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1st Generation 1964 1/2 - 1973 - Questions & general discussions that apply to a specific year => 1968 Mustang => Topic started by: bullitt68 on July 23, 2020, 03:57:19 AM

Title: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 03:57:19 AM
I just pulled out my wiring harnesses for the first time since removing them from the car and I am wondering if restoring them or replacing them is the way to go. The radio/8 track harness has been hacked up pretty bad. I think one of the door harnesses has been replaced. The rear wiring harness sheaths are falling apart. I thin that the engine bay harness has been reaped with electrical tape. The under dash harness looks to be in pretty good shape.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: 67gtasanjose on July 23, 2020, 05:39:36 AM
Underdash harness needs some repair work too but looks salvageable. If the under hood harness isn't too brittle it looks ok too. Taillight harness would take some work with new taillight sockets spliced in far enough back to be hidden under the weave. Rhode Island Harness can re-apply the weave, nothing aftermarket will look right so that might be a way to go. 8-track harness is reproduced. Door harnesses are also reproduced (Alloy Metal preferably) but they do not come with the locators so save your originals for parts. Convenience Control harness for 68's is not reproduced so you might need to rework yours, same with the Tilt-away harness.
Reproduction harnesses all have a trade-off in appearance so if possible, look for donor harnesses from other original cars for sections needed. You might be able to splice in reproduction ends for items such as the tailight ends (to get bright/shiny zinc dichromate finish) but I don't know where you would source those.

Hope this helps.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 05:47:04 AM
Underdash harness needs some repair work too but looks salvageable. If the under hood harness isn't too brittle it looks ok too. Taillight harness would take some work with new taillight sockets spliced in far enough back to be hidden under the weave. Rhode Island Harness can re-apply the weave, nothing aftermarket will look right so that might be a way to go. 8-track harness is reproduced. Convenience Control harness for 68's is not so you might need to rework yours, same with the Tilt-away harness.
Reproduction harnesses all have a trade-off in appearance so if possible, look for donor harnesses from other original cars for sections needed. You might be able to splice in reproduction ends for items such as the tailight ends (to get bright/shiny zinc dichromate finish) but I don't know where you would source those.

Hope this helps.

Thanks Richard. My under hood harness is pretty brittle compared too the rest. I think my convenience group harness is good. My tilt away system was missing when I got the car. I was planning to replace the 8 track harness. I was thinking of getting Rhode Island to restore the rear harnesses. I guess first I will try to clean them up and remove the tape and see how they look inside. Anything I should know about cleaning them, cleaning product etc
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: 67gtasanjose on July 23, 2020, 05:52:21 AM
Thanks Richard. My under hood harness is pretty brittle compared too the rest. I think my convenience group harness is good. My tilt away harness was missing when I got the car. I was planning to replace the 8 track harness. I was thinking of getting Rhode Island to restore the rear harnesses. I guess first I will try to clean them up and remove the tape and see how they look inside. Anything I should know about cleaning them, cleaning product etc
No easy way to clean them, there are a few threads discussing what others have used but stay off the tracer stripes as much as possible...you will wipe them off. I think lanolin hand cleaner is a recommended product. Search "Lanolin hand"

Re-read my comments in edit above about reproduction door harnesses. You replied before my edit came up.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 06:05:51 AM
No easy way to clean them, there are a few threads discussing what others have used but stay off the tracer stripes as much as possible...you will wipe them off. I think lanolin hand cleaner is a recommended product. Search "Lanolin hand"

Re-read my comments in edit above about reproduction door harnesses. You replied before my edit came up.

Great thanks I just re read you edited comments now
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: midlife on July 23, 2020, 08:59:34 AM
No easy way to clean them, there are a few threads discussing what others have used but stay off the tracer stripes as much as possible...you will wipe them off. I think lanolin hand cleaner is a recommended product. Search "Lanolin hand"

Re-read my comments in edit above about reproduction door harnesses. You replied before my edit came up.
I see this comment about staying away from tracer stripes.  For 12 years now, I have been cleaning with lacquer thinner on a rag which works quite well.  The only time I've seen wire colors be wiped away is on some fuel lines in the tail-light harness and fusible links near the starter solenoid.  In these cases, the wires have been painted due to the non-standard insulation (rubber-like substance).  Very rarely I've seen standard PVC wires also painted because the underlying colors were wrong for that application (ran out of that specific wire color during manufacturing?).  Again, very rare circumstances where wire colors get removed with cleaning.
Obviously, don't soak wires in any liquid or solvent.  You can wipe vigorously with any mild to moderate (up to lacquer thinner) cleaning agent without fear of losing colors.  The colors in the wires were embedded in the plastic at the time of wire manufacture and are not painted.  That's not so true today with modern replacement wires, as it is cheaper to paint the wires vice colorizing the insulation during manufacture.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: 67gtasanjose on July 23, 2020, 09:26:46 AM
I see this comment about staying away from tracer stripes.  For 12 years now, I have been cleaning with lacquer thinner on a rag which works quite well.  The only time I've seen wire colors be wiped away is on some fuel lines in the tail-light harness and fusible links near the starter solenoid.  In these cases, the wires have been painted due to the non-standard insulation (rubber-like substance).  Very rarely I've seen standard PVC wires also painted because the underlying colors were wrong for that application (ran out of that specific wire color during manufacturing?).  Again, very rare circumstances where wire colors get removed with cleaning.
Obviously, don't soak wires in any liquid or solvent.  You can wipe vigorously with any mild to moderate (up to lacquer thinner) cleaning agent without fear of losing colors.  The colors in the wires were embedded in the plastic at the time of wire manufacture and are not painted.  That's not so true today with modern replacement wires, as it is cheaper to paint the wires vice colorizing the insulation during manufacture.
Err on the side of caution then would be perhaps a better way to state it because lacquer thinner WAS used in cleaning some my harnesses and I did get some tracer paint wash off (rather easily) and others no issue (like you stated) but which is worse? I know there are essentially two grades of lacquer thinners on the market, one being a bit stronger than the other. I only buy the "good stuff" because it works where the other type does not.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 23, 2020, 10:49:40 AM
(http://thecoralsnake.com/before.jpg)

My advice, as a wiring salesman, replace them all. 😉

The red GT500 KR owner will support me on that.

Especially,  in light of the fact 5/8 photos are with splices already, you have stated the others are brittle. You can chase these for years or do it once. 

Lets get that tilt working also, instead of bypassing the wires!
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: jwc66k on July 23, 2020, 01:02:54 PM
I see this comment about staying away from tracer stripes.  For 12 years now, I have been cleaning with lacquer thinner on a rag which works quite well.  The only time I've seen wire colors be wiped away is on some fuel lines in the tail-light harness and fusible links near the starter solenoid. 
A big DON'T is use "Goof-Off" to clean wires. I recommended Goof-Off to a friend to remove road tar from his bumpers (64 1/2 Dearborn Convertible). He used it on some dirty wires in the engine compartment. It removed the wire tracers, but the wires were "clean". We did find NOS replacements.
Jim
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: 67gta289 on July 23, 2020, 01:26:52 PM
Xylene will clean nicely and leave the stripes alone.  PPE, gloves in this case, is tricky. Xylene eats latex and nomex gloves. 
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 02:32:27 PM
I see this comment about staying away from tracer stripes.  For 12 years now, I have been cleaning with lacquer thinner on a rag which works quite well.  The only time I've seen wire colors be wiped away is on some fuel lines in the tail-light harness and fusible links near the starter solenoid.  In these cases, the wires have been painted due to the non-standard insulation (rubber-like substance).  Very rarely I've seen standard PVC wires also painted because the underlying colors were wrong for that application (ran out of that specific wire color during manufacturing?).  Again, very rare circumstances where wire colors get removed with cleaning.
Obviously, don't soak wires in any liquid or solvent.  You can wipe vigorously with any mild to moderate (up to lacquer thinner) cleaning agent without fear of losing colors.  The colors in the wires were embedded in the plastic at the time of wire manufacture and are not painted.  That's not so true today with modern replacement wires, as it is cheaper to paint the wires vice colorizing the insulation during manufacture.

Thanks Randy appreciate the information
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 23, 2020, 02:32:39 PM
I dont recognize the fifth photo, do you recall what that underdash harness plugged into? Its the one with the relay in the center of the photo?
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 23, 2020, 02:36:15 PM
I donr recognize the fifth photo, do you recall what that underdash harness plugged into? The is the one with the relay in the center of the photo
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 02:36:31 PM
I dont recognize the fifth photo, do you recall what that underdash harness plugged into?

I didn't recall off hand what it is either. I will take a look as I labeled the bag it is in. I suspect that it is an under dash sub harness
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 23, 2020, 02:41:13 PM
Probably convienence control panel?
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 02:44:57 PM
Probably convienence control panel?

No I don't think so,  the convenience group harness has the 4 bulbs on it. Not sure if it is the Tilt-A-Way harness. I will check my tear down photos as well
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: midlife on July 23, 2020, 02:48:33 PM
I see what's part of the parking brake plug (I think...it could also be an AC plug), but the rest of the harness looks like nothing I've seen before.  It could just be how the photo was taken which doesn't show much of the plugs.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 02:50:21 PM
I see what's part of the parking brake plug (I think...it could also be an AC plug), but the rest of the harness looks like nothing I've seen before.  It could just be how the photo was taken which doesn't show much of the plugs.

I don't have AC on my car. Its not a great photo is it. The plugs are facing down and the relay or whatever it is is not shown. I will take a better photo
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 23, 2020, 03:31:32 PM
I see the tilt harness. It is photo # 7
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 23, 2020, 03:46:58 PM
Im thinking thats convienence control and the purple green wires are seat belt warning.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: bullitt68 on July 23, 2020, 04:18:52 PM
I see the tilt harness. It is photo # 7

Ok good to know. My tilt-a-way vacuum system was not functional. Someone replaced it with and electric solenoid set up at some point.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 23, 2020, 07:09:55 PM
They have bypassed the neutral safety switch of the tilt electrical wiring too...
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: 67gtasanjose on July 24, 2020, 05:24:02 AM
I dont recognize the fifth photo, do you recall what that underdash harness plugged into? Its the one with the relay in the center of the photo?

5th picture is of the Convenience Group  harness.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: 67gtasanjose on July 24, 2020, 05:32:25 AM
They have bypassed the neutral safety switch of the tilt electrical wiring too...
I saw that too.

Those two wires should reach over to the connection to the starter interruption switch of the Tilt-away feature. I am not well versed in the 68 version of that circuit, I only know it prevents the starter from working by interrupting the solenoid wire while the wheel is tilted away.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: Coralsnake on July 24, 2020, 06:43:00 AM
The safety switch is common to all tilt cars. “Neutral” safety may have been misleading. The switch is inside the vacuum motor and does not allow the car to start when the wheel is in an offset position.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: 67gtasanjose on July 24, 2020, 09:12:37 AM
The safety switch is common to all tilt cars. “Neutral” safety may have been misleading. The switch is inside the vacuum motor and does not allow the car to start when the wheel is in an offset position.
Ahhhhhh, yes...duh! I knew that! That one of the two Tilt-away harnesses is plugged into the main underdash harness "interupting" the starter solenoid wire at one of the under dash connectors (of the under hood harness ~located left of steering column). The ACTUAL neutral safety/reverse lamp connector is under the hood (above the throttle pedal arm), where the "loop" for a manual transmission car would be found.

I have amended my earlier reply to help others avoid confusion.
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: preaction on January 21, 2021, 05:20:19 PM
In picture #2 of the OP which is the engine compartment harness the two horn leads are finished differently, the passenger side lead has a plastic "tube"  running the length of the wire and the drivers side has been taped as is the rest of the harness Im in the process of going over my harness which has been finished in the same way is there a known reason for this ?
Title: Re: 1968 San Jose GT 390 Fastback Wiring Harness Restoration
Post by: J_Speegle on January 21, 2021, 05:28:53 PM
In picture #2 of the OP which is the engine compartment harness the two horn leads are finished differently, the passenger side lead has a plastic "tube"  running the length of the wire and the drivers side has been taped as is the rest of the harness Im in the process of going over my harness which has been finished in the same way is there a known reason for this ?

Done on a number of the model years. Have no idea of why Ford and their employees designed it that way but since it cost money there must have been a reason.