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Man of Leisure
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911SC Stays On After Key Switched Off - Please Help!
Hi All, hunting down a mystery electrical problem. Want to see if anyone has experience or advice on the following:
Car: 81 911SC. Super reliable other than electrical problems. AC and cruise removed. Lights, windows work. Fog lights, sunroof, and fan (in smugglers box) do not. No weird stereo or alarm wiring. Probably just the car showing it's well lived 40 years. Problem: Key on, car starts right up and runs fine. Key off, key comes out but engine stays running. If the engine shuts off, oxs and battery lights stay on dimly. What I've done so far: re-seated all fuses, pulled the electrical connections from the ignition (both the big and small plugs). Does not help, so the issue is not the ignition switch. Other info: car has run awesome for years, but a lot of the electrical didn't work when I got it. Since this was an autox/DE car, I didn't mind since I never used it. I recently was trying to get the fog lights working by reconnecting. The switch is getting power (as evidenced by the backlighting). When I pulled the switch, the backlighting went away but came back when I pulled the defroster switch. This is when the problem with shutoff began. I am thinking headlight, defroster, or fog light switch has a short that keeps power to the ignition circuit via the accessory lighting. But that is pure speculation. The only thing I know is with both plugs disconnected from the ignition switch, this is still happening. Oh, the problem is intermittent. If I disconnect the negative terminal on the battery, I can power on and off by connecting the terminal until the circuit is open again. Thanks in advance!
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Current: 81 911SC, 14 Boxster S, 08 Mini Cooper Clubman S, 13 Mercedes GL550 Former: 67 912, 69 912, 70 911E Targa, 70 914, 82 911SC, 85 Carrera, 90 Carrera 2, 02 Carrera "Game knows game" - Ice-T |
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08-18-2021, 11:10 AM
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Registered
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It's the actual ignition switch , behind the key
Ian
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Kermit, 73 RS clone, Just Part of the Team Chris Leydon ,Louis Baldwin ,Peter Brock ,Riche Clark Jerry Sherman ,Rob McGlade ,Donnie Deal Hank Clarkson ,Craig Waldner ,Don Kean ,Leroy Axel Gains |
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08-18-2021, 12:00 PM
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Registered
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Another way to get power to T15 with the ignition switch out of the picture is from D+ (T61) from the alternator through the charge light or the mileage counter relay.
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1974 Targa 3.6, 2001 C4 (sold), 2019 GT3RS, 2000 ML430 I repair/rebuild Bosch CDI Boxes and Porsche Motronic DMEs Porsche "Hammer" or Porsche PST2, PIWIS III - I can help!! How about a NoBadDays DualChip for 964 or '95 993 |
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08-18-2021, 12:54 PM
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Man of Leisure
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Thanks for the info! I was trying to take a video to post and the problem went away. Tracking with a voltmeter, we traced a lot of relay problems so I think this was a sticky mileage counter relay.
The good news is now the fog lights and sunroof motors work as well after I reseated and replaced bad relays.
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Current: 81 911SC, 14 Boxster S, 08 Mini Cooper Clubman S, 13 Mercedes GL550 Former: 67 912, 69 912, 70 911E Targa, 70 914, 82 911SC, 85 Carrera, 90 Carrera 2, 02 Carrera "Game knows game" - Ice-T |
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08-23-2021, 04:09 PM
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Retro Porsche
1974 Porsche 911 Targa 3.6
