Cleaning up engine wiring

KiltedBanshees93GT · 01-30-2004, 11:18 AM

One of my (many) projects that I'm working on is the '66's wiring, and I may be replacing portions (at the minimum) of the wiring harness. If I'm going to be doing this anyway, I was wondering if anyone had any tips/pointers to info as to the best way to clean up an engine bay, hide wiring/reroute things for a cleaner apperance. I may also (eventually) be doing the same thing to my 93. Are there any books, articles etc. that I should know about?
I figure I can go through and "rebuild" the underhood harness on my own, but any advice from those who have done it already would be appreciated and make the job easier.
Thanks,
Jorge

Rex_A_Lott · 02-02-2004, 08:10 PM

I stumbled onto this board today, looking for info.
There is a company called Painless Wiring that sells pre-fabbed wiring harnesses to do what you're looking for.
Search for them on Google..

KiltedBanshees93GT · 02-03-2004, 09:26 AM

Actually I know about the painless harness, its basically a bolt in replacement (I may be buying one depending on how bad the underdash is bodged up), my question was more directed toward the best ways/tips to "modify" a new or existing harness for a clean underhood appreance. (i.e. re routing the wires through the fenders, move the solenoid to a more inconspicious place etc.)
I know the general principles, ideas etc, but was wondering if the folks that have done this before might have any ideas/pointers etc.
Thanks again,

J

Jeff65 · 02-03-2004, 03:19 PM

Here's what I did to my '65:

a. Removed the harnesses.
b. Examined each for layout, condition and connectors. Determined what to fix.
c. Bought an old harness from a early Falcon to salvage connectors and wire from (couldn't find a Mustang). Paid $5 for the Falcon under dash harness.
d. Untaped segments of the wire as needed to repair.

Substituted connectors when needed and as they fit to make a good Mustang harness. All bad wiring was cut out and replaced with good wire segments and connectors. Restomod wiring and connectors were included in the reworked harness. Wiring was carefully re-taped. Black heat shrink was used over taped ends to ensure they wouldn't unravel. Harness was continuity checked according to schematic drawing to ensure all wiring was correct.

Yes, I made AutoCad drawings for all wiring revisions so the next owner of my car can figure out what circuits are added.

Wiring was reinstalled in car and then tested. Several problems developed but they were found and fixed before the dash was closed up.

Wiring over engine was enclosed in temperature protected sleeving (vinyl-glass) to ensure it didn't deteriorate with age. Routing over engine was spaced off with vinyl clamps somewhat like the OEM clamps (purchased at Ace Hardware). When new starter cable was installed, it was also enclosed in glass sleeving to protect it from header heat. A factory standoff (reproduction) was used before and after the passenger side motor mount to ensure it stayed put.

In the underhood area I used split flex tubing (black) to cover the wire runs and held them in position using OEM straps. For custom areas (like T5 neutral safety and back up lights) I used self adhesive wiring mounting pads (aircraft part). These can be purchased at electronics supply stores. What it is is little square adhesive-backed nylon pads that stick to any clean surface. On the front side there are loops for nylon ties. Route the wire bundle across the top of the pad then lash the nylon around the wire and through the loops on the nylon pads. No body modifications are needed and the little pads hold very securely. Wires don't go anywhere you don't want them to go. These work well and judges never notice how its done, they simply note that your engine compartment wiring looks super neat!

It's been several years now since the restoration and it was well worth the effort...cost was $5 and my time and energy. Cost savings was equal to the cost of new harnesses. It works...just take your time and do it right.

KiltedBanshees93GT · 02-04-2004, 10:38 AM

Thanks man, Thants exactly the type of ideas I was looking for, my 93 will be up and legal soon, so I will have more time to work on the 66 and actually take the harness apart. I just got a new fuel gauge, now I just have to find out where the harness is shorting the gauges out. (Oddly enough, about a month ago the temp gauge decided to work once...once, then it crapped out again

)
Anyway, thanks for the ideas. I've already laid in my supplies for redoing the harness, just been waiting for an alternate vehicle to be available. Great idea about the falcon harness, I wouldnt have thought of that. Where did you find it? None of the yards around here seem to have anything under mid 70's vehicles.

Thanks

Jorge

Jeff65 · 02-04-2004, 11:33 AM

99% of the time the instrument is shorted to the back shell. The backshell is metal and its grounded. The instrument posts (screws) stick through enlarged holes in the backshell. A fiber washer (non-conductor) holds the instrumented centered once the post nuts are tightened.

If, for example, the instrument is centered, then turned in the backshell until the posts touch or hit the backshell then you have a shorting condition. One of two things happens:

If the short is to the (+) side of the instrument, it shorts the constant voltage regulator (CVR) usually frying it (toast). Replacing the without correcting the problem usually toasts the new CVR too.

If the short is to the (-) grounded side of the instrument, it causes the instrument to read full scale. Thus, for fuel, the tank would always read full; or for temperature the engine temperature would always read hot, etc.

Whenever you work on the backshell or on instruments...make absolutely sure no shorts exist between instrument posts and the backshell. An ohmmeter works fine to check between post and backshell for these kind of short circuits.

Jeff

Lou Lyman · 02-04-2004, 06:11 PM

This link might be of interest to you.

http://www.midnightdsigns.com/Mustang/CustomWiring.html

Lou

Rex_A_Lott · 02-04-2004, 09:18 PM

Neat job Lou!!
Thanks for the tips and the pics.

KiltedBanshees93GT · 02-05-2004, 08:55 AM

Lou, looks good, Thanks again, this is exactly the type of info I was looking for.
Jeff, I just got a new fuel gauge because previously when I was wiring the new IVR in, something grounded for a second, and the old fuel gauge toasted. (Werent you emailing me with the troubleshooting suggestions? Sorry, I lost the actual emails and thus your address, this would have been in oct/nov) All the other gauges are ok, and work properly when hooked to the correct voltage. The short is somewhere in the harness. Now I just have to find it.
Anyway, thanks for the info again, some time within the next 2 weeks the 93 will be up again, and I'll be able to tear into the 66 and really start fixing some of this stuff.

Jorge

Lou Lyman · 02-05-2004, 11:44 AM

Don't misunderstand. That hidden wireing is not my car. It belongs to JamesW who has a lot of great tips on his website. James deserves the credit (or should I have just kept my mouth shut). Link below.

http://www.midnightdsigns.com/james/

Lou

01-30-2004, 11:18 AM	#1
KiltedBanshees93GT Registered Member Join Date: Jun 2000 Location: Pigeon Forge Tn Posts: 611	Cleaning up engine wiring One of my (many) projects that I'm working on is the '66's wiring, and I may be replacing portions (at the minimum) of the wiring harness. If I'm going to be doing this anyway, I was wondering if anyone had any tips/pointers to info as to the best way to clean up an engine bay, hide wiring/reroute things for a cleaner apperance. I may also (eventually) be doing the same thing to my 93. Are there any books, articles etc. that I should know about? I figure I can go through and "rebuild" the underhood harness on my own, but any advice from those who have done it already would be appreciated and make the job easier. Thanks, Jorge __________________ ____________ '66 Mustang Coupe- AKA "Lenore" on disability for a (long) bit '93 GT Mostly stock AKA "Fawkes" Rice Haters Club Member #239 "I find your lack of faith...disturbing." "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats." H. L. Mencken

02-02-2004, 08:10 PM	#2
Rex_A_Lott Registered Member Join Date: Feb 2004 Posts: 2	Wiring I stumbled onto this board today, looking for info. There is a company called Painless Wiring that sells pre-fabbed wiring harnesses to do what you're looking for. Search for them on Google..

02-03-2004, 09:26 AM	#3
KiltedBanshees93GT Registered Member Join Date: Jun 2000 Location: Pigeon Forge Tn Posts: 611	Actually I know about the painless harness, its basically a bolt in replacement (I may be buying one depending on how bad the underdash is bodged up), my question was more directed toward the best ways/tips to "modify" a new or existing harness for a clean underhood appreance. (i.e. re routing the wires through the fenders, move the solenoid to a more inconspicious place etc.) I know the general principles, ideas etc, but was wondering if the folks that have done this before might have any ideas/pointers etc. Thanks again, J __________________ ____________ '66 Mustang Coupe- AKA "Lenore" on disability for a (long) bit '93 GT Mostly stock AKA "Fawkes" Rice Haters Club Member #239 "I find your lack of faith...disturbing." "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats." H. L. Mencken

02-04-2004, 10:38 AM	#5
KiltedBanshees93GT Registered Member Join Date: Jun 2000 Location: Pigeon Forge Tn Posts: 611	Thanks man, Thants exactly the type of ideas I was looking for, my 93 will be up and legal soon, so I will have more time to work on the 66 and actually take the harness apart. I just got a new fuel gauge, now I just have to find out where the harness is shorting the gauges out. (Oddly enough, about a month ago the temp gauge decided to work once...once, then it crapped out again ) Anyway, thanks for the ideas. I've already laid in my supplies for redoing the harness, just been waiting for an alternate vehicle to be available. Great idea about the falcon harness, I wouldnt have thought of that. Where did you find it? None of the yards around here seem to have anything under mid 70's vehicles. Thanks Jorge __________________ ____________ '66 Mustang Coupe- AKA "Lenore" on disability for a (long) bit '93 GT Mostly stock AKA "Fawkes" Rice Haters Club Member #239 "I find your lack of faith...disturbing." "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats." H. L. Mencken

02-04-2004, 06:11 PM	#7
Lou Lyman Registered Member Join Date: Dec 1998 Location: Tampa, FL Posts: 70	This link might be of interest to you. http://www.midnightdsigns.com/Mustang/CustomWiring.html Lou __________________ Enjoy what you do. Do what you enjoy.

02-03-2004, 03:19 PM	#4
Jeff65 Registered Member Join Date: Jul 2002 Location: Oklahoma City Posts: 208	Here's what I did to my '65: a. Removed the harnesses. b. Examined each for layout, condition and connectors. Determined what to fix. c. Bought an old harness from a early Falcon to salvage connectors and wire from (couldn't find a Mustang). Paid $5 for the Falcon under dash harness. d. Untaped segments of the wire as needed to repair. Substituted connectors when needed and as they fit to make a good Mustang harness. All bad wiring was cut out and replaced with good wire segments and connectors. Restomod wiring and connectors were included in the reworked harness. Wiring was carefully re-taped. Black heat shrink was used over taped ends to ensure they wouldn't unravel. Harness was continuity checked according to schematic drawing to ensure all wiring was correct. Yes, I made AutoCad drawings for all wiring revisions so the next owner of my car can figure out what circuits are added. Wiring was reinstalled in car and then tested. Several problems developed but they were found and fixed before the dash was closed up. Wiring over engine was enclosed in temperature protected sleeving (vinyl-glass) to ensure it didn't deteriorate with age. Routing over engine was spaced off with vinyl clamps somewhat like the OEM clamps (purchased at Ace Hardware). When new starter cable was installed, it was also enclosed in glass sleeving to protect it from header heat. A factory standoff (reproduction) was used before and after the passenger side motor mount to ensure it stayed put. In the underhood area I used split flex tubing (black) to cover the wire runs and held them in position using OEM straps. For custom areas (like T5 neutral safety and back up lights) I used self adhesive wiring mounting pads (aircraft part). These can be purchased at electronics supply stores. What it is is little square adhesive-backed nylon pads that stick to any clean surface. On the front side there are loops for nylon ties. Route the wire bundle across the top of the pad then lash the nylon around the wire and through the loops on the nylon pads. No body modifications are needed and the little pads hold very securely. Wires don't go anywhere you don't want them to go. These work well and judges never notice how its done, they simply note that your engine compartment wiring looks super neat! It's been several years now since the restoration and it was well worth the effort...cost was $5 and my time and energy. Cost savings was equal to the cost of new harnesses. It works...just take your time and do it right.

02-04-2004, 11:33 AM	#6
Jeff65 Registered Member Join Date: Jul 2002 Location: Oklahoma City Posts: 208	99% of the time the instrument is shorted to the back shell. The backshell is metal and its grounded. The instrument posts (screws) stick through enlarged holes in the backshell. A fiber washer (non-conductor) holds the instrumented centered once the post nuts are tightened. If, for example, the instrument is centered, then turned in the backshell until the posts touch or hit the backshell then you have a shorting condition. One of two things happens: If the short is to the (+) side of the instrument, it shorts the constant voltage regulator (CVR) usually frying it (toast). Replacing the without correcting the problem usually toasts the new CVR too. If the short is to the (-) grounded side of the instrument, it causes the instrument to read full scale. Thus, for fuel, the tank would always read full; or for temperature the engine temperature would always read hot, etc. Whenever you work on the backshell or on instruments...make absolutely sure no shorts exist between instrument posts and the backshell. An ohmmeter works fine to check between post and backshell for these kind of short circuits. Jeff

02-04-2004, 09:18 PM	#8
Rex_A_Lott Registered Member Join Date: Feb 2004 Posts: 2	Neat job Lou!! Thanks for the tips and the pics.

02-05-2004, 08:55 AM	#9
KiltedBanshees93GT Registered Member Join Date: Jun 2000 Location: Pigeon Forge Tn Posts: 611	Lou, looks good, Thanks again, this is exactly the type of info I was looking for. Jeff, I just got a new fuel gauge because previously when I was wiring the new IVR in, something grounded for a second, and the old fuel gauge toasted. (Werent you emailing me with the troubleshooting suggestions? Sorry, I lost the actual emails and thus your address, this would have been in oct/nov) All the other gauges are ok, and work properly when hooked to the correct voltage. The short is somewhere in the harness. Now I just have to find it. Anyway, thanks for the info again, some time within the next 2 weeks the 93 will be up again, and I'll be able to tear into the 66 and really start fixing some of this stuff. Jorge __________________ ____________ '66 Mustang Coupe- AKA "Lenore" on disability for a (long) bit '93 GT Mostly stock AKA "Fawkes" Rice Haters Club Member #239 "I find your lack of faith...disturbing." "Every normal man must be tempted at times to spit on his hands, hoist the black flag, and begin to slit throats." H. L. Mencken

02-05-2004, 11:44 AM	#10
Lou Lyman Registered Member Join Date: Dec 1998 Location: Tampa, FL Posts: 70	Don't misunderstand. That hidden wireing is not my car. It belongs to JamesW who has a lot of great tips on his website. James deserves the credit (or should I have just kept my mouth shut). Link below. http://www.midnightdsigns.com/james/ Lou __________________ Enjoy what you do. Do what you enjoy.

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