My Project Car...90 Gt

Bigsky said:

I ordered a new ignition switch and a new head light harness. Previously I installed the new dimmer switch and after the sun went down checked to see if it worked..hell no..no interior lights or running lights. So I pulled the head light switch (that should come out easier) and the brown wire was dangling..pushed it back in the harness and no audible click...the retainer must have broke.but I got it to light up...dimmer works great..so come on lmr...I want so bad to be done with the electrical

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In the PNW, if you order your parts early Monday morning you should get your parts on Friday when ordering from LMR. At least that's been my experience.

Bigsky said:

Ya...a Lot of my buddies listened to that stuff..driving down main street...4 guys in a car head banging...I went cruzing with the girls...something to be said for a high school chick with ratted out hair smelling like white rain and Marlboro reds...lol

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You just described my ex wife in high school! Damn that was funny. And White Rain!! Haven't heard/thought about that in a very long time. Just got an entire nostalgic "feel" from that posting...lmao

SEE Mustang GT Fog Light Fix to fix the foglight problem. The stock wiring isn't up to the job and is overheating. The headlight switch & turn/multifunction switch are affected by Ford's wiring problem. Sometimes it overheats so badly that the plastic shells of the wiring connectors start to melt. This will show you how to add a relay to the fog lights to relieve the overload on the headlight wiring.

Be careful not to use bulbs rated at more than 55 watt each with the stock fog light wiring. Using oversize bulbs can result in overheating the wiring harness and electrical fires. Definitely do the fog light fix first.

I did mine differently, but I had to build my own wiring harness for the fog lights. This is more trouble than it is worth for most folks. I left all the wiring on the stock light switches in place and used the fog light wiring to power the relay coil. The other side of the relay coil is connected to ground. I have an inline fuse that picks up power from the battery side of the starter solenoid. It is connected to the relay contact. The other relay contact is connected to the new wiring harness I made for the fog lights.



The advantage of making your own foglight wiring harness is that you can run 100 watt fog light bulbs. The stock wiring harness will not use 100 watt bulbs without overloading and causing a fire.

Unless you are good at electrical wiring, have the skills and tools (crimp tool, soldering gun, heat gun for the heat shrink tubing, etc.) I recommend that you stick with the Corral method.

Technical explanation of why the wiring and switches overheat.
You asked for it...

I= Current
E= Voltage
R= Resistance
W= Watts

Two 55 watt fog lamps =110 watts. Find the current in the circuit
I= W/E
110 watts/14 volts = 7.85 amps for fog lights alone.
Since the lighting circuit supplies headlights, taillights, and parking lights, etc.

56 watts 2 each GE Part # L3156 corner light 28 watts each
90 watts 2 each GE Part # 9004 headlight 45/65 watts each (low beam)
63 watts 2 each GE Part # L194 parking light 31.5 watts each
56 watts 2 each GE Part # L3157 tail light 28 watts each
265 watts Total

Total other exterior lighting current
I=W/E
265 watts/14 volts = 18.92 amps
18.92 amps other exterior lighting current
+ 7.85 amps fog light current
26.77 amps with all exterior lights and fog lights on.

The 12 gauge power feed wire to the exterior lighting switch is rated at 20 amps
26.77
- 20.00
6.77 amps excess current

7.85 amps used by fog lights
-6.77 amps excess current
1.08 amps to run the fog lights left if you stay within the 20 amp limit of the wire.
With 1.08 amp of current, the fog lights probably won’t produce any useable light.

Added resistance required to reduce fog light current to permissible 20 amp limit
R=E/I
14 volts/6.77 amps = 2.06 ohms
Resistor wattage
W=EI
14 volts x 6.77 amps = 94.78 watts
You would need a 2 ohm, 100 watt resistor.

Light bulb ratings from http://www.roadparts.com/catalog/section30.pdf
Radio shack resistor catalog - no matches , and no combinations that could be used to make a 100 watt, 2 Ohm resistor.
See RadioShack.com

Ohm’s law – in case you have any questions about my formulas - Ohm's Law Calculators

Bigsky said:

I reconnected the speedo cable and put dash back together. Took off front left tire and filed down brake pad retainer clip so it won't rub on rim.
Installed fog lights but they don't turn on... need a ratchet wrench to remove headlights..next weekend I need to get head lights installed, figure out fog light issue, change oil, fix leak in tire, diagnose map light issue, and determine failure of turn signal function.

Next major fix needs to be 5 lug conversion. Haven't decided if I want to go rear disk at this time or just get the five lug done so I can get new rims and snow tires... what ever I decide sub frame connectors are also on the near future agenda.

There are a few systems still in need of fixing...but they will require more education to fix. The air conditioner and cruise control are going to be on the agenda for this winter. I want them up and running next summer...hopefully I can get through this winter with my cracked windshield..(I'd hate to replace it in fall only to have it cracked a month later when they start sanding the roads)

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The rear disc can wait IMO. They only provide about 20% of the braking. Unless you're wanting the disc look right away, just check the pads, drums, and slave cylinder in the back.

I highly recommend the SFCs. The car will handle so much better with them welded in.

Looks like mine...lol

Davedacarpainter said:

The rear disc can wait IMO. They only provide about 20% of the braking. Unless you're wanting the disc look right away, just check the pads, drums, and slave cylinder in the back.

I highly recommend the SFCs. The car will handle so much better with them welded in.

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I know there is a cost difference in the various ways a 5 lug swap could be performed but for me personally when I went from 4 lug stock brakes to 13"/11.65" Cobra disc brakes the difference was amazing!! I would never recommend anything less.

FoxMustangLvr said:

I know there is a cost difference in the various ways a 5 lug swap could be performed but for me personally when I went from 4 lug stock brakes to 13"/11.65" Cobra disc brakes the difference was amazing!! I would never recommend anything less.

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I agree with that. I guess I'm thinking he's keeping the four lug for a bit.

FoxMustangLvr said:

I know there is a cost difference in the various ways a 5 lug swap could be performed but for me personally when I went from 4 lug stock brakes to 13"/11.65" Cobra disc brakes the difference was amazing!! I would never recommend anything less.

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I agree but you are looking at a min of $2000 when you factor in new rims and tires.... Debating this right now myself.

mikestang63 said:

I agree but you are looking at a min of $2000 when you factor in new rims and tires.... Debating this right now myself.

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True but nobody has a problem spending about $4k or more on an HCI combo or blower. $2k on wheels and excellent stopping power is well worth it and provides huge benefits. I did my current 5.0 backwards than most people would I guess, I began (this time) with brakes, handling and SFC's up front leaving HP next on my list of things to do. I'd like to think this is the "textbook" way to mod a Fox?

You're golden brother, most of us become children though and leap to the hp gains first.