W124- Firewall pass through to engine bay?
 

I am hooking up my nitrous pressure gauge and air/fuel gauge and i cannot find a pass through in the firewall to route the wires (Its a 400e). I have the driver side bottom dash removed but i cannot find any holes. Also, does anybody know if the light source and power source for the cigarrete lighter are 12 volt sources?

Look for a possible point of passage through the firewall on the passenger side just behind main computer box. You will see many other wires running through the firewall at this point. I had a cell phone, hands free kit mounted with the wiring running through this area.

Yes, 12 volt.

124 passthrough
 

On my '87 300D 124 there is a rubber manifold that passes vacume lines to the dash. It has several unused ports that can be pierced and used to gain access to the interior of cabin. Must remove instrument cluster to view its backside, and work from there. I plumbed turbo boost gauge and 500E Euro headlight controls through the firewall using this route. Not sure if 400E is the same, but maybe.

how does the instrument cluster come out? Thanks for the replies

http://www.peachparts.com/shopforum/showthread.php?t=71691

Great DIY on dash removal