Engine bay body wiring harness swap v6 cfi to v8 SEFI

November 10, 2016, 12:25:19 PM

Engine bay body wiring harness swap v6 cfi to v8 SEFI

for our 87coug build i thought i was going to share a long thread about "how to".
instead i have learned its not all that bad. you simply hook up wires color for color in most all instances.

Why i cut off the body harness to graft in a new one?
-The v6 cfi 87 year has the entire electrical distribution system opposite from the v8 meaning all things battery, power, sensors and such are just TOTALLY different.
-solution is to cut off the v6 body harness keeping it on hand to compare later against a donor v8 87 model harness.

Why did i pick an 87 5.0 body harness over the 88 model.
-i had procured an 88 5.0 body harness but was skeptical its integration would be smooth.
-same year means likelyhood of same color coding for stuff
-it is to be noted that 88 5.0 L is a one year only deal to the point lots of changes were made, this is why the 88 cougs/birds have a dedicated EVTM.
-i concluded i better stay clear of 88 wiring harnesses

existing car was 87 coug 3.8L v6 CFI application
-"standard" dash with electronic speedometer
-buttstuffog temp and fuel guages
-standard manual hvac (levers only)
-no climate control

donor body harness- 87 v8 cougar
-full digital "star wars" intrumentation
-electronic everything with respect to the instrument cluster
-climate control

in my transition from v6 to v8 wiring i have learned this
step 1
-extract and repin all matching wires to C294 (4pin conn) & C315 (8pin conn with 6 being used)
once you do this first step it will save you time later due to duplication in the "tan" and "Brn-W" wires.

step 2
-you have noticed in your donor harness there is no red blue for the start ckt
-you have noticed your car has a red blue waiting for you to connect it.
-for the v6cfi ford almost kept the start ckt completly pure as red-blue out to the engine bay
-for the V8 cars, ford allowed the white pink to serve the start function but red blue was used on the beginning and end of this ckt.
-connect your existing red/bl wire to your donor harness white/pink

step 3
-connect up all wires matching them for color codes including stripe configuration.

Step 4
-you will end up with spare wires On your "DONOR HARNESS" with no match on your pigtail existing body harness.
-identify thier function

~examples
-White / pink - see step 2

White/pink 2s tight
- this is for the oil pan low oil level sensor which we are not going to use so it was omitted
-this wire changes to a blue wire before hitting the oil pan sensor.

Orange/Yellow
- engine temp sensor exclusively used when you have EATC or "climate control".
a little more on this... most of us have a single wire sensor to feed our dash to tell us the engine temperature. for climate control application cars, this single wire sensor is not used but the wire is kept as spare in the harness. Ford has a dedicated separte connector to integrate this special sensor up near your air conditioner comperssor. We will not need this so on our donor harness the org / yel wire will be spared back and we will use the single wire slip on connector instead.

Pink / Yellow
-low washer fluid indicator
-we are going to find out if this can actually be added to the standard cluster with electronic speedo
-What we do know is that this wire is exclusive to the full digital dash system for fluid low notification

Black Yellow
-this wire ends up being bonded to your brake fluid and washer fluid ground wiring in parallel with an existing ground, somewhat redundant.
-we are keeping this ground but will bond it to the chassis in the engine bay.

Dark Green / yellow
-you will have already re-pinned this wire to C315 but notice it needs a fire wall connection. dead end this wire in the engine bay because its uses is intended for a full digital cluster and if you dont have the full digi cluster, spare it back.

odd ball wire that costed me a lot of time.........
White / Brown 2s on C315=
-this wire on our donor harness kicked my butt. it travels to pin 30 of the computer
-when you trace it inside it shows up on your ign sw as circuit #376. ***ALL documentation shows this conductor color should be yellow red!!
~ford must have used brn/w 2s for this circuit,, its function is unknown to me.

*some wires have 1 stripe such as what i called Brn-W 1s (brown white 1 stripe), or Brn-W 2s (brown white 2 stripe).

*some wires are the exact same color coding yet the stripes are not directly opposite.
example
Purple-white "tight" -stripes are closer together appearing to be on "one side" of the wire" meaning "tight stripes"
Purple-white - stripes are on opposite sides of the wire

*Some wires will have further down stream same colors such as Brown white with 2 stripes. The Brn-W wires at your front lights have very skinny white stripes but they come to a splice moving upstream closer to the power source and the main wire feed has thicker stripes.

We etched or painted on each connector, spice or fuse link the identication #.
Now with a visual inspection of the body harness the connector or splice or fuse link is visually ink stamped for future troubleshooting purposes.