I think I must be crazy... August 10, 2007, 09:58:29 PM ...crazy to tear apart a perfectly good wiring harness simply because I don't like the way Ford did it. We all know that the way Ford wired these cars is really, really stupid. They wired them so that all of the headlight (and foglight, in cars so equipped) current passes through the headlight switch instead of using relays - this results in premature headlight switch failure. I'd already taken care of that problem when I rewired the headlight system (I made a post about it months ago).Even worse, though, Ford wired these cars so that certain parts of the ignition switch carry very high current to feed several accessories that really should be relay driven. This results in the famous "flammable Ford" ignition switch failures and fires. The worst offender is the main "run" circuit, the grey wire with yellow stripe coming out of the ignition switch. That wire feeds the signal lights, heater, cruise control, O2 sensor heaters, electronic cluster, charge circuit on the alternator (via the AMP light in the dash), rear window defrost relay, and in heavily optioned cars it also feeds other circuits. That is why when an ignition switch fails the car will usually run but the signal lights, gauge cluster, and heater all stop working (if the car doesn't burn, that is). All of those circuits are simply too much for the contacts inside the switch, so they burn up.Long ago I decided I did not like that setup, so I installed a 75-amp relay sourced from an Impala cop car to carry the load. This worked very well, but it was crude, and along with that relay I also had a remote starter, fog lights, and power lumbar seats installed. This added a bunch of extra wiring, along with four "inline" fuse holders.Now, with the dash out, I've decided to wire the car the way it should have been wired to begin with. This is a simplified diagram of how Ford wired the car (other circuits in the ignition switch have been omitted for simplicity's sake):As you can see, the single contact inside the switch feeds a LOT of current. The heater alone would be enough to overload a set of contacts. When I had installed the 75 amp relay I simply cut the grey/yellow wire coming out of the switch and made a relay complete the circuit, so the ignition switch was only carrying enough current to turn the relay on (about 250 mA).As stated, this worked OK, but I discovered a slight problem: The remote starter was still carrying the full brunt, which caused it to frequently blow fuses (if I remote started it with the fan on anything other than LO), and yesterday I even discovered some charring on the wires. Time to completely redo the whole setup. Now the ignition switch will be carrying the current of the O2 heaters, AMP light feed, and turn signals. The heater will have its own relay, and the cruise/cluster/rear defrost/etc will have its own relay. I've used a minifuse holder from an old cop car to hold the fuses for the remote starter, fog lights, lumbar, and even the heater and cruise/cluster/etc relay coils, which will seriously clean up under the dash. The main ignition circuit is now wired as follows:The two 30 amp and the one 20 amp fuse in the "aux fuse panel" are hot at all times, the two four-amp fuses (and the one empty spot) are hot in "run". The factory accessories (heater, turn signals, etc) will retain their factory fuses, only being fed differently (through the relays).Now, if you're still with me, this leads me to the "I must be crazy" part: Even with that dash out, the wiring at the back of the factory fuse panel is a BITCH to get at, and get at it I must to repin it. Great fun... Quote Selected
I think I must be crazy... Reply #1 – August 10, 2007, 10:16:20 PM What software do you use to make these diagrams? Quote Selected
I think I must be crazy... Reply #3 – August 10, 2007, 11:50:43 PM that looks great man:bowdown: ever seen the contacts of a relay feeding another fuse and when energized, this fuse is inline with the coil of another relay?the first relay contacts were fused at 30 amp, the the second fuse which was inline with the second relay coil was 40 amp!!!!confussed the outta me but thats Mack for you , Mack is relay HAPPY ill tell ya. looked more like a bandaid circuit for a problem and they decided to over rate it with 70amp.im only good up to three relays in a circuit before i start pulling my hair out!!!!!!!:mad: It starts reminding me of cells splitting 1-2-4-8-16 and so on., to many directions to go.the only downside to relays is you double your fuse requirements and your panel will quickly grwo and have redundant fuses perse'. Wonder if they make a relay that has an onboard fuse holder? I think this is why a lot of car makers decided back then to use fuse links,, and we know how reliable they are! Quote Selected
I think I must be crazy... Reply #4 – August 11, 2007, 12:11:26 AM Carm thats some fine mspainting if I do say so myself. Quote Selected
I think I must be crazy... Reply #5 – August 11, 2007, 12:22:10 AM no shiznit,, and he even outlined the arrows. i gotta figure out how to do that. MS paint is so much quicker for me almost all the time. Quote Selected
I think I must be crazy... Reply #6 – August 11, 2007, 12:25:56 AM I'm partial to Visio. Quote Selected
I think I must be crazy... Reply #7 – August 11, 2007, 04:47:33 PM I'm going to have to learn how to use that MS Paint. That's real nifty. Quote Selected
I think I must be crazy... Reply #8 – August 11, 2007, 05:20:53 PM Big job, but if you want it done right, you gotta do wutch ya gotta do. Killer job with MS paint...I'd probably never be able to do that! Quote Selected
I think I must be crazy... Reply #9 – August 12, 2007, 08:57:44 AM Arc suppressing diodes should be used across the coils of relays when they are deenergized by opening a switch or another relays' contacts.The diode provides a circuit path for the current induced by the collapsing magnetic field of the relay coil.Without the diode, excessive arcing will shorten the life span of the switch or relay that opens the circuit.Some relays are made with this diode built into the assembly. It will have a polarity requirement for wireing the coil. Quote Selected
I think I must be crazy... Reply #10 – August 12, 2007, 09:13:22 AM Damm you did that with ms paint ! nice work Quote Selected
I think I must be crazy... Reply #11 – August 12, 2007, 10:04:55 AM Quote from: jcassity;167863that looks great man:bowdown: ever seen the contacts of a relay feeding another fuse and when energized, this fuse is inline with the coil of another relay?the first relay contacts were fused at 30 amp, the the second fuse which was inline with the second relay coil was 40 amp!!!!confussed the outta me but thats Mack for you , Mack is relay HAPPY ill tell ya. looked more like a bandaid circuit for a problem and they decided to over rate it with 70amp.im only good up to three relays in a circuit before i start pulling my hair out!!!!!!!:mad: It starts reminding me of cells splitting 1-2-4-8-16 and so on., to many directions to go.the only downside to relays is you double your fuse requirements and your panel will quickly grwo and have redundant fuses perse'. Wonder if they make a relay that has an onboard fuse holder? I think this is why a lot of car makers decided back then to use fuse links,, and we know how reliable they are!If building cop cars has taught me anything, it's taught me that there is no such thing as too many fuses. Every branch of every circuit should be protected by a fuse small enough to cover the smallest wire in the circuit. In my circuit the large yellow "input" wire is protected by the factory fusible link, while all of the smaller branch circuits have their own fuses.Quote from: jcassity;167873no shiznit,, and he even outlined the arrows. i gotta figure out how to do that. MS paint is so much quicker for me almost all the time.I've been using MS Paint since 1987 or so, back when it was a DOS program called "ZSoft Paintbrush" bundled with a Microsoft mouse driver floppy, and I had to save the files in the PCX file format. I've gotten quite used to it. Every image I make, including the animated GIF in my sig, is made using MS paint. In the case of the GIF I make each frame using MS paint, then put the frames into an animation using another very old program: Animagic32 (I occasionally use Jasc Animation Shop Pro, too). The other imaging software I use is Jasc Paint Shop Pro. I generally only use that one for resizing images or converting file types (such as converting the wiring diagrams in this thread from BMP to GIF).I've never, ever used Photoshop. Too fancy and complicated for me......Oh, and about the outlined arrows: I did that because the wire colours shown are accurate. For example, the two wires coming off the 20 amp factory fuse are blue with a pink stripe. The wires were drawn line by line - first a blue line, then a pink line next to it, then another blue line. The arrow heads themselves were drawn by making the outline shape of the arrow in the "base" colour for the wire (in this case, blue), then filling it in with the "stripe" colour.Quote from: CougarSE;167875I'm partial to Visio.Never heard of itQuote from: softtouch;168174Arc suppressing diodes should be used across the coils of relays when they are deenergized by opening a switch or another relays' contacts.The diode provides a circuit path for the current induced by the collapsing magnetic field of the relay coil.Without the diode, excessive arcing will shorten the life span of the switch or relay that opens the circuit.Some relays are made with this diode built into the assembly. It will have a polarity requirement for wireing the coil.I'm painfully aware of the arc suppressing diode thing, having given myself many a jolt - I put those diodes in my wig/wag flashers when I make them to prevent the spike from frying the timer circuit. In this particular application, though, they are not needed. The key word is "excessive" - if these relays were going to be subjected to constant on/off cycling a diode would be in order (such as in an A/C clutch relay, or, come to think of it, the A/C clutch itself), but since they will be cycled very little (once on they'll be on for hours, once off they'll be off for hours or days) the arcing will have little effect on the ignition switch. Maybe over 50 or so years in a daily driver it might wear the contacts in the ignition switch, but certainly not anytime soon... Quote Selected
I think I must be crazy... Reply #12 – August 12, 2007, 10:27:26 AM Quote from: Thunder Chicken;168181Never heard of itVIsio is a good program but imho, has one downside. It has all these aleady done up shapes like switches, valves, relays ect. The only bad part is everytime i try to use it, i dont have the shapes i would prefer.so,,,you have to build them.for example, a worm gear, i needed a worm gear once and all i had to select from were simple gears. Quote Selected
I think I must be crazy... Reply #13 – August 12, 2007, 10:07:58 PM Ok, so I've got the wiring finished. Now I've just got to get the ed dash back in. I'm gonna paint it black before doing so, though - gonna go with either an all black or a black/blue two-tone interior.The updated wiring diagram, changed to reflect the colours of the wires I actually used:Note that I had to swap two fuse positions around on the factory fuse panel. Now I've just gotta print this off and staple it into my EVTM and fold up a copy to be tucked into the owners manual, in case I ever have a problem with these circuits. Quote Selected
I think I must be crazy... Reply #14 – August 13, 2007, 04:00:30 PM After the trouble I've had with my harness last week, I'm thinking it's time to replace mine as well(wires blew WITHOUT blowing the fusible link on the starter relay!). Excellent diagrams! How do you paste text into paint? Quote Selected
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