Ford Mustang Forums
 Home Register FAQ New Posts Members List Contact Us     Log In Log In  
Ford Mustang Forums Tech Related How To Articles

Hiding underhood wiring harnesses

Benchracer 19.02.2007, 21:56
Hiding the main under-hood wiring harnesses on a í87-93 Fox Mustang

There are several main wiring harnesses on the í87-93 Mustangs under the hood that can be moved & hidden inside the fenders. On the drivers side there is a factory wiring harness that goes over the strut tower, between the strut mount plate and the fender. On the same side there is another harness that routes along inner structure at the base of the strut tower. There are battery cables and air-bag sensor wires that are below the battery tray. All of these converge at the fender mounted solenoid. On the passenger side there is one main harness that goes over the strut tower, between the strut mount plate and the fender. There are also air bag sensor harnesses under the factory air box area, or where the factory air box would be. These harnesses meet under the MAF (mass air flow) meter.

There are several different ways to hide all or part of these harnesses. I chose to remove both inner & outer fenders for this because I was replacing both fenders & bumper cover due to an accident. This can be done without removing the fenders. If you choose not to remove the fenders, I recommend having an assistant and removing the front wheels/tires.

***Depending on factory tolerances wires may need to be lengthened and/or the black tape-like wrapping peeled away to allow the wiring to move/free up. I DID NOT HAVE TO CUT OR SPLICE ANY WIRING. ***

Before you start make notes as to where everything plugs into, especially the solenoid. There is a HOT and a SWITCH side to the solenoid and reversing the connections will not be good. I suggest completing one side then moving to the next.

Disconnect the battery and remove it and the battery tray. Remove left fender and plastic inner fender (splash shield) OR you can just remove the inner fender (splash shield). Disconnect all wiring at the solenoid, coil, master cylinder, air conditioning connection on inner structure, and the air bag sensor harnesses under the windshield washer solenoid. Disconnect the windshield washer hose, electrical connector, and remove the reservoir. Unfasten the wiring harness from the plastic anchors that attach them to the car. Try not to break them because you can reuse some later. Inspect all wiring for any damages. It is easier to repair them now than once they are inside the fender. Locate the 2 large holes in the inner structure. One is on the back side of the strut tower. The other is just to the right of that and is an oval-this is where the washer fluid hose, vacuum line and brake lines go through. ALL CONNECTORS WILL FIT THROUGH THE HOLES WITHOUT CUTTING OR REMOVING THE WIRING FROM THE CONNECTOR. Route the wire loom with the large oval connector through the larger oval hole first. TAKE YOUR TIME. Put each connector through individually pulling the wiring though at the same time. I used the smaller hole for the other harness, but some only use the larger oval one. Once both harnesses are though the holes pull all excess slack through to the inside of the inner structure.
Wiring going through Left inner structure:

***Depending on your brake set-up you may not use the master cylinder pigtail. If you still need it you can peel back the black tape-like wrapping to free up enough wiring to go back through the hole and connect the master cylinder. As we all know every Mustang is different and some may need to cut and splice enough wiring to be able to reach the master cylinder*** Re-inspect the wiring to make sure nothing was damaged. Pull the harnesses along the bottom of the top inner structure (this would be directly under the lip that the fenders bolt to). Disconnect the small battery cable ground wire from the core support. Pull the air bag sensor harness and negative battery cable out from the front, you may need to remove the headlight, side marker and turn signal lamp to gain access. Route the air bag sensor wiring & battery cable around the outside of the inner structure. Keep them down low by the horns to make sure the windshield washer reservoir can be bolted back on.
Reattach battery cable ground wire to core support-you should be able to use the same hole it was originally in or you can create a new one out of sight. [At this time you can relocate the coil and solenoid to the inside of the fender area if you want. You can also route the starter and ground cables and A/C wiring UNDER the frame by the stabilizer bar to frame mount.] Reconnect both wiring harnesses to each other and to their proper components using the large round hole in the inner structure by the solenoid, where the washer fluid reservoir opening comes into the engine bay, to route the wiring pigtails. Donít worry if you didnít relocate the coil & solenoid, they will still all reach there respective components. Electrical tape or protect any exposed wiring or anything that might rub against it. Secure all wiring harnesses and cables. Be sure to provide adequate clearance for the plastic inner fender (splash shield) to fit properly. You can drill holes, use zip ties, whatever you can think of to secure the wiring from movement. Remount the windshield washer reservoir. Use reservoir mounting screw as ground for the air bag wiring ground wire. Reinstall battery tray and battery. Check all connections. Start vehicle to make sure everything is working correctly. Reinstall fender, lights and any other part removed.
Wiring inside Left inner fender finished:

Disconnect battery. Remove right fender and plastic inner fender OR you can remove just the plastic inner fender. [To remove fender first remove antennae mast, antennae base trim cover and the 4 attaching screws. Unplug antennae cable from rear of radio and pull cable out from behind dash, glove box, all the way to the right kick panel and coil freely in floor. Unbolt the fender and tilt outward. Pull the antennae cable out from the outside of the car. Now you can pull fender away.] Remove the factory air cleaner assembly if you still have one. Now would be a good time to replace the factory air cleaner with a CAI (cold air induction) kit, like the ones offered by Morroso, BBK, KNN, JLT and MAC just to name a few. Disconnect the purge/vapor return line from the valve on top of the emissions canister, located in front of the right stabilizer bar to frame mount. BE CAREFULL NOT TO DAMAGE ANY VACUUM LINES. Pull the vapor line back out of the strut tower so it is outside of the engine bay. Disconnect main wiring harness from the air bag sensor harness, MAF, A/C relay and purge valve. Remove plastic retaining clips. Check wiring for any damage and repair if needed. Pull the main harness to the rear of the strut tower and route through the hole at the rear of the strut tower. Pass the MAF connector through first then each other connector while pulling the wiring through at the same time. TAKE YOUR TIME. MAKE SURE NOT TO DAMAGE THE VACUUM LINES IN THE CORNER. After the harness is through the hole pull all excess slack through also. I chose to route the MAF and A/C relay wiring back into the engine bay through the large round hole in front of the strut tower. Some CAI systems put the MAF sensor in the fender and you may not want youíre A/C relay in the engine bay. You can easily mount it out in the fender.
Wiring harness going through Right inner structure:

Pull the air bag wiring harness out through the front of core support. You may have to remove the headlight, side marker and turn signal lamp.
Reconnect all wiring harnesses together. Evap purge solenoid wiring harness will be routed UNDER the frame structure along with the vapor line. Secure all wiring making sure the inner fender will have proper fitment. Reconnect battery and start the car to make sure everything works. Re-install the headlights, side markers, turn signal lamps, fenders, and air cleaner.
Wiring inside Right fender finished:

Overhead view of engine bay finished:
stangfather 20.02.2007, 15:57
nice writeup sir!!!

im trying to talk my buddy into doing the same thing.
Benchracer 20.02.2007, 22:02
if he or anyone has any questions you can call me.
onebad5.0 22.02.2007, 14:13
Looks good, I did the same thing on my car , and it's make's it look a lot cleaner under the hood.
cobracoupe 23.02.2007, 02:37
Great Article!! Will probably be doing some of this on my coupe in the near future. If I have any questions I will be sure to ask you. Looks great!!
89ragtoppony 23.02.2007, 04:00
thats a good write up, I was just fixing to start to do that to mine and that helped out alot thanksroxor
FoMoCo1 16.03.2007, 01:44
anyone have any pics of their starter solenoids mounted inside the fenderwell?
Benchracer 16.03.2007, 21:13
there were some on corral in this thread: ....

i didnt like the fact that there will be screws or bolts portuding into the engine bay. i saw one at a show that had mounted them inside the left fender along the bottom frame rail by the sway bar mount. he wasn't running fender liners but it looked like they clear.
xtreme2 20.08.2007, 07:26
Nice... I read about this in Super Street a few months ago... Been wanting to try it out... You really did well...
amentowasso 20.08.2007, 07:26
Nice... I read about this in Super Street a few months ago... Been wanting to try it out... You really did well...
BASixxer 20.08.2007, 07:26
Nice... I read about this in Super Street a few months ago... Been wanting to try it out... You really did well...
Similar Threads
Fox and 94-95 wiring harnesses
wiring harnesses for sale
240 straight 6,wiring harnesses, high torque starter, alum. flywheel, clutch, headers
Any idea what this thing is hiding underneath this hoodscoop?
FS:87-93 Underhood Insulator
Copyright © 2006-2019, Ford Mustang Forums. Privacy Policy