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Porsche 928: Why Won't My Interior Lights Turn On/Off?

Interior light malfunction can be puzzling for a novice. This article outlines some flash points causing the interior lights to not work in a Porsche 928.

By James Karuga - April 16, 2015

This article applies to the Porsche 928 (1979-1995).

At night, the interior lights are vital when getting into the car and locating the ignition barrel or looking for anything in the car. The interior lights in a Porsche 928 are conditioned to turn on when the door or hatch is open and off when closed. If the light is bad, it won't turn on, and if the hatch's switch is bad, it would stay on after you've closed the hatch. Here's what to do if anything is wrong with your interior lights.

Step 1 – Is the hatch properly closed?

The interior light remains on if the hatch is not properly closed. If you notice the interior light of your 928 is on after all the doors are closed, then check if the hatch is properly secured. An open hatch causes the interior light to remain on and if undetected, a Porsche owner can go on a costly diagnostic spree, yet it's a simple issue. That is why if you notice the interior light on, check if the hatch is properly closed. If the light stays on, it could drain the battery. If the hatch fails to properly close due to a faulty release latch, investing in a new one for around $60 is viable.

Figure 1. Make sure the hatch is properly closed.

Step 2 – Is the hatch release switch working?

The hatch release switch is designed to turn on the interior light when the hatch is open. But if the interior light remains on after the hatch is closed, it could indicate the hatch release light switch is faulty. A faulty hatch release switch loses the grounding effect that turns off the interior light. If the hatch switch is broken, replacing it remains the plausible option. A new hatch release switch costs less than $30 for the 928. You can replace the hatch release switch yourself with instructions; it's not very challenging.

Figure 2. Check the hatch release switch.

Step 3 – Are the door contact switch wires okay?

Assuming the door contact switch is okay, there are instances where after the doors are open, the interior light fails to light up as required. That could be caused by blown fuses after casings of the switch wires peel off or corrode and end up touching the Porsche's ground parts. Ageing and adding other aftermarket components also overloads the circuit, causing the fuses to blow. Bad grounding in some doors also causes some door lights to remain on while the door is closed. Opening up the door contact switch helps you to see which wires have peeled off; replace them or cut off the peeled part, then connect the switch to the unpeeled wire parts.

Figure 3. Check the contact switch wires.

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