of them is grounded to the body somewhere, which in-turn, grounded all of them (including the one running to the ECU.) I just have to follow it and find out either where it's supposed to go so I can replace it entirely, or where it's grounding at so I can replace just the bad area. This will take some time either way, as it happened to run into the largest bundle of wires and disappear. I did notice that it was bundled with the Voilet and the Black/Red wires just incase thats a clue to anybody. Now one of those black/yellows that I mentioned was running to the ECU (The ECU is the one with the Mitsubishi sticker on it , right?) Now if this isn't working properly, whether it be fuse, or short, or what have you, will my engine run, or run like crap if at all?

HAILERS

I've had the middle ECU plug off a 87 while wiring a breakout devivce to it, gone off to do a chore,returned to drive off somewhere and the thing started alright but you knew you were not going out of the driveway. Ran real rough. Can't say how far I could have gone. All during your post since we found out one of the wires goes to the ECU, I've been wondering if your car ran at all. My 87 manual shows a black and yellow going to two of the plugs and I got the impression from Icemark that only one wire went to the ECU on your model. I think your ECU is a different configuration. Mine has three plugs where Maybe yours has one. Never seen one. My 87's black and yellow do not match exactly where your black and yellow go. No help here.

Icemark

Again...

THERE IS NO WIRE COMING FROM THE INTERIOR FUSE BOX THAT GOES TO THE ECU....

THE INTERIOR FUSE BOX WIRE GOES TO THE CPU.

two different buggers/computers/controllers/PCB/etc.

The CPU controls the body electronics. THE ECU CONTROLS THE ENGINE.

I am sorry I have not been more clear, to check the wire UNPLUG THE COMPONENT, such as the CPU or the Air Cond/blower. Then you can check for ground. but if you are checking with the component plugged in, you will see the ground plane of the component. If your test device does not see ground with the unit UNPLUGGED then you don't have a short in the wiring.

ONLY IF THE WIRE SHOWS GROUND WHILE THE COMPONENT IS UNPLUGGED CAN YOU TEST THAT.

If there is no short to ground you need to try plugging each component back in one at a time. The component that blows the fuse is bad and needs replacing or fixing.

XxMaCaBrExX

Okay. The troubled wire is going out through the firewall. Now all I need to know is what the black/yellow wire that goes out through the firewall is, and what it is connected to. The other two black/yellows stay inside the car, and I have found the short in that one remaining wire. I guess it's either the wire is melted to the body (or another wire) somewhere, or whatever is at the other end of that wire is shorted out.