electric windows breaker int, how to install ?

[deQuincey]

hi

my car is dated 1971, I have electric motors only in the rear windows

I have been told that in later cars a breaker circuit system was implemented, part number 3, ( my car has not got one of those )

I can order that part from bmw now or even get a second hand one, but my question is if you know how it has to be installed ?

do i have to connect it to the positive cable ? do i have to let the positive lead through it before the electric motor terminal ?

is it enough one breaker for the two rear windows ?

 

[HB Chris]

They were introduced mid 73 when the motors and regulators were changed. It doesn't add anything that a fuse won't provide, no more current, etc.

 

[61porsche]

The wiring diagram

is in the repair manual for the detail on the windows. If your rear only euros are fused left and right, then yes two circuit breakers if that's what you want to do.

Yes power from the fuse box to the breaker first.

There's no reason to do this, but if you insist- buy a new type with a thermal reset that you never have to touch as on more modern cars. ( Works, cools down, and works again)

If you're loosing voltage at the motor, you need to fix that first, clean the switches, etc. The alternative is a hot start relay- the switch just triggers the relay like the headlight upgrade discussed. There should be an article/ discussion regarding adding relays on the window motors here by searching-something about a contest for fastest and slowest windows in the west!


Check your wiring for which fuse serves the carb idle solenoids and it's not the windows otherwise you can get into a no run situation if the fuse blows. I just don't recall which fuse off the top of my head.

 

[deQuincey]

is in the repair manual for the detail on the windows. If your rear only euros are fused left and right, then yes two circuit breakers if that's what you want to do.

Yes power from the fuse box to the breaker first.

If you're loosing voltage at the motor, you need to fix that first, clean the switches, etc. The alternative is a hot start relay- the switch just triggers the relay like the headlight upgrade discussed. There should be an article/ discussion regarding adding relays on the window motors here by searching-something about a contest for fastest and slowest windows in the west!
.

thanks jerry, yes i got the nice information from stevehose about how to incorporate relays, and I have all the necessary parts to do so

but i was considering additionally to install the breaker to avoid damages to the motors if any problem occurs

so, if i upgrade it with relays that means that:
1- i will introduce a fresh new positive lead from the battery, using an aerial fuse for it,
2- i will place the breaker in the path of this positive cable, but near the dash to be able to operate it (i prefer the old fashioned to-be-pushed version, thanks for the tip on the thermal one anyway)
3- then i will do all the relays according to stevehoses tutorial

what do you think ?

do you think this is sound ?

 

[61porsche]

Yes

sounds good.

 

[HB Chris]

The wiring diagram with the circuit breakers is included on 61-0/48 in the Blue Book, `73 and on but this diagram is reallly `74 specific as it has a low beam relay. A lot of mix and match to figure nthings out. The 72 diagram in the e9 Registry area has no window motors or switches.

 

[deQuincey]

thanks
sorry for delay in answering
regards

 

[deQuincey]

sounds good.

completing this here it comes graphically:

this is the schematic drawing of the power motor windows electric upgrade inlcuding relays:

and this is my idea to introduce a breaker in the 12v positive cable:

do you think it is correct ??

 

[61porsche]

The switch

wiring- as long as the switch is just signaling the relay. That way you're eliminating the switch as a point of resistance.

Your motors- are they original as in the silver "tuna" can type like in the manual or the e28 type? The reason is how the switch and motors operate. The original way was three wire with 2 dedicated power wires. The E28 motors require two wires with only one power wire and a ground. That type motor requires the switch to act to reverse the single wire for both up and down.

Ditto on Jay's points. Try not to induce resistance.

Clean the switches with contact cleaner.