Another public display of my ignorance: My 1990 S4 lacks a light under its hood. I don't believe that installing/omitting the light was an option, so I assume a prior owner removed it for some reason. I cannot see any wires, so I also assume replacing the light will involve running the wire, too.

From searching the forum, I've learned that earlier cars, including S4s (?) use a mercury switch to turn on/off the light. The switch also turns off the electric fans when the hood is open (an important safety feature). Do 1990 S4s have this style switch or had Porsche already started using the newer (GTS) style switch? Do I need to replace the lamp to obtain the turn-off-the-electric-fans feature? I carry a flashlight, so the light, while desirable, is not essential. Having the fans come on while I'm checking the oil is something I'd like to avoid.

Finally, I can call Roger, et al, for parts, but any ideas you all might have for sources would be greatly appreciated. Particularly, a parts list. It appears that I'll have to replace everything and don't even know where the original connections (below the hood) were made.

 

The newer style under the hood light is as of '91, so you have to get the older style, the mercury switch. It is a simple fixture and switch in one. Add a 10W bulb . The fixture is attached to the hood with a sheet metal screw, passenger side, about midway. You may find the hole for the screw is already there. Two wires to the switch, they run inside the outside of the hood. I would see if 928Intl has a good used one.

I might be mistaken, but I think the hood switch triggers the fans to stop instead of the under the hood light switch.

 

I have what you need if you don't mind slightly used. Email me if I can help.

 

The stock lampholder is a real POS both functionally and aesthetically - you may want to find something rather nicer and go LED bulb here.

The mercury switch only controls the lamp, it is not related to the alarm or the fan interlock which use the regular switch near the engine cross brace pass side. You may just want to use that switch for all 3 just like the later versions do.

Porsche discontinued this to reduce mercury content (env't regs).

Alan

 

I have all the wiring, etc for the 91 and up hood light, too.

 

So what's this? http://www.ebay.com/itm/PORSCHE-928-87-TO-95-LIGHT-UNDER-THE-HOOD-BRAND-NEW-WITH-LED-BULB-/390759904489?pt=Motors_Car_Truck_Parts_Accessories&hash=item5afb1af4e9&v xp=mtr
Mine doesn't look anything like this in my '87 S4.

 

Looks like the newer fixture used as of '91 with a led.

 

The placement of the light pre-91 is near the mercury switch. 91 and above it it is the center of the hood. Here's what I have on the '91. There's black cover not included on the eBay item.

 

Kevin has all the parts, so If you wanted the later stock look you could use that - however I still think even that one is pretty rubbish too...

Alan

 

Thanks to everyone for their comments. I appreciate the advice.

 

The mercury switch versions are connected to the license plate lights, the later version via the switch is not dependant on the lights being on (actually probably mainly a bad thing) and is powered by the alarm fuse.

Alan

 

The earlier bulb holder 928 632 105 01 is NLA as already said by Alan

The later setup is ---
928 632 111 01 Hood Light = $9.83
928 632 112 00 Cover = $2.77
928 632 113 00 Cap = $3.03

You will need the harness if yours was removed. Also add a nice switch so you can turn it on and off when the hood is up at shows.

 

http://www.ebay.com/itm/PORSCHE-928-...em5afb1af4e9&v xp=mtr

Always amazes me what people will pay on eBay - $16.95 for a part that costs $9.83 from Porsche. Must be a very expensive LED bulb 8>)

 

Yes - I agree this is a great idea, you will find that the hood is open in daylight far more often than in moonlight, so you mostly don't need/want the light...

Alan

 

" ... powered by the alarm fuse" .... aha, maybe that's why my light has never worked, my alarm is disconnected. Way down on my list of things to do but interesting possible explanation ...