Interior light on 720

[Kennyt]

Sometimes she works when door opens. Sometimes she dont. Only works when cold outside. Anyone have a wiring diagram?

[Rhino13]

I thought mine was messed up when I first got it but you may just have to pinch the switch and move it forward or back. Middle is off, forward is always on, back is on when door is open.

[datsunaholic]

Year matters- some 720s (like my '83) has a fade-out timer when you close the door.  But in your case I'd suspect that the door switch is the culprit, they tend to get stuck pushed in (which leaves the light off).

[Kennyt]

Thanks. I will check the switch today tonsee if stuck or has any issues

[datzenmike]

They rust. Work the push button by hand 30-40 times to clean the contacts.

[MaxChlan]

If that doesn't end up working for you, I have a FSM with the wiring diagram for the 1984 model year that I could send pictures of. 

[DanielC]

A typical door light switch works by supplying a ground to a light that always has power supplied to it.   40 or so years of wear, dirt, rust and corrosion can make the ground go away.   Try removing it, and cleaning the contacts, and the connection between the switch body, and cab sheet metal.  check also the contact between the wire going to the switch and the moveable part of the switch.

[Kennyt]

I know it has been a while but still no luck. However when it is cold outside the light will work. Any ideas?

[datzenmike]

The door switches are rusty. Push them in and out many times to clean them.

 

They rust. Work the push button by hand 30-40 times to clean the contacts.

[mx71]

My guess is one of the door switches is failing or you have a bad ground. Clean the holes that the switches screw in to. Could also be a failing door timer switch under the passenger seat. I ended up just bypassing my door timer altogether.

[Kennyt]

Thanks. Do u have a pic of the timer?

[datzenmike]

 

This is the fuel pump relay/timer which is very similar to the wiper delay timer which is also very similar to the interior light timer. Just different timer settings.It's under the passenger seat. It will have....

 

Black............. ground

Black/Red..... Driver's side door, grounds to turn light on, sets timer when door closed.

Red/Black..... passenger side door, grounds to turn light on, sets timer when door closed.

Red/Blue ..... power at all times from the #13 fuse 3 from the right side.

BrownRed ... grounds the interior lamp to turn it on. King Cab does have a 3 way switch on the dome light to turn room lamp off.