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Speed & Reference Wires Fraying [pics]

I noticed over the last year that I could not start my car after it was raining, or humid, or a drastic temperature change. This led me to looking at conditions of grounds and such. I eventually located the problem on either the speed or reference sensor harness. One of them, if jiggled, will alleviate the no-start, and the car is happy to run all day. However, once it cools down, and/or rains, the car is a no-start. Seriously, if I jiggle both sensor harnesses, the car starts right up.

Today, I pulled back the rubber boots from the harness and saw this (on the wiring harness-side of the connector, not the sensor side):





There's 3 wire connections on the harness but only 2 actual wires within the harness. Yellow, black, and a 3rd what looks like insulating/noise reducing mesh of wire that surrounds both other wires (filling the inside of the grey large wire) and connects to one of the 3 pins. Both sensor harnesses have this. However, as you can see in the 2nd pic, the mesh is exposed much much more than the other harness, and also (you can't see it), the yellow wire has a small break in the insulation around its wire core too.

How would I go about fixing this? Do you think there's more to see inside the harness itself at the pins?

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Black 1986 944

Last edited by exitwound; 06-03-2010 at 04:18 PM..
Old 06-03-2010, 04:11 PM
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I would think, if you know how to replace the connectors, that it could be done. My main worry would be if there is enough slack to do this.
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Last edited by Tidybuoy; 06-03-2010 at 08:38 PM..
Old 06-03-2010, 04:38 PM
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Exitwound,
Great pictures as usual.

If you look at the Clark's information on reference sensors and go to the pin munbers--
Speed and Reference Sensors - Checking, Replacement, and Adjustment

Number 25 & 8 use the black wire
Number 26 & 27 use the yellow wire
Number 78 & 23 use the blue-sheilding wire.

Here is a closeup of a bad connector and the OEM Bosch.



TexasBlake did a good DIY
Harness Repair- Porsche 951 - www.texasblake.com

Parts
Bosch, Amp, & Weatherpack Connectors

Another parts company:
Eagle Day , PORSCHE, BMW, APPAREL, ACCESSORIES, PERFORMANCE, MEMORABILIA is EagleDay

GL
John
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Old 06-03-2010, 05:02 PM
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Thanks for all the info.

I'm not sure how I'm going to be able to 'fix' that 3rd mesh wire though. If it's all frayed because it's insulation around the other two wires, how am I going to be able to cut and splice in a new harness?
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Old 06-05-2010, 07:05 AM
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They ain't frayed......their scared to death!
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Old 06-05-2010, 09:48 AM
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Easy fix

I had dead wires on my 951 reference sensors as well.
Same symptoms for a couple of years.

Go to Lindsey Racing. They sell a harness that just replaces the sensor wires to the DME. Took me about 3 hours and she fired up on the first turn!

Also advise replacing the sensors themselves. I found new ones strsight from Bosch factory on ebay brand new for about 60 bucks each.
Old 06-07-2010, 10:16 AM
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Wow $100 is a big difference from the $10 to build my own. The wiring also runs underneath the intake (which isn't a pain to take off after doing it so much!) but also through the firewall. How much of a hassle is this? Seems like a lot more work than rebuilding the harnesses themselves.

Hmmm, I don't know if I wanna get into this heh.
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Old 06-07-2010, 03:28 PM
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Don't even think about removing the old wiring, just snip them off.
The new harness is an easy feed through the firewall. Then you just zip tie it to the harness.
There are complete instructions online at Lindseyracing.com (these guys are good)
They also have a harness replacement for the fuel injectors which I am putting in next week.
Old 06-08-2010, 05:34 AM
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Making the right connectins

Trailer connectors.
Three or four pin. Heavy duty. Available anywhere. Cheap and comes with extra heavy gage wiring. Solder and shrink wrap wiring. Once around the connector with tape to seal. Done. Nuff said.
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix.
Old 06-08-2010, 12:46 PM
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Best of luck with that method. Don't forget the duct tape! Nuff said!
Old 06-08-2010, 01:34 PM
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out of luck

Don't need luck. Over a year and approx 15K miles on the DD since the mod. Electrons really don't care whether a connector is OEM or not. So...Why should I?
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix.
Old 06-08-2010, 07:43 PM
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Hey Patrick:

I know the pain! Had a car in to work on that had the exact same problem.

What I ended up doing is buying two connectors, new, from ***********.com. Cost was around three/four bucks, plus shipping.
Then, I carefully removed some of the harness PVC with a razor blade. I then re-wrapped each one of the three (3) wires with electrical tape and sealed it with some of that "Electrical tape in a can" stuff.

Hope this helps and good luck.
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Old 06-08-2010, 10:26 PM
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Patrick:

I forgot to mention this earlier:

***********.com sent me the connectors and they had about four (4) inches of wiring attached already which made things easy. Just so you know.
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Old 06-08-2010, 10:28 PM
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I didn't realize *********** sold these. I'll have to look into them.

thank's for the various methods by which to attack this. I realize that Lindsey's new cables are the BEST fix, but for the cost, I don't know if I can justify it. For a few $$ for either of the other methods, it's worth a shot. I mean, the worst it can happen is that there's a permanent no-start...which, I guess would be pretty bad. But that's the outcome if I do nothing anyway as the resistance builds in the harnesses as time goes by.
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Old 06-09-2010, 04:11 AM
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connectivity

yes, there are many options. As long as you get a good connection things will be well. Anything other than the old brittle connectors will be an improvement. You could even soldier the wires together and not have a connector at all.

Resistance builds in the harness? Are you talking about harness degradation or connection problems?
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix.
Old 06-09-2010, 07:23 PM
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I'm obviously dealing with some sort of resistance issue inside the harness. It's much more pronounced after it rains, when the temperature changes, etc. I'm seeing higher resistance in the wires as a result. Note, I haven't measured the resistance with a meter yet. I don't believe it's purely a 'bad connection', as in a broken wire. I think it's a combination of the old harness along with some corrosion or just lack of integrity in the wire that shows during weather-related events.
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Old 06-12-2010, 12:23 PM
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internal connections

Well, I haven't taken the harness back as to the sped and ref sensors. However I can say that the injector wiring has crimp connectors that corrode and degrade with time and I did notice that the injectors started going bad in the damp before they finally went belly up. Perhaps there are some similar connectors along the sensor circuit. A meter might not be giving you the whole story as it tests resistance with a very small voltage and so you may need to go into the harness to trace the wires (ugh). First be sure that you have a good connection to the sensors and then go from there.
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There may be nothing quite as expensive as a cheap Porsche: Ruby Red 84 928S : White 87 924s 2.5L NA (Blinky) M44/07-43H10676 spoiler delete - 046/2B - Belts 9/12, Clutch and OC seals 8/08 andd Red 94 Del Sol: Please put your Make, Model and Year in Sig. Try not to break more than you fix.
Old 06-13-2010, 08:24 AM
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This thread and effort of the group was very helpful and I am grateful for you all's time and advice.

Eagleday.com does not currently carry the 3-pin male adapter. I checked ebay and ordered some, but also ordered a set of "Bosch Style (Amp Junior Power Timer) 3 pin connector" kits (one male one female). From efiexpress.com Efi Express. ($32 incl shipping)
They arrived quickly, but I was nervous about cutting into the leads, thinking, if I screw this up, I may end up having to drop the transmission, given my skills.

As others have noted, the male side of the coupler (flywheel side) had disintegrated, the female side was in tact. Using channel locks, I dissected the male side so only the leads with the ends still on them, were left. DO NOT CLIP THE OLD LEADS OFF THE WIRES. (order from front of car to back = 1) aluminum lead ground, 2) orange, 3) black)

*** THOSE LEADS CLICKED INTO THE NEW BOSCH PLUG *** Meaning there was no need to clip any wires. One thing, make sure you install the new rubber boot that comes with the new assembly before clicking the old leads into the new bosch male assembly.

I then started to dissect the female plug assembly. I found, with the hard plastic outer sleeve clipped away, that the new male plug fits into the old female plug !!! The car runs and I have quit while I am ahead. I used a few zip ties to secure the connection and left the old female plug in place for now.

Maybe this weekend I will dissect the female end and make the thing the way it is supposed to be. It is rare I find something working as well as it did this afternoon and wanted to add that 2 cents to the next person looking for an answer.

ps If I have made a mistake with the car, I probably would rather not know

Thank you all again, Alen
Old 03-09-2011, 08:28 PM
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This is good information.

Expensive but OEM.




Thanks & welcome.
John
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Old 03-09-2011, 08:41 PM
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I went to a junkyard one day and clipped about 5 or 6 connectors from various European cars (VWs, Volvos, Saabs, etc) and replaced my bad one with one of those. They didn't charge me a thing for them.

Old 03-10-2011, 06:05 PM
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