3rd brake light not working. CHMSL

[jad1014]

Hello,

My CHMSL are not working. My rear brake tail lights work and hazards work. I unplugged the two connectors going into the stop light switch and the smaller light blue one has no power in the connector. I assume it should have power? Where should I look next? I am afraid i am beyond my threshold with solving electrical issues.

Thanks
Jason

[Matt B]

Brake lights are all in one connector. The other one is to disable the cruise control.

Energy is provided via the center wire whereas the two outer ones route the current to the brake light "clusters" - 4 lower and central high.

Remove the switch (just pull it out towards the inside of the car) and measure the resistances between center and both outer contacts.

If there is an issue open it by carefully prying out the 6 small latches and thoroughly clean the contact points.

Good luck! 161631616416165

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[Corvette95]

I MAY be wrong, but going from memory, both switches will cause an in/op third brake light. I vote either bad switch or just as likely, all those expensive little bulbs in the lamp are out.

[Young1]

Go to Napa and get a new switch. Been there done that. I even took the 30 year old apart and cleaned it. It still did not work. Put in a new one and good for another 30 years!

[DRM500RUBYZR-1]

post 3 and 4 are correct.
It is almost a 50-50 chance that it is one or the other.
Every time we check the switch first, it's all of the bulbs out.
If we check the bulbs first, it is the switch.
Trim limber techs probe the switch first.
The more "executive cut" techs opt to probe the bulb sockets first.
Working under the D/S hush panel can be a contortionists' practice session.
:cheers:
Marty

[jad1014]

post 3 and 4 are correct.
It is almost a 50-50 chance that it is one or the other.
Every time we check the switch first, it's all of the bulbs out.
If we check the bulbs first, it is the switch.
Trim limber techs probe the switch first.
The more "executive cut" techs opt to probe the bulb sockets first.
Working under the D/S hush panel can be a contortionists' practice session.
:cheers:
Marty

Thanks to all. It is only one switch to replace, correct? I though the second switch with the unused plug was for cruise control.

Should this connector have power:

http://www.zr1.net/forum/picture.php?albumid=504&pictureid=4661

[jad1014]

Hi - i replaced the switch and it didn?t solve the problem. Whats a good way to test for power at the bulb? I put a tester on the sauder back section of the board that holds the four lights, but not sure if that?s a good way. What?s a good source for replacement bulbs?

[HAWAIIZR-1]

Hi - i replaced the switch and it didn?t solve the problem. Whats a good way to test for power at the bulb? I put a tester on the sauder back section of the board that holds the four lights, but not sure if that?s a good way. What?s a good source for replacement bulbs?



Some of us have upgraded to LED strips.

http://www.zr1.net/forum/showthread.php?t=30223


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[Matt B]

Whats a good way to test for power at the bulb?

Maybe to open the brake light and measure at the sockets. If you have to replace bulbs you need to open it anyway.
You may also try to measure resistance between the plug and ground. If the circuit is closed (I.e. At least one bulb is okay, circuit board is okay and there is a proper ground) there should be any reading. If there is no reading circuit is broken somewhere. From here I'd open the brake light and check everything inside.

As for the bulbs due to the lack of availability of that US standard on my continent I replaced mine with 8 watts G4 standard socket halogen bulbs. They are a bit larger but squeeze in nicely. These are also available as LED.
16174

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[jad1014]

I don?t think I have power to the CHMSL bulbs. The SLS switch has been replaced and I found some 891 bulbs and replaced two with no luck. I think that?s about as much as my skill set will offer for this problem. I didn?t bother with the 20A fuse since my hazards work. Any other thoughts? Thanks again.
Jason.

[Matt B]

Did you check for proper ground? I don't remember how ground was routed to the sockets but if your lower brake lights work and the switch is new it's likely that current is available at the sockets. So maybe an issue with grounding?
I'd check for both, ground and current at the sockets first and then follow the path that doesn't work.

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[jad1014]

I haven?t checked a ground. I did get the FSM recently and will check it for the ground location- thanks

Here is what the wires look like going into the SLS. The light blue wire is for CHMSL if I understand correctly? White goes to the turn/hazard switch assembly if I understand the FSM. What is the orange - a ground? What?s the small blue plug? There is some tape on the three wires going into one of the SLS connectors. I?ll have to take it off and see what I see.

http://www.zr1.net/forum/picture.php?albumid=504&pictureid=4663

http://www.zr1.net/forum/picture.php?albumid=504&pictureid=4664

[Z51JEFF]

It's the switch,I've replaced it 3 times in 15 years. One down side to doing the Euro taillight conversion,when the switch goes out you have no brake lights at all.

[jad1014]

It's the switch,I've replaced it 3 times in 15 years. One down side to doing the Euro taillight conversion,when the switch goes out you have no brake lights at all.
I replaced the switch. I was fully expecting a done deal after replacing the switch based on all the good threads I found in search.

[Matt B]

Orange is current. That's where your energy comes from. Should attach to the center lug of the three.

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[jad1014]

Orange is current. That's where your energy comes from. Should attach to the center lug of the three.

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Thank you.

[Corvette95]

I MAY be wrong, but going from memory, both switches will cause an in/op third brake light. I vote either bad switch or just as likely, all those expensive little bulbs in the lamp are out.
Please spend the $10's a buy the second brake light switch, one controls bumper lights the other controls the high mount. BOTH need to be working.

[jad1014]

Please spend the $10's a buy the second brake light switch, one controls bumper lights the other controls the high mount. BOTH need to be working.

My understanding is there is one brake light switch, two connectors. One connector for the bumper lights, one for CHMSL.

http://www.zr1.net/forum/picture.php?albumid=504&pictureid=4663

The orange white and blue go into the SLS. The second blue connector with the grey and a black/white wire also goes into the SLS. No?

[Matt B]

Only the triple connector is involved in brake light action. As already stated: the center one feeds energy, two outer ones route it to the brake lights when the switch is engaged.
The other connector to my knowledge disengages the cruise control but I'm not 100% sure.
You may try to bridge the connector with a bridge lead center-left and center-right which should engage your lights. If not there is a broken circuit. Also you can measure resistance between the connector and the bulb socket to check for a broken circuit. Refer to the FSM to find out which wire is yours.
Again: easiest point to start from is to measure at the third brake light sockets. You either lack positive or ground. Find out what's missing and follow the path down to either the body or switch.


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[Z51JEFF]

Anybody working on this keep in mind you cannot unplug the switch and just leave it and get back to it latter. Once the switch is unplugged the lights will stay on,ask me how I know.

[jad1014]

Only the triple connector is involved in brake light action. As already stated: the center one feeds energy, two outer ones route it to the brake lights when the switch is engaged.
The other connector to my knowledge disengages the cruise control but I'm not 100% sure.
You may try to bridge the connector with a bridge lead center-left and center-right which should engage your lights. If not there is a broken circuit. Also you can measure resistance between the connector and the bulb socket to check for a broken circuit. Refer to the FSM to find out which wire is yours.
Again: easiest point to start from is to measure at the third brake light sockets. You either lack positive or ground. Find out what's missing and follow the path down to either the body or switch.


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Using a test light -The orange center wire is always energized. The blue wire is energized when the brake is pressed. The white is not energized when the brake is pressed.

I checked at the CHSML lights by probing the wires going into the bar that holds the four bulbs. No energy when the brake was depressed. Thanks again for your insight.

http://www.zr1.net/forum/picture.php?albumid=504&pictureid=4668

[Matt B]

If one wire is not energized, i.e. the respective (outer) connector of the switch remains cold with the pedal depressed, the switch is faulty. Refer to my picture in post #2. You said you replaced the switch, no? Did you install a brand new or used one?

[jad1014]

If one wire is not energized, i.e. the respective (outer) connector of the switch remains cold with the pedal depressed, the switch is faulty. Refer to my picture in post #2. You said you replaced the switch, no? Did you install a brand new or used one?

New switch from NAPA.

[Matt B]

Where exactly did you hook up you test light for ground and positive? And was the connector attached to the switch or not during test?

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[jad1014]

Where exactly did you hook up you test light for ground and positive? And was the connector attached to the switch or not during test?

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The positive was probing the connector itself while plugged into the switch. The ground was on bare metal that was beneath the trim panel that was removed to access the wiring. The car is going to a mechanic tomorrow. My fundamentals are weak in this area as one can tell.