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Registered User
Join Date: Dec 2007
Location: Ireland
Posts: 71
danglerb or Alan

I don't want to keep asking questions from you on this topic but i just want to find out a few more things. I am going to test what you already suggested at the weekend as iv got someone to give me a hand. I'm also after getting a Manual so that should help me out although the Manual seems to provide most info on LH and Ezf for (87 up) 35pin ECU. info on the 25pin for an 86 would be useful.

Anyway what i need to know is regarding connection (W) 14 the two black wires here. Iv found this is where I'm having a problem with power staying on with ignition off. relay xvi provides power here when it switches at pin 87. But what I'm getting is also 12v on the connection end of these two wires. Basically if i disconnect W from the CE and turn the ignition to on iv 12v at these two wires, so if i plug it back in, pin 87 is energized and the relay wont switch off. could you explain if your car has 12v here too and or where I could be picking up 12v if there not ment to? I'm trying to trace them but they go out through the firewall and i cant find them after that. I know you said earlier that they go to pin 18 of LH brain and 25 of Ezf, but do they go out to the engine bay somewhere first as I could see if they went straight to the two ECU`S?

Also, I was thinking back to when the car wouldn't start anymore. it was after this problem so the two may not be linked . she would start but would idle poorly and when I would put it in reverse she would cut out sometimes. it seemed to have this erratic idle from day one but drove OK other then this but bare in mind I only had it a few days. Could this suggest anything or was it just a bad idle control or vacuum as i thought at the time? I'm going to do my homework and get ready to tackle it this weekend so any extra info would help. thanks for staying with me on this one guys.
Old 04-21-2008, 02:10 PM
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Network Native
Danglerb's Avatar
Join Date: Jan 2007
Location: SoCal
Posts: 10,196
W14 is the power on signal from the central electric to the two brains, and I will take a wild guess the previous owner felt it a dandy (terrible) way to bypass some alarm etc. problem, essentially hot wiring the car. I don't see the W14 wires going far or anyplace else, so look for a splice right around the CE and brains.

Workshop manuals cover all previous years up to some model year (paper version) the CD from Jim Morehouse covers all years.
Old 04-21-2008, 07:43 PM
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928-Electrics Guy
Alan in AZ's Avatar
Join Date: Jun 2007
Location: Phoenix AZ
Posts: 710
Someone screwed with it... Here are some simple tips to help:

Porsche used colors for functions quite religiously (here are some highlights)

Plain Brown - Always ground
Plain Red - Unswitched battery
Plain Black - Ignition Switched
Black/Yellow - Accessory Switched

Brown/White - Switched ground
Red/White - Switched Battery+

Any black wires should be active only with ignition on. These 2 are the feed from the reay to the ECU's thats the only connections that should be there - check for a wire snaked into an ECU connector...

As Danglerb says check for any extra connections - you may need to check on the back of the panel - take it out.

I think you should note any non-stock wiring on the back of the CE panel - non-stock is anything spliced anywhere on the wiring on the back of the panel. Figure out what its connected to and where it goes... Someone who had no clue messed with it... you may need to undo other things. In general almost nobody understands the electrical system of these cars - so when you find evidence of tampering be very worried and take appropriate action....

1994 928 GTS Black/Black Manual
Old 04-22-2008, 01:30 AM
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Registered User
Join Date: Dec 2007
Location: Ireland
Posts: 71
yes iv taken a look at the back of the panel of the CE. someone has been at it before me and in going to go through it and see what I find.

just to get one thing straight. I shouldnt have power on the W 14 connection when i disconnect it from the panel and turn the ignition switch to on and check with voltmeter? I should only have power supplied from pin 87 when the relay switches to W14 which gives the signal to the brains?

also how would they have gone about bypassing the alarm. have you any idea? these two black wires im sure go out through the firewall as well as every other wire on W. I will have to take a closer look and see what wires have been spliced over the weekend.
Old 04-22-2008, 02:57 PM
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