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I'm in the process of moving all of the console buttons to a radio delete panel. While I'm at it, I figured I would move the sunroof button as well. I was hoping to use a 993 Sunroof switch in the radio instead of the 964 one. However, the plug sizes are vastly different: the 964 button is very heavy duty with large connectors; the wiring to the button is much lower gauge (i.e. thicker) than the corresponding wiring for the 993. I can fabricate a plug end from the 964 wiring for a 993 button, but is it safe to use the 993 button? Are there low voltage concerns here given the smaller plugs on the 993 button?
If anything the 964 unit should be on its last legs, I wouldn't hesitate to use the newer
993 part, doubt there's any measurable difference in resistance...Bert
I would highly recommend not following the advice above. I'm not familiar with the sunroof circuit, but it will be pulling a fair amount of amps. My cabrio uses the same switch. The likely explanation for the beefy 964 vs the lighter 993 switch is that the 993 uses a relay on the circuit where the 964 does not. If that's the case, the 993 switch will get cooked. Worst case is a lot of melted wires. You can always add a relay to the circuit if needed.
The 964 wiring diagrams float around the net. I don't know how available the 993 diagrams are to find. Good luck!
I would highly recommend not following the advice above. I'm not familiar with the sunroof circuit, but it will be pulling a fair amount of amps. My cabrio uses the same switch. The likely explanation for the beefy 964 vs the lighter 993 switch is that the 993 uses a relay on the circuit where the 964 does not. If that's the case, the 993 switch will get cooked. Worst case is a lot of melted wires. You can always add a relay to the circuit if needed.
The 964 wiring diagrams float around the net. I don't know how available the 993 diagrams are to find. Good luck!
Thanks Nick. I have used the same thickness 964 wiring to extend the original 964 wires to the center console; I would be soldering those wires directly to the (smaller) 993 plugs to fabricate the 993-compatible plug. I've disassembled the 993 switch, there is no wiring present in the switch. So my only concern here is the switch itself. Given the thicker wiring, is cooking the 993 switch still a concern?
The amp rating of the switch would be the concern. If it shorts internally then the wires can cook pretty quickly.
Check the wiring diagrams. If the 964 and 993 circuits are the same, then you're fine. If they're different, then figure out how and why before installing the smaller switch.
I'm not sure if this helps but the Sunroof for the 964 uses a "Bridged" Relay (R21) that connects to pin 1 on the switch. Pins 2 and 4 on the switch go to the motor.
Bumping a (kinda) old thread in search of additional info.
Josh did you ever end up using the 993 switch successfully?
No, I did not. The 993 uses a separate relay for the sunroof. After disassembling the switches and comparing the internals, I believe that the 993 switch will not be able to handle the electrical requirements of the 964 sunroof. I ended up ordering a new 964 sunroof switch and mounting in the radio delete panel.
04-10-2017, 06:52 PM
Use 993 Sunroof Switch in 964?
