heated screens

Post by **Jefftav** » Thu Mar 12, 2009 7:13 pm

Has anyone made a wiring diagram to connect up the heated screens in a Morris. I have fitted front & rear heated screens and have 2x 20/30amp relays to wire in. Can't remember the size of cable I bought but I bought it from an auto electrical shop he confirmed that it could carry the required current to each screen and I have bought two switches meant for heated rear screens.

I think I have worked out that I will fit another (Morris) fuse box connected to the ignition side (so it only works with the ignition switch on). Then connect the relay so it closes with the ignition switch on, then run a cable from the relay to the switch inside the car and from the other side of the switch to the screen. The other wire from the screen will be connected to earth.

This will mean the screen can only be switched on if the ignition is on and the relay activated, does this sound right though? As I think it sounds too straight forward.

Any advice is welcome. Thanks in advance. Jeff

Post by **PSL184** » Thu Mar 12, 2009 7:29 pm

Jeff, I may just be confirming what you have written but in a different way, but this is how I would do it....
One side of screen to earth. Other side of screen to switched side of relay. Relay to earth. Relay to fuse box output. New fuse box powered from ign. solenoid. Screen switch to earth and the other terminal to the other switch position on relay.
I'd draw a diagram nut I'm not sure how I would upload it....?

Post by **alex_holden** » Thu Mar 12, 2009 8:33 pm

I'm not sure it would be a good idea to put that much extra current through the standard ignition wiring and switch. I would connect the new fusebox to the battery side of the solenoid using a new thick wire, and power the relay coils from the ignition switched live via the two switches. That way the relays can only be energised when the ignition is switched on, but the high current to power the heated screens bypasses the standard wiring.

Post by **PSL184** » Thu Mar 12, 2009 8:39 pm

The only power you would be pulling is enough to throw the relay... The relay will take the load....

Post by **alex_holden** » Thu Mar 12, 2009 8:48 pm

PSL184 wrote:The only power you would be pulling is enough to throw the relay... The relay will take the load....

I don't think I understand your circuit description at all then, because it sounded like you were suggesting the new fuse box would be powered by the ignition circuit.

Post by **PSL184** » Thu Mar 12, 2009 8:52 pm

alex_holden wrote:
PSL184 wrote:The only power you would be pulling is enough to throw the relay... The relay will take the load....
I don't think I understand your circuit description at all then, because it sounded like you were suggesting the new fuse box would be powered by the ignition circuit.

Correct - It does... That's because I missed the word "solenoid" out.
Now corrected, thanks

Post by **PAULJ** » Thu Mar 12, 2009 9:32 pm

The power for the screen should not go through the switch, that is why a relay is fitted. send me your email address and ill send you a wireing diagram as i see it. I cant upload it for some reason