Re: 1948 brake light switch

Posted by Wesley Boyer On 2012/12/1 13:28:50

Maybe I can get you pointed in the right direction.
First I'm assuming that it's wired according to the the factory schematic. So download a copy of the schematic and I will try to walk you though, you also need a volt meter.https://www.packardinfo.com/xoops/html/downloads/wirediagrams/48-9%20%2022nd%20Series.pdf
Next since you said you have power at the brake switch your Courtesy and Glove Box lights should be working also, and it would help to have a second person to press the brakes for you.
Now go to the bottom of the first page and find the STOP LIGHT SWITCH, two wires connected to switch 13-R (Red wire should be power) and 14-G (Green). Follow wire 14-G at the bottom of the next page from left to right. 14-G goes to a connector, up under the dash, which is what HH56 was talking about earlier. Just make sure the wires are all connected, this should be 14A-G going overhead to the trunk.
In the trunk you should find the green wire (14A-G) with two more wires connected to it(14B-G & 14C-G). You can see this on the third page of the wire schematic. At this point it would be good to run a wire from the + post of the battery and check the for voltage on the green wire at that connector. When the brake is pressed you should read voltage (Over six volts, depending on how much your battery is charged.) If you read voltage there, than touch the wire from the battery to the light housing and the brakelight should come ON (while pressing on the brake). (This is what OD was talking about when he said find a good ground.) If the brakelight comes on than it is a ground problem and you will need to find a way to run a wire from the brakelight housing to the frame of the car.
If no voltage than you will need to get under the dash and check the wiring and see if you get any voltage readings while pressing the pedal.
I hope this helps.
Wes