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Warning Circuit


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After some troubleshooting on the wiring side, I am trying to determine the wiring location to the seat belt connector for driver's seat. I have located the two pin male connector on the seat belt receptacle, but no wiring beyond that through the tunnel, nor to what I can determine the clock / emergency warning circuit to be. The clock works fine. As a secondary question, does the brake warning link to the parking brake or only the brake pad wear circuit, as it goes out one the engine is running with the parking brake engaged or not.



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What year is your vehicle? The park brake warning and the brake circuit failure are one and the same. If the park brake warning light goes out with the engine running I can only guess someone had the gauges out and connected the wiring wrong or the bulb sockets.

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What year is your vehicle? The park brake warning and the brake circuit failure are one and the same. If the park brake warning light goes out with the engine running I can only guess someone had the gauges out and connected the wiring wrong or the bulb sockets.

It's a 1984. Which connection do you think is wrong? Back of the warning circuit board or somewhere else perhaps?


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People often remove the gauges and incorrectly re-install the wiring. You need to locate a wiring diagram to verify the connector locations.

Thanks - will do that this weekend then.

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  • 4 weeks later...

Managed to get the light to go out finally by changing the door switch on the driver's side and did further troubleshooting to determine where the seat belt wiring was.

Dug through the dashboard to find the warning relay behind the left gauges and using the Bentley manual determined the following connections should exist from the relay: 15 (red/blk wire instrument cluster), 85 (vio wire to buzzer switch), 86 (brn / wh wire to both door switches and seat belt connector), G (gry / red wire to seat belt connector), L (grn / yel wire to warning light - seat belt side) and 31 (brn wire to ground) only actually has 15, L and 31 wires connected and available.

1. 85 - no wire to the buzzer switch, although it seems to have the two connections beside the ignition switch;

2. 86 - no brn / wh wires to door switches nor seat belt connection although the door switches turn the dome light on and off as appropriate; and

3. G - no gry / red wire to the seat belt contact.

Also, the relay is a 911-618-102-01 actually doesn't have the 85, 86 or G connectors (nor are they on the harness side), although when I look up the parts manual the car should have a 911-618-102-00 which has these connection. The car is an ROW, but according to PET 7.1 with my VIN, it should have the second connector.

Also, the parking brake light doesn't come on even after cleaning the contacts and confirming continuity between the warning light and the brake connector.

Have put together the diagram as best I can figure and am attaching it - hopefully it makes sense to someone.

post-49895-029998600 1276476079_thumb.jp

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ROW cars don´t have the Key buzzer and therefore miss that litte switch in the steering lock and also have a ROW Wireloom wihhout buzzer. Not sure about sweden/norweagan as they also have the seat belt lock light mandatory but ROW came without seatbelt lock light.

The fasten seatbelt in ROW goes on when you turn the ignition key and goes of after engine runs in several secounds. The timer is set by the idiot light from the alternator

Sweden/Norway and late Switzerland have the Seatbelt function from the US cars so you will find the seat occupationswitch and the contact switch from the beltlock.

The Brake warning light has a Nand/Nor logig gater and operates for the brake fluid sensor,differential pressure, the brake pad sensors and the parkbrake. There is single idiot light and doubel idiot light version with integratet warning buzzer.

The Parking brake switch is itegratet in the rear from the handle so to check that you have to remove the heating unit and loose the Prking brake handle much simpler is to remove the heating unit tehn losse the adjustment screw on the switch and move the switch until the light goes on/off. If it ain´t work you can look at the steel rivet who holds the cooper contact if it is lose the cooper contact might feel off. If not then remove the brake lever base lift the rear and check if the spadeconnector sits correct.

To work on the heating unit/brake lever it is the best to remove the passengerseat.

You also can check the wire to the switch for conntiunity and make a local ground to check if the Warning light works.


Edited by IXXI
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That makes so much sense - it is a RoW German vehicle and the relay only has three termainals vice the six for buzzer and seat belt warning connectors. I don't have access to the RoW electrical wiring diagrams as the Bentley Manual I have only gives US/CA options from what I can tell. Would those be available somewhere perhaps?

Vielen Dank. Tschüss.

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This is a 1988 Wireplan set; http://www.911c1.de/porsche/Schaltplaene/plaene1-10_carrera_32.pdf but not to usefull,,, be carefull the pre 85 3,2L main wireloom is still based on the SC wireloom has some other colors and a other 14 pin connector interface in the engine bay but the frontend and dash is very close to SC.

Still try to find a 84 ROW wireplan online. here in germany you can go to the next Porsche Dealer and lay down your Papers and the parts dep will order the correct wire shematic set to the VIN make sure they order the complete set with the additional sheets (84 ROW Coupe should have som 20 Pages just look over at Pelicans parts at the US SC wire shematic page).

The basic function from the Seatbeltremainderlight is just to burn after turning the ignition key.

The warning lights for the brakes should be split in two chambers on is for the fluidlevel and the differential pressure wich warns if one brake circuit fails. The other light is for the handbrakelever and for the brake pad warn contacts (if not tricked ot by previuos owener). Maybe the car still has the operators manual wich will explain the idiot lights.


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