1991 E-Glide Classic brake light problem

[les]

Brake light not working.  I think I have two problems.  First, I determined that the rear brake light pressure sensor (under the bike) does not produce any continuity when I press the rear brake peddle.  When I jumper the two wires that connect to that sensor (ignition on) the rear brake light still does not come on.  (The rear running light does come on and is working properly).  So, setting the sensor aside, I think I have an additional problem because jumpering should have made the brake light come on.

I've attached two pictures.  The picture with the light brown, green, purple, blue, and red wires is under the left side panel and this goes to the back lights.  The other picture is under the seat.  The under the seat red wire appears to connect to the red wire in the other picture through a connection block.  For the under the seat picture (one red and two black) I'm afraid to connect them because the black wires are ground, and connecting a red to a black ground scares me.  I'm not sure if that red wire is a ground, but still I'm thinking...did this red wire accidently become disconnected from one of those two black wires.

For the under the panel picture, can anyone please describe each of the colored wires?  Also, is that under the seat wire a ground wire and should I connect it to one of the black wires?

[Ohio HD]

I'd start here, go to 1991-1992-Wiring-Diagrams-and-Electrical-Troubleshooting-Guide



https://harleytechtalk.com/htt/index.php/topic,16691.0.html

[les]

Thank you again, Ohio.  And still if anyone has any answers/advice, please post.

[les]

So, looking for some advice.  I took the front fairing off and disconnected the front right controls connection block.  I get continuity on/off when I go across the pins for the orange and red wires (third pins down right across from each other) when I squeeze and release the front brake lever.  So, it appears the front brake lever switch is working ok.  I get continuity all along the wiring, so don't believe there are any breaks in the wiring itself.  This leads me to think it's two things that need to be replaced.  (Note: The customer says the rear brake never eliminates the brake light and the front eliminates the light "half the time".) 

The rear brake pressure sensor never produces continuity across the terminals when I push the rear brake lever.  So, I'll have to replace that switch.

When I jumper the wires going to the rear brake pressure switch (ignition on) the brake relay clicks and makes the front suspension dive relay click, but the brake light does not come on.  So, I'm thinking this brake relay probably needs to be replaced.  This "might" be consistent with front sometimes working (relay is flaky) and rear never working (rear pressure switch is dead).

Opinions before I go off and start buying these parts?

[Hossamania]

Have you checked the bulb, tried a new one, looked at the socket, tested for power there?

[les]

Problem diagnosed.  Two things failed at the same time, which made the diagnoses take a while.

I went to AutoZone and got a new brake relay.  That fixed the front brake light problem, and when I [now] jumper the rear brake light switch, the brake lights also work.

So, now I just need to get my hands on a rear brake light switch, R&R it, bleed the brakes, and the bike will be rolling out of my garage.  And, he won't be getting any more tickets for not having a brake light, and it will take about a year for my hands to get clean again from all that oil sludge I had to swim through because of his EVO leaking base gaskets.  lol

Thanks for all the help, I really appreciate it!