Underdash and door light inop!

guevara42 · Sep 13, 2008

I just noticed that my underdash and door courtesy lights are not working. All I've done to the car since I noticed them not working is put in an electric fan and a new alternator. Any Ideas? TIA.

TOM B · Sep 13, 2008

guevara42 · Sep 13, 2008

TOM B said:
fuse

Posted via Mobile DeviceI forgot to ention that all tje fuses are good.

other_shoe · Sep 14, 2008

From your, post I'm guessing they are not coming on in any configuration (not with either door and not with the headlight switch). If not, be sure to do so and rule out the door switches. Also, make sure you are getting a good ground and check the underdash light bulbs (I know it's unlikely they'd fail together, but it will take one minute). After that, it's a problem with the headlight switch (and/or the connector), wiring, or getting power from the fuse box.

After checking the easy stuff, I'd start at the fuse box and go up the circuit with a multimeter checking for both voltage and continuity. Turned out to be rust on the fuse box terminals for me -- a bit less likely for you, but I'd still check while hunched under the dash.

guevara42 · Sep 14, 2008

other_shoe said:
From your, post I'm guessing they are not coming on in any configuration (not with either door and not with the headlight switch). If not, be sure to do so and rule out the door switches. Also, make sure you are getting a good ground and check the underdash light bulbs (I know it's unlikely they'd fail together, but it will take one minute). After that, it's a problem with the headlight switch (and/or the connector), wiring, or getting power from the fuse box.

After checking the easy stuff, I'd start at the fuse box and go up the circuit with a multimeter checking for both voltage and continuity. Turned out to be rust on the fuse box terminals for me -- a bit less likely for you, but I'd still check while hunched under the dash.

I checked all the fuses, good. light bulbs, good. I must have a short somewhere bcuz I remember opening the door yesterday and they were on and drove the car. When I got back, is when I noticed they were out. All my other light work. The instrument bezel, headlights, hi-beams. I will try to isolate starting at the fuse box.

BarnStang · Sep 14, 2008

Start at the door switches. Make sure they have a good connection. THey can come loose, fall off. Need to know what year the car is-will pull up the applicable diagram...

guevara42 · Sep 14, 2008

BarnStang said:
Start at the door switches. Make sure they have a good connection. THey can come loose, fall off. Need to know what year the car is-will pull up the applicable diagram...

It's a 66 coupe, 289. I appreciate your help.

mustangman1974 · Sep 14, 2008

door switches or your ground strap from the engine might be loose

BarnStang · Sep 15, 2008

Popwer is fed from the headlight switch. Each bulb is individually grounded. So if you lost ALL the courtasy lights, it's almost has to be somewhere between the headlight switch and the door buttons.

Notice that the door button is connected to wire 53 black/blu strips and wire 54 green/yell strip. And that both go back to the headlight switch. The green/ye; strip should have power all the time-example-glove box light. The black/blu strip should be controled by the door buttons. When you click the detent on the headlight dimmer, it sends power to the black/blu strip wire to turn on the courtasy lights with the doors closed. The console feeds are right up under the center of the dash at the firewall, above the fusebox. Also, check the headlight plug and make sure it has not come partially off the headlight switch. Also, watch that none of the terminal connectors have pushed back out of the headlight plug. Sometimes tha catches fail and can let one or two wires push out of the connector plug when you push it onto the headlight switch.

guevara42 · Sep 15, 2008

Thanks guys. And thank you BarnStang for the schematic and info. I will keep you posted to see what I came up with once I look deep into it. :SNSign:

Underdash and door light inop!

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