Stop light switch wiring

[Martin Evans]

Hey everyone! I'm in the process of rebuilding the inside of of my '89 Silverado because several years ago, some a*****e thought it would be fun (I guess) to light the inside of my truck on fire. Since I had to redo the whole interior, I figured I may as well do some upgrading. One of the upgrades was adding the 3rd brake light/cargo light. I tapped into the dome light, grounded the stop light with the dome light attachment screw and ran the + to the brake switch and the assembly itself works as it should. Here's my problem(s) - first, instead of having an orange and a white wire going to the stop switch like all the wiring diagrams show, I have a gray and a green wire. My second problem is I don't know which wire is supposed to be the +12v and which wire goes to the taillights since I'm not getting any power or ground to either one. I'm also not getting power to my headlights although I have power at the headlight switch. I also verified that the headlight dimmer switch is working and the fuse is ok. I'm guessing it's a broken wire after the fuse that feeds both the headlights and stoplights (I think they are on the same fuse, aren't they?), but I'm still troubleshooting. Anybody else have gray/green wires instead of orange/white wires going to the stop light switch? And if you do, can you tell me which one is supposed to be +12v?
Thanks!

 

[GoToGuy]

You have a pre " high mount stop light". You need to reference a 95 wire diagram , section 8A-110-2 and 8A-110-4. These are the wire diagrams showing the circuit. They're in the factory service manual.
Are using the OE service manuals for your year? They're a fee download in the forum. Don't guess with electrical. For your upgrade you should download both 95 service manuals book 1 and book 2. It will tell you everything you need.
Grey and green are tail light colors.
Are you using factory wire diagrams, the Chilton and others are too generic.
Good luck.

 

[GoToGuy]

Neither does, orange, number 140 supplies power to switch for brake light activation.

 

[Martin Evans]

Neither does, orange, number 140 supplies power to switch for brake light activation.

Thanks for your replies. I don't have an orange or white wire going to my stop light switch unless the switch operated by my brake pedal isn't the stop light switch. Just the gray and green ones going to that. I'm keeping the truck at a friend's house so I can't take a picture tonight, but the next time that I go over there, probably tomorrow, I'll take a picture.

 

[GoToGuy]

The GM factory service manuals are here in the forum, a free download. You wanna do your own work there your new best friend.

 

[Martin Evans]

I'm pretty new here. How do I find them? Thanks in advance.

 

[GoToGuy]

Thread '88-98 Service Manuals' https://www.gmt400.com/threads/88-98-service-manuals.43575/

 

[Martin Evans]

Thread '88-98 Service Manuals' https://www.gmt400.com/threads/88-98-service-manuals.43575/

Thanks for all your help! I looked up a brake switch and found out that there are two switches there and the one I found wasn't the one I was looking for. Thanks again!

 

[GoToGuy]

Good luck!