Wiring harness replacement
Chronic Tool Dropper
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From: Bend, Oregon
Chris--
Have you talked to 928 International yet? I know from the other thread that you shipped the car off to your mechanic, but at some point you will want to have the replacement parts.
Have you talked to 928 International yet? I know from the other thread that you shipped the car off to your mechanic, but at some point you will want to have the replacement parts.
Burning Brakes
Joined: Jul 2005
Posts: 955
Likes: 2
From: Nashville x-burbs
I searched the 928 Intl website and it is unclear how to name the harness(es) that I need. However, the cost seems high since I have no way of knowing if the DME is also dead, etc.
The search for used parts is on, and I can only hope this project is not too lengthy.
Does anyone have an idea how many labor hours are required to install the wiring harness that runs to the box between the passenger seat and door? One of those wires melted all the way to the fusebox when they shorted together.
Interestingly, only one fuse blew, which is a 5 amp fuse (#24). And on the fusebox itself, only one small wire fried. It's a red wire that goes to the top right corner of the blue (Q) plug. If I could decipher the schematics this might solve the mystery... if I can find an affordable harness (and possibly DME).
As my grandpa used to say, "If we had some ham we'd have some ham and eggs... IF we had some eggs..."
I've posted the car for sale for $5300 as a parts car that ran great before I burnt up the wiring harness. If someone wants a good 32v engine auto transmission, this would make a great parts car.
The search for used parts is on, and I can only hope this project is not too lengthy.
Does anyone have an idea how many labor hours are required to install the wiring harness that runs to the box between the passenger seat and door? One of those wires melted all the way to the fusebox when they shorted together.
Interestingly, only one fuse blew, which is a 5 amp fuse (#24). And on the fusebox itself, only one small wire fried. It's a red wire that goes to the top right corner of the blue (Q) plug. If I could decipher the schematics this might solve the mystery... if I can find an affordable harness (and possibly DME).
As my grandpa used to say, "If we had some ham we'd have some ham and eggs... IF we had some eggs..."
I've posted the car for sale for $5300 as a parts car that ran great before I burnt up the wiring harness. If someone wants a good 32v engine auto transmission, this would make a great parts car.
Instructor
Joined: Aug 2006
Posts: 142
Likes: 12
From: SF Bay Area, CA
Jim,
How long after power loss do you have to shut off the engine before it catches things on fire? (Ballpark guess) Also, I am still not entirely clear on how this occurs -- Does this only affect the 928's with dual distributors? How can you lose spark to only half the cylinders? It seems like it would be all or nothing.
Cambria,
Keep your eyes out for a parts car -- Sometimes you can get them really cheap (< $1000)...
How long after power loss do you have to shut off the engine before it catches things on fire? (Ballpark guess) Also, I am still not entirely clear on how this occurs -- Does this only affect the 928's with dual distributors? How can you lose spark to only half the cylinders? It seems like it would be all or nothing.
Cambria,
Keep your eyes out for a parts car -- Sometimes you can get them really cheap (< $1000)...
Chronic Tool Dropper
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From: Bend, Oregon
Foz--
The cat fire situation is pretty serious. The amount of time involved can be short or long, depending on the load on the engine and therefore the amount of fuel you are pushing into the cats.
It tends to affect the dual-distributor cars. The cars with dual coils have duplicate wiring and electrics for everything, so the car could be put in 4-cyl mode by anything from a coil to a coil wire to a distributor rotor or cap, also a failure of the ignition amplifier on the front apron. Chris suffered his problem when a coil wire was not properly reconnected after a TB change. Cambria had a similar problem and outcome.
So, if you have a S4 '87 or '88, or a pre-S4 car with two distributors (includes Euro US conversions with cats installed) and you feel the engine power drop, pull over and stop rather than trying to limp home in 4-cyl mode. '89 and newer cars have thermal sensors in the exhaust to kill the fuel flow when the ignition fails, but there are other problems with torque tube vibration that make driving in 4-cyl mode a risk.
Chris-- let me know how I can help you read the schematics. They aren't particularly easy to read, especially at first, but they will make sense after a few minutes of instruction I'm sure. We can do it over the phone to cut down on wear to the keyboards if you'd like.
The cat fire situation is pretty serious. The amount of time involved can be short or long, depending on the load on the engine and therefore the amount of fuel you are pushing into the cats.
It tends to affect the dual-distributor cars. The cars with dual coils have duplicate wiring and electrics for everything, so the car could be put in 4-cyl mode by anything from a coil to a coil wire to a distributor rotor or cap, also a failure of the ignition amplifier on the front apron. Chris suffered his problem when a coil wire was not properly reconnected after a TB change. Cambria had a similar problem and outcome.
So, if you have a S4 '87 or '88, or a pre-S4 car with two distributors (includes Euro US conversions with cats installed) and you feel the engine power drop, pull over and stop rather than trying to limp home in 4-cyl mode. '89 and newer cars have thermal sensors in the exhaust to kill the fuel flow when the ignition fails, but there are other problems with torque tube vibration that make driving in 4-cyl mode a risk.
Chris-- let me know how I can help you read the schematics. They aren't particularly easy to read, especially at first, but they will make sense after a few minutes of instruction I'm sure. We can do it over the phone to cut down on wear to the keyboards if you'd like.
Electron Wrangler
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From: Phoenix AZ
Rob,
R&R is worthwhile where you know of an issue - but there is just so much wiring to replace I can't see that replaceing it all is that much of a benefit for the huge amount of work involved. There is a serious risk that you break other things just in the process of getting in there to do it - connectors vacuum lines etc at least. I'd recommend you just focus on the problem areas and rework as needed - that probably still has a a net gain whether you use a factory harness or build your own.
Be aware that although the wiring diagrams tell you a lot they don't provide much help on exactly how the wires are routed and its quite a lot of work to even figure out everything that is combined into a given loom (they are spread out across multiple pages). Its also difficult to route wire as securely as the original factory wiring and so your replacements may not be as good as the original wiring if its still sound (and I think most of it should be).
I understand the wiring diagrams fairly well, and know exactly how many things are wired but I would not contemplate what you propose to do.
Alan
R&R is worthwhile where you know of an issue - but there is just so much wiring to replace I can't see that replaceing it all is that much of a benefit for the huge amount of work involved. There is a serious risk that you break other things just in the process of getting in there to do it - connectors vacuum lines etc at least. I'd recommend you just focus on the problem areas and rework as needed - that probably still has a a net gain whether you use a factory harness or build your own.
Be aware that although the wiring diagrams tell you a lot they don't provide much help on exactly how the wires are routed and its quite a lot of work to even figure out everything that is combined into a given loom (they are spread out across multiple pages). Its also difficult to route wire as securely as the original factory wiring and so your replacements may not be as good as the original wiring if its still sound (and I think most of it should be).
I understand the wiring diagrams fairly well, and know exactly how many things are wired but I would not contemplate what you propose to do.
Alan
Last edited by Alan; Sep 11, 2006 at 02:48 PM.
Burning Brakes
Joined: Jul 2005
Posts: 955
Likes: 2
From: Nashville x-burbs
Yes, it's the car from a dealer in Harrisburg, PA. The whole reason for the timing belt job was that someon (they?) had attached the a/c compressor wire to the tensioner gauge while replacing the belt and waterpump. The good news was that those parts are new.
The fire happened at idle, and the loom that appears burnt (so far?) runs to the box between the passenger seat and door. No one so far has been able to name this 'harness' or 'loom' so I am stuck asking parts dealers for a whole harness so far, which is too pricey.
I won't have time to think about the 928 until the weekend, but here's my number. The burnt fusebox wire we are trying to track is the top right red one from the blue 'Q' plug. It seems to loop back into the fusbox.
Thanks for your help and consideration. Without Rennlist I would never have purchased a 928, and it's evident that I could never maintain one without you guys.
Yes, leaving the passenger coil wire off was a costly, bonehead mistake... and it's costing me. Anybody want a parts car?
Chris
540-327-2730
The fire happened at idle, and the loom that appears burnt (so far?) runs to the box between the passenger seat and door. No one so far has been able to name this 'harness' or 'loom' so I am stuck asking parts dealers for a whole harness so far, which is too pricey.
I won't have time to think about the 928 until the weekend, but here's my number. The burnt fusebox wire we are trying to track is the top right red one from the blue 'Q' plug. It seems to loop back into the fusbox.
Thanks for your help and consideration. Without Rennlist I would never have purchased a 928, and it's evident that I could never maintain one without you guys.
Yes, leaving the passenger coil wire off was a costly, bonehead mistake... and it's costing me. Anybody want a parts car?
Chris
540-327-2730
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Thread Starter
Racer
Joined: Apr 2002
Posts: 424
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From: Denver Colorado
Hi Chris,
Wow, I started this thread over two years ago and just got my car back on the road the end of June.
As I recall there are two harness that go to the PS between the seat and the door. Their are two boxes at that location, one is the cooling fan control and the otheris the radio amp. I would suspect the harness that got fried is the dash harness. The dash arness connects to the electrics panel with four or five multi pin connectors. I would disconnect these connectors from te panel, make sure you unlock the connectors first. There is a white lever at the bottom of the panel and this needs to be pulled forward or to the rear of the car. Very very very carfully remove the harness cover the whole lenght of the harness and inspect the wires. You will probably find wires fused togeather, repair as required. Disconnect as little as possible and label what you disconnect. I bought a dash harness which I didn't use should you need one. Good luck.
Terry
Wow, I started this thread over two years ago and just got my car back on the road the end of June.
As I recall there are two harness that go to the PS between the seat and the door. Their are two boxes at that location, one is the cooling fan control and the otheris the radio amp. I would suspect the harness that got fried is the dash harness. The dash arness connects to the electrics panel with four or five multi pin connectors. I would disconnect these connectors from te panel, make sure you unlock the connectors first. There is a white lever at the bottom of the panel and this needs to be pulled forward or to the rear of the car. Very very very carfully remove the harness cover the whole lenght of the harness and inspect the wires. You will probably find wires fused togeather, repair as required. Disconnect as little as possible and label what you disconnect. I bought a dash harness which I didn't use should you need one. Good luck.
Terry
Burning Brakes
Joined: Jul 2005
Posts: 955
Likes: 2
From: Nashville x-burbs
I'm glad to hear you are back on the road.
How much do you want for the dash harness?
The budle of wires from the passenger side is burnt all the way up to the fusebox, and possibly up under the dash.
A mechanic came by Saturday who now thinks that he cannot fix it because instructions are, "not as easy as working on a BMW." Worse; he has pulled all of the plugs out of the fusebox, and I don't think he marked where they came from. I hope each plug is labeled by Porsche!
How much do you want for the dash harness?
The budle of wires from the passenger side is burnt all the way up to the fusebox, and possibly up under the dash.
A mechanic came by Saturday who now thinks that he cannot fix it because instructions are, "not as easy as working on a BMW." Worse; he has pulled all of the plugs out of the fusebox, and I don't think he marked where they came from. I hope each plug is labeled by Porsche!
Thread Starter
Racer
Joined: Apr 2002
Posts: 424
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From: Denver Colorado
Chris,
The wiring harness that I bought needed some minor repaire but otherwise in good shape and it came from a 87 S4. I think I paid $150 for it but would take less so make me a offer. My email address is n52923@msn.com
The wiring harness that I bought needed some minor repaire but otherwise in good shape and it came from a 87 S4. I think I paid $150 for it but would take less so make me a offer. My email address is n52923@msn.com
Instructor
Joined: Aug 2006
Posts: 142
Likes: 12
From: SF Bay Area, CA
Parts car for $1000 (SF Bay Area)
For anyone who still needs a wiring harness, parts car for $1000 -- Located in California, though.
No connection to seller (in fact, I've got dibs on the driver's & passenger's side door glass, if it's bronze and not green).
http://sfbay.craigslist.org/eby/pts/205940394.html
Damn shame what he did with the paint...
Dr. Bob: Thanks for the info -- I'm surprised they didn't do the monitoring electronically (like a mini timing light on both distributors -- But it is not for me to judge the wisdom of the Porsche gods). When the post-'89 system detects a fault, does it give an indication? Does the '!' light go on, or is there an indicator light that says 'Engine on fire!' or something? What does that translate to in German? Between that and the interference engine, the '87 &'88 guys must be walking on eggshells every time they start up their engine.
Does anyone think there's a market for a little electronic kit that would monitor spark and kill the engine if there is no spark for ~5 seconds?
No connection to seller (in fact, I've got dibs on the driver's & passenger's side door glass, if it's bronze and not green).
http://sfbay.craigslist.org/eby/pts/205940394.html
Damn shame what he did with the paint...
Dr. Bob: Thanks for the info -- I'm surprised they didn't do the monitoring electronically (like a mini timing light on both distributors -- But it is not for me to judge the wisdom of the Porsche gods). When the post-'89 system detects a fault, does it give an indication? Does the '!' light go on, or is there an indicator light that says 'Engine on fire!' or something? What does that translate to in German? Between that and the interference engine, the '87 &'88 guys must be walking on eggshells every time they start up their engine.
Does anyone think there's a market for a little electronic kit that would monitor spark and kill the engine if there is no spark for ~5 seconds?
Last edited by Foz; Sep 12, 2006 at 01:51 AM.
Burning Brakes
Joined: Jul 2005
Posts: 955
Likes: 2
From: Nashville x-burbs
Foz,
There is definitely a market for the kit you describe at the right price. People tend to want to pay very little for insurance like that.
That said, if it is under $30 I think every pre-89 928 owner would one if posted by a credible eBay seller.
There is definitely a market for the kit you describe at the right price. People tend to want to pay very little for insurance like that.
That said, if it is under $30 I think every pre-89 928 owner would one if posted by a credible eBay seller.
