Tutorial For Building Your Own S4+ Engine Wire Harness?
01-30-2017, 08:25 PM
#46
As an engineer with all the crimping tools available to me, I actually went through the process of looking into making a replacement harness myself.
Sean is correct when he says it's not easy to find a company that will sell quality marine cable by the foot for a reasonable price. Rounding up to the nearest foot, pricing out all the cables, the one-off connectors, the proper adhesive-lined heat-shrink tubing, the fire insulation, etc... the price was in the hundreds of dollars all said and done. So, if you feel like saving maybe $200 to create an essential component for the car that could potentially short out and/or ruin the sensitive Porsche electronics, be my guest. I went ahead and ordered a harness from him and couldn't be happier. I've seen the spools of cable in his garage, he has quality materials.
The main engine harness, along with other detail work like wrapping a dash/pod, paint/body work, HVAC, and tire/alignment issues are some of things I have no problem farming out to more experienced individuals with the proper tools. Everything else mechanical is done in my own garage.
Sean is correct when he says it's not easy to find a company that will sell quality marine cable by the foot for a reasonable price. Rounding up to the nearest foot, pricing out all the cables, the one-off connectors, the proper adhesive-lined heat-shrink tubing, the fire insulation, etc... the price was in the hundreds of dollars all said and done. So, if you feel like saving maybe $200 to create an essential component for the car that could potentially short out and/or ruin the sensitive Porsche electronics, be my guest. I went ahead and ordered a harness from him and couldn't be happier. I've seen the spools of cable in his garage, he has quality materials.
The main engine harness, along with other detail work like wrapping a dash/pod, paint/body work, HVAC, and tire/alignment issues are some of things I have no problem farming out to more experienced individuals with the proper tools. Everything else mechanical is done in my own garage.
04-12-2017, 10:28 AM
#47
Rennlist Member
Thread Starter
Chris--
If you have the old harness out on the floor, PM me with the lengths of the various conductors in my list. Also, let me know if the list is accurate; as much as I trust the wiring diagrams, there's No Substitute for actual hands-on inspection.
As far as the connectors, the only one that could be "updated" is the T18 connector, the 14-pin on the right side fenderwall. While one might be tempted to replace it with a Weatherpak or similar to make it truly waterproof, mine would stay as original. For sure I'd put new shell and pins in the upper half where the KS2 harness connects. At the other ends of each conductor, the terminals need to mate with each final element there. All except the 3-pin oil pressure sender and the boot for the oil level switch are common items.
Note that there are more than a few different variations on the wiring harness theme. Different years have differing wires and connections. Enough so that there's no single 'fitzall' assembly option.
Folks who have gone through the trouble of sourcing and investing in the various conductors, connectors and protective sleeves will tell you that doing just one yourself is not that easy. Greg's harness has a lot of careful thought put into conductors size upgrades, sleeve and thermal insulation, and some pretty excellent workmanship. I'm sure that SeanR and others are looking at the same effort and results when they build their harnesses.
And, while we are getting more familiar with the front of engine harness, the top of engine wiring for injection and sensors needs the same if not more attention. So throttle switch, idle air controller, knock sensors, temp sensors, flappy solenoid, MAF, injectors, CPS, Hall sensor, and undoubtedly more stuff, all living at the ends of some pretty crispy wiring by now.
And yes, I have modeled and built a few wiring harnesses.
Related: Several decades ago now, the local to me at the time aircraft factory was making their own wiring assemblies. The first airframe had prototype harnesses built in place, then removed to duplicate via BIG nail-boards. In actual assembly though, some of the production airframes had hydraulics and other systems in place before wiring was installed, so access and routing needed to be ever so slightly different. None of the fabricated wiring assemblies for those sections were usable. And it turned out that putting wire in before hydraulics and control cables caused random damage to any wiring already in place. And service parts might be totally different, depending on available access at the time of repair.
Maybe making a 928 front engine harness isn't so tough, considering all the possibilities. At least we know where and to what it needs to fit.
If you have the old harness out on the floor, PM me with the lengths of the various conductors in my list. Also, let me know if the list is accurate; as much as I trust the wiring diagrams, there's No Substitute for actual hands-on inspection.
As far as the connectors, the only one that could be "updated" is the T18 connector, the 14-pin on the right side fenderwall. While one might be tempted to replace it with a Weatherpak or similar to make it truly waterproof, mine would stay as original. For sure I'd put new shell and pins in the upper half where the KS2 harness connects. At the other ends of each conductor, the terminals need to mate with each final element there. All except the 3-pin oil pressure sender and the boot for the oil level switch are common items.
Note that there are more than a few different variations on the wiring harness theme. Different years have differing wires and connections. Enough so that there's no single 'fitzall' assembly option.
Folks who have gone through the trouble of sourcing and investing in the various conductors, connectors and protective sleeves will tell you that doing just one yourself is not that easy. Greg's harness has a lot of careful thought put into conductors size upgrades, sleeve and thermal insulation, and some pretty excellent workmanship. I'm sure that SeanR and others are looking at the same effort and results when they build their harnesses.
And, while we are getting more familiar with the front of engine harness, the top of engine wiring for injection and sensors needs the same if not more attention. So throttle switch, idle air controller, knock sensors, temp sensors, flappy solenoid, MAF, injectors, CPS, Hall sensor, and undoubtedly more stuff, all living at the ends of some pretty crispy wiring by now.
And yes, I have modeled and built a few wiring harnesses.
Related: Several decades ago now, the local to me at the time aircraft factory was making their own wiring assemblies. The first airframe had prototype harnesses built in place, then removed to duplicate via BIG nail-boards. In actual assembly though, some of the production airframes had hydraulics and other systems in place before wiring was installed, so access and routing needed to be ever so slightly different. None of the fabricated wiring assemblies for those sections were usable. And it turned out that putting wire in before hydraulics and control cables caused random damage to any wiring already in place. And service parts might be totally different, depending on available access at the time of repair.
Maybe making a 928 front engine harness isn't so tough, considering all the possibilities. At least we know where and to what it needs to fit.
Also Bob, if you have this in an Excel file could you PM me? I'd love to have it electronic so I can edit it for my needs, and I don't want to reinvent the wheel. Thanks.
05-02-2017, 12:33 PM
#52
Rennlist Member
Thread Starter
Definitely. Thanks John. I'm eager, and not intimidated in the least. Been testing crimp tools/methods at work trying to get things just right. Should be nice once complete. My only issue is I don't know if I want to change the oil pressure sender and forget about trying to salvage the goofy 3 pin connector. What did you do??
05-02-2017, 01:21 PM
#53
Rennlist Member
Thread Starter
Like everyone else I eliminate the 3 pin and swap over to the two pin pressure sending unit. The 3rd pen (brown/green wire) is a secondary ground to the instrument cluster. Can't find any reason for it as there is no loss of functionality with it gone, all functions remain. We've been trying for years to get Porsche to get that 3 pin in production but no word on that.
05-02-2017, 01:25 PM
#54
Sean, once I had cut the old harness open I found that the ground wire on the 3 pin connector was Brown with a Red tracer, instead of a Green tracer. I've read of one other Rennlister having a Red tracer as well. I wonder what the deal is on that? Not that it makes a difference, but I'm just curious. I'm on the fence on trying to salvage the 3 pic connector and keeping the current sender, or swap to the 2 pin 88< sender.
If your 3 pin connector can be re-used, then do so for originality reasons, I've had a few sent to me by customers so I can put it on the new harness, it's rare though.
05-02-2017, 02:37 PM
#55
Rennlist Member
Thread Starter
I've seen that too but didn't feel like ordering another spool of wire for it so I've been using the one I have on hand. I may change it up once I run out of this wire but I seldom use it so it may be a long while.
If your 3 pin connector can be re-used, then do so for originality reasons, I've had a few sent to me by customers so I can put it on the new harness, it's rare though.
If your 3 pin connector can be re-used, then do so for originality reasons, I've had a few sent to me by customers so I can put it on the new harness, it's rare though.
Cool. Thanks. Yeah I "think" I can salvage it, but will know for sure this weekend.
I had already ordered the Brown/Green, but since it was only $7.00 for 10ft, I went ahead and got the Brown/Red as well.
05-11-2017, 10:44 AM
#57
Shameful Thread Killer
Rennlist Member
Rennlist Member
Most wire harnesses with more than just a few wires use a flat loom frame. If you have a 4x8 sheet of plywood, and some medium finish nails, you can lay it out like a train-track set using the nails. Then loop the wires around the nails where the orig loom bends and shape would be. Seems like you want to do this right, and you'll need that bending frame to get it all aligned right.
BTW, when I did my repair to the under-hood harness, I did it with the harness in the car. I replaced some of the sense wires, and repaired by splicing some of the larger wires across the front. It's been holding up for a long time with just average plastic wire, but I haven't driven the car in 9 years. I looked at it the other day, and those wires are still in there, and still in good condition. However, I agree that marine quality wiring is a good thing.
BTW, when I did my repair to the under-hood harness, I did it with the harness in the car. I replaced some of the sense wires, and repaired by splicing some of the larger wires across the front. It's been holding up for a long time with just average plastic wire, but I haven't driven the car in 9 years. I looked at it the other day, and those wires are still in there, and still in good condition. However, I agree that marine quality wiring is a good thing.
05-11-2017, 03:00 PM
#58
Rennlist Member
I love the willingness of our board members to dive in to any operation.
After Carl's post above, I googled "Deutsche Motorsports or aero style connectors" and arrived at the tutorial below at rbracing-rsr.com. Lotso text and lotso images, quite a great production. An excellent resource with a lot of internal resources.
Professional Mil-Spec Motorsport ECU Wiring Harness Construction
https://www.rbracing-rsr.com/wiring_ecu.html
05-12-2017, 07:29 AM
#59
Rennlist Member
Professional Mil-Spec Motorsport ECU Wiring Harness Construction
https://www.rbracing-rsr.com/wiring_ecu.html
https://www.rbracing-rsr.com/wiring_ecu.html
05-12-2017, 07:40 AM
#60
Rennlist Member
Thread Starter
Most wire harnesses with more than just a few wires use a flat loom frame. If you have a 4x8 sheet of plywood, and some medium finish nails, you can lay it out like a train-track set using the nails. Then loop the wires around the nails where the orig loom bends and shape would be. Seems like you want to do this right, and you'll need that bending frame to get it all aligned right.
BTW, when I did my repair to the under-hood harness, I did it with the harness in the car. I replaced some of the sense wires, and repaired by splicing some of the larger wires across the front. It's been holding up for a long time with just average plastic wire, but I haven't driven the car in 9 years. I looked at it the other day, and those wires are still in there, and still in good condition. However, I agree that marine quality wiring is a good thing.
BTW, when I did my repair to the under-hood harness, I did it with the harness in the car. I replaced some of the sense wires, and repaired by splicing some of the larger wires across the front. It's been holding up for a long time with just average plastic wire, but I haven't driven the car in 9 years. I looked at it the other day, and those wires are still in there, and still in good condition. However, I agree that marine quality wiring is a good thing.