Need help! Trunk light issue,

[Gonçalo]

Hello!
I have a 1984 porsche 944 and i have noticed 2 electrical problems. The door windows and the trunk light.
But I will ask for help for the Trunk light issue first.

So the trunk light isn't working as it should , it is working the same way the interior light is, when i open a door (driver or passenger)

[jcommin]

Yes it should. There is a switch on the light just as the dome light.

[pfarah]

Make sure that the connections on both ends of the passenger side rear hatch strut are secure. 12VDC runs through this strut which powers the light when the hatch is opened.

[CHICKS]

You can bend the little tang on the passenger hatch strut to contact the strut when it's open.

[jcommin]

You also need to insure the struts are orientated correctly. It makes a big difference.

[fiily]

Orientation of rear passenger strut to light up when hatch is opened.

[Gonçalo]

The passenger side hatch strut is just like you guys told , but doesn't make any difference because the light is working like the dome light, the dome light lights up when doors are open and the trunk light should light up only when the trunk is opened right? Or is it normal to work the same way the dome light is?

[Gonçalo]

If you prefer I can record a video of what's happening and leave you the link for you to see

[fiily]

So, if your asking if the hatch is opened, should it illuminate the hatch light and the dome light?

That woul be a yes and vice versa, the dome/hatch lights illuminates when the hatch is opened and/or when either door is opened..

[Gonçalo]

ohh! . I thought that they were associated to each thing .. the hatch to the back light and the doors to the dome light..
so if I get the Hatch strut working to light up the hatch when opened the dome light will also light up right? even if doors are closed.

[Gonçalo]

Correct me if im wrong but in some cars it works like I was thinking right?

[fiily]

Originally Posted by Gonçalo

ohh! . I thought that they were associated to each thing .. the hatch to the back light and the doors to the dome light..
so if I get the Hatch strut working to light up the hatch when opened the dome light will also light up right? even if doors are closed.

Right.

Hatch open = dome and hatch light on even if doors are closed
Any door open = dome and hatch light on even if hatch is closed



The above should be the standard way things light up in the porsche, unless you turn off the dome light via the switch on it

[Gonçalo]

Thank you very much for clarifying me! Now I'll try to fix the hatch strut problem. Which should be no big deal.

The other problem I have is that the windows only work if one or both doors are open, they don't move if the doors are closed, what can be wrong?

[fiily]

Originally Posted by Gonçalo

Thank you very much for clarifying me! Now I'll try to fix the hatch strut problem. Which should be no big deal.

The other problem I have is that the windows only work if one or both doors are open, they don't move if the doors are closed, what can be wrong?

Is the key turned to accessory, or position 2 in the ignition? I am going to take a wild guess and say yes, but just asking to point out the obvious first.

[DannoXYZ]

Is there a switch that detects when the hatch is open?

[jpk]

The dome light circuit in early cars is very simple; Each light gets constant power. The switch on the light controls how the ground (earth) connection is made.
In position 1, it makes a direct connection and the light is on (constantly). This is independent in each light (you can turn on either the dome light or the hatch light individually).
In position 2 (center) no ground connection is made and the light is always off (even if a door/hatch is opened)
In position 3, the ground connection can be made at any of three spots: either door switch or the passenger side strut. If any of those three switches are closed the ground connection is made and the light illuminates. If both lights are set to position 3, they will both illuminate.
The switch in the right side rear strut is simply a brass leaf that makes contact with the steel rod to complete the ground when the hatch is opened. When the hatch is closed, the leaf gets pushed up onto a plastic sleeve in the cup at the end of the strut and the connection is broken (and the light turns off).
The door pins work in a similar way; when the door is opened, the pin is pushed out via a spring, and contact is made to close the ground. When the pin gets pushed in, the ground connection is broken and the light goes out.
On 968's and maybe some of the later 944's (S2 perhaps?) they added a delay module into the ground circuit to keep the light on for a few seconds after the door was closed.

[BoulderGeek]

Thank you very much for this detailed explanation, @jpk! This is very helpful to me.

It might be telling em that my door switch is constantly grounded. Even though it does seem to work for the door open/key in ignition buzzer.

My dome light and hatch light are permanently on. In position 3, it is the same as position 1. With the exception of the hatch light, in that it smokes and crackles burning insulation when on.... :-(

I guess I need to test my door switches to see if they are feeding bad info about their state. I would like the interior lights to work automatically on all door or hatch opens. I hope to tie LED footwell lights into this.

[Gonçalo]

Thank you very much for the explanation @jpk! It was clear and helpful

[Gonçalo]

Originally Posted by fiily

Is the key turned to accessory, or position 2 in the ignition? I am going to take a wild guess and say yes, but just asking to point out the obvious first.

That happens in Position 2 or with the engine running..

[Gonçalo]

https://youtu.be/GjoojLABxNE
So here's a video to show you guys what's happening, sorry for any language mistake since English is not my native language, did my best.. If you don't understand something feel absolutely free to ask!