1972 280sel power window nightmare!

[MillerLite]

Hi guys, really need help on this one.


Just started putting together my interior on a long restoration.

Power window motors were taken out and lubed two regulator changed.

All terminals cleaned and lubed

Now to the issue.

My front driver and rear passenger windows work perfect, BUT my front passenger and rear drivers windows do not.

Checked power on the NOT working switches and they do have power and ground but instead of reversing polarity they change polarity all together to the motor either sending both positive or both negative, that goes to both doors that are not functional.

The relays were checked, fuses checked

No wiring was ever cut or looks to be cramped anywhere, probed both motors w reverse polarity they work perfect bypassing the system.

I am pretty savvy at wiring but this is kicking my butt.

Any help welcome.

Thank you in advance

[BWhitmore]

Are the front left and rear left window on the same switch? Based on what you have already checked, my guess would be the switch.

[MillerLite]

Originally Posted by BWhitmore

Are the front left and rear left window on the same switch? Based on what you have already checked, my guess would be the switch.

Yes BWhitmore, the switches are connected correctly. I even tried new switches and no avail.

The only iffy part is the order of the wires on the driver rear window switch. It fell apart and I put it back based on the passenger side.

Wish someone would have a pic of the rear window switch with the color codes and plug numbers just to make sure that i have them right.

[BWhitmore]

I would think switching the wires around in the switch will do no harm with the exception of blowing fuses. Given that you do not have a wiring diagram that would be my next step.

[ejboyd5]

I know you tried replacement switches but I still believe that is where the trouble lies. Remove the switches from the passenger front and driver rear and attempt to stimulate window movement using only jumper wires or direct contact made by touching switch leads together.

[tyl604]

What do you use to lube an electrical terminal? I just always sanded them off.

[BWhitmore]

Normally cleaning the terminal does the job, but for extra conductivity and to prevent corrosion use Di-electric grease. Should be available at Radio Shack or Amazon.

[ejboyd5]

Originally Posted by BWhitmore

Normally cleaning the terminal does the job, but for extra conductivity and to prevent corrosion use Di-electric grease. Should be available at Radio Shack or Amazon.

Dielectric grease does a fine job on retarding corrosion, but it is non-conductive, i.e., electrically insulating, by design. There are certain pastes/gels used to increase conductivity at junctions, but the need for them in automotive applications is quite rare.

[BWhitmore]

Good point. I do remember using di-electric grease in a General Motors HEI ignition systems on the spark plug end of the wires and I thought it was for better conductivity but now that I think about it the reason for it's use was to prevent corrosion and to ease the removal of the wire boot.

[hotbasco]

Check and re-check the fuse box. The windows are fused in a cross pattern. in other words the passenger front and driver rear are on same fuse and vice versa. I carry a small box of fuses in my car for just these instances. Corrosion on the fuse can prevent operation. Good luck. Cool car!

[Tony H]

Are both + and - switched or just the +?

[Mike D]

Both. It's a simple DC motor. If you have the door cards off use a 12-18V battery pack (Cordless drill, etc.) and a couple of jumper wires to check the motor operation.

[Tony H]

Yea I guess the switch would need to reverse the polarity to run the motor both ways