Rear Window Motor Upgrade

[TG-2002-320i-328ci]

Hello All

I spent the weekend cleaning and upgrading my rear windows (73 CSi) to run on E28 motors.

A couple of years ago, I used this step-by-step process for the Front windows. I kept the old wiring system and did not add a relay system - just grounded the two front switches on the unused post connector on each switch as per the drawing below.

Now that I am doing the rear motors, the question is this: do I have to ground both the front and rear switches or just the rear?

Thanks as always.

Restoration of a 1972 BMW 3.0CS - Window Motor Conversion - Part 2

Modifying the Wiring Modifying the wiring to allow the existing switch to be used with the new 2 wire motor is actually much easier than you might expect. Essentially you need to provide a ground to the free connector on the drivers window switch, and you connect the blue and the green wires from

sites.google.com

 

[jmackro]

Yes, with the 2-wire motors won't function unless the motor can be connected to ground through whichever switch is actuating it. Just don't ever have the front switch in the UP position with the rear in the DOWN !

 

[Stevehose]

Are you going to relay them?

 

[TG-2002-320i-328ci]

Yes, with the 2-wire motors won't function unless the motor can be connected to ground through whichever switch is actuating it. Just don't ever have the front switch in the UP position with the rear in the DOWN !

Got it.

I dread taking apart that front console again...

 

[TG-2002-320i-328ci]

Are you going to relay them?

I wasn't planning on it, but seeing as the car will be sitting for the next 3 months, perhaps I should.

Here is a thread that describes the process: https://e9coupe.com/forum/threads/a-few-tips-on-installing-e28-window-motors.27320/

 

[Thomas76]

The relays are cheap, it puts so much less load on the switches.

 

[TG-2002-320i-328ci]

The relays are cheap, it puts so much less load on the switches.

Is there a thorough thread describing the entire process of adding the relays?

Edited to add: before I changed out the front sardine cans, a bit of smoke from the front switches was not uncommon - so I do appreciate the load that they bear.

Thanks

 

[Stevehose]

Is there a thorough thread describing the entire process of adding the relays?

Edited to add: before I changed out the front sardine cans, a bit of smoke from the front switches was not uncommon - so I do appreciate the load that they bear.

Thanks

Electric window relay upgrade

Finished today a week-long project installing relays on each of the electric windows. I followed the postings of Jmackro and Jhjacobs. I hooked up a 12 gauge wire (30 amp fused - orange wire in the pic) to the battery: I had bought dual relay sockets and relays off eBay, removed the open...

e9coupe.com

 

[TG-2002-320i-328ci]

Electric window relay upgrade

Finished today a week-long project installing relays on each of the electric windows. I followed the postings of Jmackro and Jhjacobs. I hooked up a 12 gauge wire (30 amp fused - orange wire in the pic) to the battery: I had bought dual relay sockets and relays off eBay, removed the open...

e9coupe.com

That is certainly thorough. Thank you.

 

[Stevehose]

That is certainly thorough. Thank you.

I have since fused that circuit as well

 

[jmackro]

I dread taking apart that front console again...

Well, if you add relays, you won't have to take apart that front console again. But I wouldn't guarantee that the total amount of work won't be greater.