Nevermind page 50-13, it apparently doesn't exist. I should have said 50-14. I assumed they were numbered in order .

The circled 3 lets you quickly track down what components the Y/R wire powers. Any time you see a circled 3 on the "B" 12V line, it will be the Y/R wire from the front harness. Note that there are two other wires with a circled 3, but they receive power when the ignition switch is rotated (denoted as start (S), accessary (A), then ignition 1 and 2). "B" is battery power & is constant.

Going through the FSM, I found these pages that show the Y/R(F) wire running to components:

50-22, Y/R(F) wire running to ECU pin 3J through FEM-01 & FEM-02 (pg. 50-14).

50-70, Y/R(F) wire running to FI-01 (becomes Y/R(I)), then the warning lights / clock.

50-74, Y/R(F) wire running to various lights, ing. switch key reminider/CPU.

50-94, Y/R(F) wire running to theft deterrent system.

50-96, Y/R(F) wire running to radio.

50-104, Y/R(F) wire running to ABS unit (if applicable)

Surprisingly, the ROOM fuse allows power to one pin on the ECU, as well as lighting, etc... Also, if you haven't noticed yet, each of the connectors are named for the two harnesses they join together. For instance, Front harness to EMissions harness connectors are called "FEM-xx". FEM-01 & FEM-02 are tucked up near where the EM harness comes through the firewall to connect to the ECU. FI-01 is the connection between the front harness and the instrument harness, so it's going to be somwhere behind the dash; maybe behind the cluster.

 

Congratulatoins! You guys have found the ONLY BW wire on a SERIES FOUR car that is a ground. The Engine half of the plug goes to the shield on the CAS plug. The BW in the Front side of that plug goes........heck, I don't know (probably the gnd block under the trail coil assy that's bolted to the aft side of the strut tower..guessing).

I removed both batt cables. The BW wire in the Front side of the connector measures 0.4 ohms, almost certainly going to a solid gnd. Then measured the BW in the Engine side of the plug and ohm'd it to the shield on the CAS plug. Confirmed 0.2 ohms. So that BW is not a mystery anymore.

I have half *** read this thread, and noticed in one post where someone said when he mated the FE-02, that the BW mates with NOTHING. That has meaning to me. There's another six socket plug in that area. It has a BLANK (moisture plug) in the top row where if one MISMATED the plugs, you would have a situation where the BW mates with *nothing*.

So I suggest when mating the six socket plug halves, that you pay attention to the wire colors in one half and see if the colors in the other half are the same color (that does not happen in all plug mating, but in most plug mating).

The series five cars a fugged up in that they use several BW wires for Grounds. Dumb.

Seems some of ya'll are in the USAF. Using terms like glare shield and several other airy terms.

 

So what do we win? Hopefully your input on what the heck is blowing his room fuse.

 

haha, was in the navy. now im a contract helicopter mechanic for the navys test pilot school in MD. hell of a guess though Hailers! lol, thats awesome. ok, to sum it up for you, that B/W wire from the plug was origionally connected to the shielding of the CAS. so i should just bolt that to a solid ground? as far as the one with the moisture cap, thats all straightened out. but like rotrkt88 said, we're all stumped as to why the room fuse keeps blowing up on me on contact. id really like to trace the L/R wire from the interior fuse box to see where that goes, but theres about 3 miles of wire all coiled up back there, so when i start to follow it, it just disappears in the rats nest. lol please help! thanks. Brian

 

I second that motion! and thanks for pointing that out to me in the diagrams man! its funny, cuz it says all that right next to the connectors but i always read over that and never took notice! lol learnin good sh*t everyday on here!

 

Well, i am now 100% convinced that the problem is in the interior somewhere. i unwrapped all that i could in the eng bay, and that W/R wire, and all other wires for that matter, are lookin good. im still having a hell of a time tracing the Blue/Red wire that leaves the room fuse to follow where that goes. i have it labeled in 2 areas, but after that, i cant see anything. we need to call in all experts in that area. thanks!

 

The CAS plug at the cas has a shield wire sticking out a bit from the harness. At the other end of that harness is the FE-02 that has a B/W wire. That is the same wire as the shield. It should mate with the other half of the plug and the B/W should be mating with another B/W wire.

YOU said somewhere above that there is no B/W wire in the other half of the plug. Is what I wrote true?

Is this a 1987 turbo car? Not some na to turbo car but the real deal???? What year is stamped on the plate in the drivers side door jam? Like June 1987 as an example. And NEVER been a Automatic made into a manual type car either. Some plugs are diffent on automatics.

What I did was go out to my stock 1987 Turbo car and remove the trail coil assy so I could poke around. This is an early 1987 with the solenoid resistor etc.

Anyway, I noticed that the FRONT harness comes out of the interior there. The large trunk harness. Now on the FRONT side of the harness are two six socket plugs near each other. One plug on the Front harness side is male and the other female. Those mate with their respective halves on the ENGINE harness. One male, the other female.

So. I was wondering if somehow you connected the two six socket plugs on the FRONT harness together? instead of connecting them to the half of the plugs on the ENGINE side of the harness???????

By the way, when in your other post you said there was no B/W wire in the other half of the plug for the B/w wire to mate with...that is what gave me the idea that your mating the wrong half of plugs together. Because on my early, stock 1987 Turbo car, there is a B/W in both halves of the plugs.

But the other six socket plug has one socket where there is nothing at all. Just a moisture plug/blank.

If your real sure that your mating the right halves of the plugs together, then I'll try to take more of an interest. Just don't wanna waste your time.

It's normal for the elec fan to come on if the EGI fuse is pulled and or the green/black wire is pulled off the fan temp switch on the thermostat housing. Doing either relaxes a relay in the ENGINE FAIL unit which in turn causes the fan to come on.

 

You done did win tha BOOBY prize. Call your local dating service and tell her I said to give you a FREEBIE!

 

Here's a sample. There are other pages that have 9..3 on them also. It won't take but a minute to page thru the wiring diagrams and stare at the B line til you see the 9...3 numbers as shown in the attached jpgs. EAch 9...3 will have a L/R wire under it going to something or other.

 

I was reading some of the early posts and there was a question about pwr on the interior fuse box. I attach a jpg of the box cover and wiring diagrams.

Key out of the ignition only the upper fuse rows have power. That's the BATT bus.

Ig1 and IG2 fuse rows are fed power from the ignition switch itself and only if the key is to ON or better. IG2 loses pwr when you go to Start, but pwr comes back on when the key is returned to ON.

Kinda sorta like an airplane circuit breaker panel. Got your non essential bus, essential bus, emer bus and batt busses and not all powered at just any given time

 

Thanks for the help Hialers! That makes more sense to me now. And yes, earlier when i first started chasing this issue, i made a bunch of mistakes (mostly overlooking) in the mating aspect. im now positive the engine bay is good to go. for ***** and giggles, i cut the L/R wire about 4 inches away from the fuse box, low and behold, the fuse didnt blow on me. thats why i am dead set on following that wire EVERYWHERE it goes, cuz once theres power to that wire, FRIED!

 

Well a lot of people pick power off that wire for a radio. NOT a good idea at all. SO maybe go to any audio device and unplug it and see what happens.

Origianlly you seemed to have had a METER fuse blowing when you went into fifth gear. Now its the room fuse blowing. So (I assume two different problem.

As mentioned earlier the room fuse feeds a wire on the small plug of the ECU (MEMORY power I think). So pull that plug off. Not likely it's that plug though if this is stock Mazda Turbo wiring. IF it were a turbo swap of any sort it might be other stuff.

One of the diagrams show it feeding all sorts of door switches etc. Pain in the *** things. Like seatbelt light etc.

Some cars have lighting in the stowage compartments. Someone on this forum had the room fuse blow because one of the cubby hole wires was shorted.

 

well, heres sort of a good news/bad news post. in the fuse box and ignition area, found 3 separate L/R wires. One is for the interior lights, one plugs into a small connector under the steering column, and the other is the one i hacked to find out that its definitely the wire shorting out. The good news is that the wire from the fuse box is a thicker gauge than the other 2, and that i THINK it joins the huge *** bundle that goes to the other side of the car. the other part of the good news is that its also the same gauge wire as the one going into the ECU. I ruled out the radio and cuppy hole wiring because when i did the stereo, all of that wiring was removed (not cut, just removed from the plugs). also some bad news is that im not 100% sure that the wire from the fuse box is the same as the ECU memory wire, but it sure looks like it may be. I ran outta daylight, so this is as far as i got. a plan i am seriously considering is cutting the L/R wire at the ecu, running a test wire, and joining that with the section i snipped at the fuse box, however, i dont wanna try it unless someone tells me that it is a bad bad bad idea. The fact is that its definitely the root of this problem, but i STILL cant find out that wires next stop from the fuse box. Then we can go from there. Sound good?

 

darn, no one has any ideas? luckily weve been getting a lot of rain, preventin me from goin outside and working on this thing further. or i prolly would been hackin into more **** by now. haha. for now, just been trying to locate the next stop in that Blue/Red wire coming out the fuse box, but have had no luck at all.

 

The next stop in the L/R wire's path is likely going to be the warning lights, then on down to either the alarm control unit or the ECU. The alarm control unit is behind/underneath the glovebox, so you can access that area by removing it. It's actually very helpful when working in that area to have the glovebox removed. The exact path is a mystery, unless you want to take apart the dash, but you can stick to the components you know get powered (like ECU pin 3J) and figure it out.

 

yea, that sounds good. but the wierd thing is that when this first happened, and the fuse was blown, the warning lights still worked. since then, i been gutting the interior, seats, ect to get more access to things. pulled the ecu and all, then hit a stopping point due to all the rain. ima start going through things one at a time again, starting with re-connecting the Blue/Red wire at the fusebox. Hopefully good things wil start happening.

 

in the past few days, all i have figured out is that the L/R wire thats shorted turns into a W/L wire somewhere down the line before it gets to the ECU. just dont know where. pulled the glovebox and radio today, im just going to pull out the entire dash, hoping that will expose all wiring harnesses and bundles. then i can just start testing continuity between everything. hopefully it will narrow down the shorted area, then i may be able to determine the cause as to WHY it was shorting out. either way, ill let ya'll know what i come up with.

 

ISSUE SOLVED!!!! It was the wiring to the ignition cylinder key light! bulb wasnt burnt, but the wiring about 2 inches before it (2 red wires) were fused together, causing constant contact between the L/R wire and the G/W wire. tomorrow morning im going to connect everything back up, with the dash still out, and do a quick test of the lights. But for now, its starting to look like things are back to how they should be.

 

That useless little light was causing all this trouble? Nice catch. Hopefully when you get it all back together, your fuses all stop blowing. *crosses fingers*

 

Wow, that is a crazy problem! Good catch Keep us updated!

 

tested it today. let the lights on for about 10 minutes, then started checking wires to make sure nothing was getting hot. everything checked great. got the dash, radio, tv, heater control, and all heater tubes ducts done this morning before work. all thats really left is the interior neon, a few kick panels, and door panels and the insides all done. just gotta clean up the engine harness under the hood and get that all straightened out. but im sure ill run into a wire that i dont know where it goes. haha, so ill definitely be back soon. i really appreciate everyones time helpin me out through this problem. ya'll f'n rock!