How do you wire a switched hatch lamp?

[Jose A.]

my '97 Aerostar XLT came with a tiny unswitched lamp which always comes on when you open the rear hatch. Sometimes I do not want the light on. I removed it and it has two wires, assumedly Hot and Ground.

I got a larger lamp from a '96 which has a three position switch: ON-OFF-DOOR. but this one has three wires.

I don't know if the third wire is in the van's harness but disabled, or if there is no third wire in the van's harness.

How can I make this work if only two wires are available?

Thanks.

 

[BrooklynBay]

There should be a constant power wire (+) in the harness, and a power wire (+) which is only switched on when the door is open. The body of the vehicle is your ground connection.

 

[Jose A.]

ok, but the replacement lamp assembly is all plastic, housing and lens, no metal to speak of in order to ground it to the body, no metal tabs to ground to the body either.

in the wiring of the replacement lamp, there are three wires: one Green wire connects to the DOOR switch position, one Black with Blue stripe wire connects to the ON switch position, and one Black wire connects to one of the Bulb terminals;

then from the bulb, another Black wire connects to the OFF switch position.

If both existing wires in the van's harness are Hot (+), how do I ground the new lamp?

 

[BrooklynBay]

When I mentioned the ground connection, I was referring to the body of the van. Anywhere you mount a screw to the body will be a ground connection. The solid black wire is generally the gound connection. You could confirm this with a continuity tester or a test light. One of those power wires is a constant (+) while the other one is only (+) when the door is open. Here's a schematic from my Ford software:

 

[Jose A.]

thank you for the schematic, I will study it in detail and somehow figure this out. As always, I'll blow a few fuses before getting it right.

where can I get a Shop Manual that is NOT a Chilton/Haynes? I would like a Ford Shop Manual for Aerostar if it exists.

 

[BrooklynBay]

Check EBay.