> I am trying to figure out the electrical system on a 1997 GMC Sonoma
> > pick-up truck. The problem I'm having is trying to understand the
> > schematic diagrams. I have a set with bit more detail from Haynes.
> > The diagrams depict the SUV which is similar. The area of interest is
> > the Hazard/Turn/Stop functionality. The rear has one bulb per side
> > with a filament for tail illumination and another filament for Stop/
> > Turn. The front has one bulb per side with a filament for parking
> > illumination and another filament for turning. Also, there is one
> > sidemarker per side in front which integrates both parking and turning
> > functions. I understand how the brake lights work with and without
> > the turn signals on. I have also read about the strange way the turn
> > signals work with the parking lights. Although, I think the schematic
> > is incorrect. The real problem I can't figure out is when the hazard
> > lights are on and I apply the brakes, all the lights that are flashing
> > remain on (front, rear, and dash). This allows someone to know your
> > braking when the hazard lights are on. But what makes it happen? I
> > can't figure it out from the schematic. Is it me or the diagram? Can
> > anybody figure it out? You can find my wiring diagrams at
> >
formatting link
Thanks!
---------------------------------------------------------------------------------------------------------------- > In your diagram, the Stoplamp switch passes 'always Hot' power around
the hazard flasher.
>
> If you were to disconnect the white wire, it would not stay on despite the
> brakes being applied.
>
> Find connector pin 17, the white wire and remove it. Apply 12 volts to
> the socket at the point and the lights will come on just as if you were
> braking.
---------------------------------------------------------------------------------------------------------------- July 18, My response
I believe you misunderstood my question. I know that the stoplamps are fed always hot power through the Stoplamp Switch. However, when the switch is activated, that power is routed through the Turn/Hazard Switch Assembly, which determines which stoplamps can illuminate. The CHMSL is the exception, which can illuminate independent of the Turn/ Hazard Switch. The diagram shows though that when the hazard switch is on, the stoplamp circuit is broken. But when I apply the brakes with the hazard lights on, the dash turn indicators cease to blink. Instead, they illuminate continuously until I release the brakes and they begin blinking once again. Thus, at the rear it would appear your stoplamps were on and at the front brighter parking lamps. Do you agree the diagram is incorrect? If so, how should the diagram appear to make me understand why "all" the hazard lamps freeze "on" with the brakes applied (i.e. what was Haynes' error?)? Also, wouldn't you agree that there are several more errors to the Turn/ Hazard Switch Assembly? Look at the turn signal power input to the assembly. It doesn't get routed to all the right places.