Brake light help

[rputney01]

I've got a '79 GS1000S that I cleaned up over the winter. I've been stumped for 2 weeks with a brake light issue I can't figure out. I'm a true noob and this is probably pretty simple, but I can't get it.

I turn on the ignition and get a tail light, a license plate light and a headlight, but the neutral light in the instrument cluster doesn't light. The horns, which are on the same circuit, don't work. The brake light doesn't come on with either the front or back lever/switch. The bulbs are new. I have power into the fuse box, the fuse is fine and 10.9 volts coming out of the fuse box into the first connector going out to the circuit. I've cleaned and greased all the connectors into the tail/brake light, in the wiring harness and in the headlight bucket. There is no power in the circuit in the headlight bucket in the wires to the switch when I pull the handle for the front brake.

As a last gasp before giving up last night, I tried to jump directly from the battery to the brakelight in the connector at the back. Nothing. I then jumped from the battery to a post on the horn. From the wiring diagram, I think it must have been the negative post. It was the one toward the front of the bike and the easiest to reach. The horn didn't work, but the neutral light in the instruments and the brake light came on.

Now I know that I should be able to take that knowledge and do something with it, but despite an hour of looking at the wiring diagram, I'm still stumped. As I look at the circuit near the instrument panel, there is something in a box labelled REG. I assume that this means regulator, but I can't find anything physically on the bike near that location that rings a bell. An excerpt of the wiring diagram is attached.

Your help would be greatly appreciated.

Thanks.

[J_C]

I wouldn't jump unfused power from the battery to any components.

What you need to do is follow the wiring through. Without being able to see the entire diagram it's hard to tell. But it sounds like a connector is loose or disconnected.


Also regarding the reg... hard to tell what that is without seeing what that wire runs to. Someone with your year bike my know right off hand.

[SqDancerLynn1]

First thing to do if figure out why you only have 10.9 volts on the fuse block. Unless your battery is bad ?

[jadesystem]

Most likely it is the black and white grounding wire in the circuit.
Most likely it is not making good grounding to frame ground where
the electrical in your sub-system makes an electrical loop to complete
the circuit.

This black and white ground wire (I'm assuming yours is this color)
goes throughout the instrumentation bulbs, gauges, front and rear
head and tail lights, and everywhere else.

A reference in your schematic, as apposed or similar to my GS1100esd
model, there is a ground wire from the electrical buss (or harness) that
goes to ground. Check this connection and for corrosion. Somehow, it
may be confused and "grounded" to the RR side panel, which is isolated
by rubber grommets.

This is the problem I had, and hope your problem is resolved very quickly.

Good luck to you !!

[rputney01]

First thing to do if figure out why you only have 10.9 volts on the fuse block. Unless your battery is bad ?

Agreed, and on the list of things to do. A month ago, I wouldn't have realized that this was a problem. The more I learn, the less I know. For now, I'd be happy to get it on the street.

[rputney01]

Most likely it is the black and white grounding wire in the circuit.
Most likely it is not making good grounding to frame ground where
the electrical in your sub-system makes an electrical loop to complete
the circuit.

This black and white ground wire (I'm assuming yours is this color)
goes throughout the instrumentation bulbs, gauges, front and rear
head and tail lights, and everywhere else.

A reference in your schematic, as apposed or similar to my GS1100esd
model, there is a ground wire from the electrical buss (or harness) that
goes to ground. Check this connection and for corrosion. Somehow, it
may be confused and "grounded" to the RR side panel, which is isolated
by rubber grommets.

This is the problem I had, and hope your problem is resolved very quickly.

Good luck to you !!

Many thanks. I hope that it is something this simple. At least I have a place to start in the morning.

[jadesystem]

Hi Friend,

Best is to get a Suzuki manual with the electrical schematic. Use an Ohm meter and disconnect the battery or pull the main fuse out. Then follow and trace the wires going to that particular sub-system. In fact, I'm doing
that now on my bike for a Memorial Day weekend with TomMLC here in San Jose, CA.

I also have an electrical problem in the same area, yet have spliced into the wiring harness into the Instrumentation Panel.... just like you will. What I've discovered is the male and female solderless connectors will wear-out and become intermitent with the mating connection. The female
will enlarge so there will be no connection. I've had to jump about 5 wires because of this......and the incompetent Suzuki dealer who cannot order me any solderless connectors/lugs from Japan for this specific wiring harness. I could find who the mfr is, but would have to investigate this and I don't have the time for it. Nor do I want to devote anymore time being a sleuth.

The instrumentation lights are connected by the black and white ground wire and a grey wire which is 12V power to all of the lighting circuit. i.e. turn signals, tail light, instrumentaion bulbs, etc..... I just T/S this to find another wire that is open. So I have to splice again and add wire to it
with a male and female quick-release connecter in case I have to take
the gauges out again.

Good luck to you

:-D\\/