Headlights refuse to retract, 1974 car with headlights that refuse to retract Options

[Jezibel]

Main lighting switch raises lamps, lights up, but pushing switch back in fails to lower the lights.

AI says 1) Check fuses for failed or faulty fuse; 2) check headlight relay on fuse-box backside; 3) check grounds; 4) check headlights switch for possible corrosion on contacts.

System was working fine last week. It just decided today to not lower the lamps.

I have a replacement main lighting switch on order, also several Bosch 5-pin relays, and all the fuses check out OK (no corrosion on fuse block contacts.

I lowered the headlights manually, using the motor-end knobs, per the protocol, but it irritates me to not be able to immediately fix this apparently quite common problem on my '74 1.8 liter.

Any helpful suggestions, other than the cited "4-most likely causes' AI pointed out, above?

Thanks in advance.

[emerygt350]

Main lighting switch raises lamps, lights up, but pushing switch back in fails to lower the lights.

AI says 1) Check fuses for failed or faulty fuse; 2) check headlight relay on fuse-box backside; 3) check grounds; 4) check headlights switch for possible corrosion on contacts.

System was working fine last week. It just decided today to not lower the lamps.

I have a replacement main lighting switch on order, also several Bosch 5-pin relays, and all the fuses check out OK (no corrosion on fuse block contacts.

I lowered the headlights manually, using the motor-end knobs, per the protocol, but it irritates me to not be able to immediately fix this apparently quite common problem on my '74 1.8 liter.

Any helpful suggestions, other than the cited "4-most likely causes' AI pointed out, above?

Thanks in advance.

Did you check the relays on the headlamp assemblies in the frunk?

[Jezibel]

No, I did not. Where are they located in the frunk? The only relays I am familiar with are those on the underside of the fuse panel. Thanks.

[Jezibel]

No, I did not. Where are they located in the frunk? The only relays I am familiar with are those on the underside of the fuse panel. Thanks.

Below iz what AI sez:

What's NOT in the frunk: The main dimmer/combination relay (which switches the headlights on/high-low beam) lives under the dash, on the back side of the fuse panel — right where you've been working, not up front. So the core headlight power circuit is a dash-area relay, not a frunk relay.

What IS in the frunk (near each headlight): The 914's pop-up headlight doors each have their own dedicated headlight motor control relay, and these are mounted up front near each headlight bucket/motor, not under the dash. Here's the logic: the dashboard switch doesn't drive the pop-up motors directly — it just sends "extend" and "retract" command signals up two wires to the front trunk area. At each headlight, a cam-operated switch on the motor mechanism reads the physical position of that headlight door and compares it to which command line is energized. If they disagree (say, switch says "up" but the headlight is still down), that local relay near the headlight motor energizes and runs the motor — pulling +12V through fuse S12 — until the door position matches the switch position, at which point the cam switch drops the relay out again.

So to directly answer it: yes, there are relays at the headlight assemblies themselves, but they're the motor-control relays for the pop-up doors, one per side. The relay that actually controls whether the headlight bulb is on, and whether it's high or low beam, is back at the dash-mounted fuse/relay panel you've already been dealing with.

This matters practically if you're troubleshooting: a "headlights won't pop up" complaint points you to the frunk relays near each motor, while a "headlights won't come on" or "stuck on high beam" complaint points you back to the dash-mounted combination relay behind that same fuse panel giving you access grief.

[Jezibel]

No, I did not. Where are they located in the frunk? The only relays I am familiar with are those on the underside of the fuse panel. Thanks.

Below iz what AI sez:

What's NOT in the frunk: The main dimmer/combination relay (which switches the headlights on/high-low beam) lives under the dash, on the back side of the fuse panel — right where you've been working, not up front. So the core headlight power circuit is a dash-area relay, not a frunk relay.

What IS in the frunk (near each headlight): The 914's pop-up headlight doors each have their own dedicated headlight motor control relay, and these are mounted up front near each headlight bucket/motor, not under the dash. Here's the logic: the dashboard switch doesn't drive the pop-up motors directly — it just sends "extend" and "retract" command signals up two wires to the front trunk area. At each headlight, a cam-operated switch on the motor mechanism reads the physical position of that headlight door and compares it to which command line is energized. If they disagree (say, switch says "up" but the headlight is still down), that local relay near the headlight motor energizes and runs the motor — pulling +12V through fuse S12 — until the door position matches the switch position, at which point the cam switch drops the relay out again.

So to directly answer it: yes, there are relays at the headlight assemblies themselves, but they're the motor-control relays for the pop-up doors, one per side. The relay that actually controls whether the headlight bulb is on, and whether it's high or low beam, is back at the dash-mounted fuse/relay panel you've already been dealing with.

This matters practically if you're troubleshooting: a "headlights won't pop up" complaint points you to the frunk relays near each motor, while a "headlights won't come on" or "stuck on high beam" complaint points you back to the dash-mounted combination relay behind that same fuse panel giving you access grief.

I guess that translates to "Yes, the headlight relays that are at the headlight locations in the Frunk DO need to be checked and presumably, they are under the black plastic covers lateral side of each headlamp motor, eh? My main lighting switch raises the lamps and switches the lights on just fine; it's getting them to retract again that is the problem, QED.

[L-Jet914]

The relays for each headlight motor is mounted underneath the plastic covers below each headlight motor. See image for location which I pulled from another thread here on 914World. Take what AI says with a grain of salt as it's not always correct. It's be to browse the forums here for answers to your questions. Bosch 5 pin relays will not fit in the locations of where the factory round relays reside without modifications to the factory wiring harness. You can still get the 5 pin round relays new from multiple vendors. Also attached is the under dash relay board layout from Jeff Bowlsby.

(IMG:http://bowlsby.net/914/Classic/zTN_Elect_Relays_MainFusepanel.jpg)

[cgnj]

@Jezibel
Here is a link to PP headlight troubleshooting methodology. Good luck.

PP headlight troubleshooting

[Cairo94507]

Buy a couple of new headlight relays and swap them in. They do go bad. I had new ones in my car when we built her about 7 years ago. Recently I had a headlight that would just go up and down when I turned the headlights on or off. Swapped in a new relay and problem solved. Nice to keep a spare too. (IMG:style_emoticons/default/beerchug.gif)

[fixer34]

This from the pelican article:

"The first step is to determine in which electrical system the problem is located. An important clue is whether both headlights are affected, or just one. If both headlights are affected, the fault is highly unlikely to be caused by a bad motor or a bad relay.... it most likely is in the part of the system common to both headlights."

If both headlights go up when the light switch is pulled out, but NEITHER go down when pushed back in, it is something in common such as a power feed.
The relays are independent and only drive one motor.

Need to get the multimeter or test lamp out and check the power circuits that run to both motors. I think the wiring diagram notes them as GY and R (from fuse 12)
GR-BK to the relays could also be suspect.

[Jezibel]

This from the pelican article:

"The first step is to determine in which electrical system the problem is located. An important clue is whether both headlights are affected, or just one. If both headlights are affected, the fault is highly unlikely to be caused by a bad motor or a bad relay.... it most likely is in the part of the system common to both headlights."

If both headlights go up when the light switch is pulled out, but NEITHER go down when pushed back in, it is something in common such as a power feed.
The relays are independent and only drive one motor.

Need to get the multimeter or test lamp out and check the power circuits that run to both motors. I think the wiring diagram notes them as GY and R (from fuse 12)
GR-BK to the relays could also be suspect.

Fixer34! Thanks for the help. I just got the car back from my Porsche service today (13 Aug 26) and they told me that the power feed to #30 on headlight switch was not attached to t6he proper terminal on the fuse board! Story is that a previous owner had run a power wire to the fuse board and taped it to the correct terminal, but that the wire had come detached from the#30. Hence no live juice to the main headlight switch. The switch itself and also the existing Combi-Relay were both fine...not problem whatsoever with them. So now I have THREE of the main headlight switches and 6 'Combi-relays'...all good and perfect as spares. The title of all this kerfuffle could be "MUCH ADO ABOUT NOTHING!" Embarrassing, to say the least -JEZIBEL. Thank again!