Switch
Thread Starter
Racer
Joined: Mar 2015
Posts: 306
Likes: 20
From: Greenville SC
Switch
Getting ready to replace the combination(proportioning) valve on my 79 L48. been having issues with brakes for a while now. The valve is the only part that has not been replaced on my brake system. I checked the wire running to the valve that illuminates the brake light on the dash. There is no power going to it. I pulled the emergency brake light switch located at the brake handle and the is no power going to it either. I checked after I removed the switch. Does the switch have to be grounded to receive power????? I had the ignition switch on when I checked for power to the emerg. brake switch.
Thanks
Thanks
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
Yep. And there are MANY electrical items in a C3 which have 'switch-activated' grounding circuits. Electric power can be applied by completing the circuit anywhere in that circuit's path: 12vdc power line; the electrical device; or the grounding path.
You can check that circuit out using the ohmmeter function of you multimeter.
You can check that circuit out using the ohmmeter function of you multimeter.
Last edited by 7T1vette; Dec 20, 2020 at 09:46 AM.
Le Mans Master
Joined: Dec 2007
Posts: 6,422
Likes: 591
From: McHenry Illinois
You can test the circuit by turning on the key and then ground the wire at the park brake switch or the brake failure switch (proportioning valve). I the light doesn't come on, you may have a bad bulb or fuse.
Race Director
Joined: Mar 2017
Posts: 11,949
Likes: 4,507
From: Virginia
There are three ways to illuminate the "Brake" light on your dash.EDIT: With the key in the ON position, prior to start, the ignition switch grounds the light (so it should illuminate briefly before you start the car).
With the parking brake handle pulled up slightly, the plunger switch will release, close the contact to ground, and illuminate the light.
And the switch in the combination valve also acts as a ground if the plunger is offset to one side or the other.
I none of these work, especially the first one, I'd check the bulb, and perhaps the flexible circuit board at the back of your dash cluster. This was specifically an inspection item that I had to address in my 79 L48.
Last edited by Bikespace; Dec 21, 2020 at 02:45 AM.
Team Owner
Joined: Jan 2006
Posts: 37,637
Likes: 3,118
From: Crossville TN
All correct above...except that the light comes on with ignition switch only turned to the ON position (prior to START position). This feature is on ALL vehicles so that the gauge panel bulbs can be tested. If a gauge 'icon' does not illuminate when key is in the ON positon [engine OFF], the bulb is bad.
P.S. For more modern vehicles with push-button [keyless] start feature, the dash bulb test is performed by depressing the start button without your foot on the brake pedal.
P.S. For more modern vehicles with push-button [keyless] start feature, the dash bulb test is performed by depressing the start button without your foot on the brake pedal.
Last edited by 7T1vette; Dec 21, 2020 at 12:19 AM.
