How many brake light switches?

[GTOger]

Quick survey. How many brake light switches does (should) a 1990 ZR-1 have?

1) one
2) two
3) other

I'm asking because my brake lights quit. So I ordered a brake light switch, removed the hush panel, became a contortionist and then found there are two under there.

One's white, the other black. The white one has the electrical and vacuum connections, but there is nothing plugged into the electric. Only the vacuum line is connected. The black one has a connector with blue & gray wires.

Huh? Did someone "customize" it? Or is that what I'm supposed to see?

[Paul Workman]

Originally Posted by GTOger

Quick survey. How many brake light switches does (should) a 1990 ZR-1 have?

1) one
2) two
3) other

I'm asking because my brake lights quit. So I ordered a brake light switch, removed the hush panel, became a contortionist and then found there are two under there.

One's white, the other black. The white one has the electrical and vacuum connections, but there is nothing plugged into the electric. Only the vacuum line is connected. The black one has a connector with blue & gray wires.

Huh? Did someone "customize" it? Or is that what I'm supposed to see?

TWO switches: (Ref Electrical section; pp 8A-110-0 & 8A-110-1 )

Battery power passes through the STOP/HAZARD (20A) fuse to a green wire that connects to the brake pedal switch (also to a capacitor wired in parallel to the switch, but forget that for now).

Two wires leave the pedal switch:

the lite green powers the 3rd (high) brake light, AND too a branch goes to the ANTILOCK circuit.

the white wire connects to the HAZARD/BRAKE switch and normally routes power from the brake pedal switch to the brake lights (unless the HAZARD mode is selected)

From there, power is routed from the HAZARD/BRAKE switch via dark green wires to the stop/hazard/turn bulbs. From the bulbs, a black wire is connects to the the ground lug G401 (ref 8A-14-11): be sure that ground connection is good (or nothing works!).

So... Trace the path (in the FSM) and repair whatever component is NOT functioning (much preferred to "changing parts until the problem goes away").

[conesare2seconds]

The one with only vacuum connected is likely for the cruise control.

[GTOger]

Thanks! I'll have to check it again when I get home. The black switch will certainly have to be replaced because the plunger isn't popping out at all. Which would be a good reason for the brake lights not to come on.


I'll also be on the lookout for a FSM.

[Mystic ZR-1]

Do both while you're at it.
Avoid the aggravation on of going in there again.
They're cheap.
The switch for the 3rd brakelite is
a common Problem.

[GTOger]

Got it. Yup, I'll replace both of 'em. Why the heck not. Though from the looks of things, this car was not engineered for those parts to be serviced! Well, unless your mechanic happens to be the size of a smurf but with really long, bendy arms and fingers.

[Mystic ZR-1]

Take 10 minutes and remove the driver's seat.
4 bolts and a couple electrical connectors
Makes it a lot easier to work under the dash,
you won't have to contort
your body as much

[Paul Workman]

Originally Posted by GTOger

Got it. Yup, I'll replace both of 'em. Why the heck not. Though from the looks of things, this car was not engineered for those parts to be serviced! Well, unless your mechanic happens to be the size of a smurf but with really long, bendy arms and fingers.

I think that is (partly) why Marc Haibeck is so successful. He is the only guy I know that can work under a ZR-1 w/o putting it on jacks!