Stop Lamp Checker

Striker1423 · May 28, 2021, 09:31:13 AM

So, I ran into this issue when I initially switched the stop lamp to an LED. The lamp checker flashed the stop lamp bulb constantly. So, I removed the bulb and away I went. This might sound counter-intuitive, but since switching to the Vape ignition, I wanted to switch back to a regular bulb and just use the LED as a spare. Simple reason, I wanted the stop lamp indicator to just work.

Obviously I re did the whole harness. Everything is working better than it ever has... But, the stop lamp light is always on. The rest of the dash lights aren't though... So, either the lamp checker relay is staying powered, or, I hooked something up wrong. Anyone have any thoughts?

teazer · May 28, 2021, 10:01:01 AM

Stop lamp checker relay? What is that?

Normally the brake has a switch which has switched 12v on one side and then goes to the brake light bulb and from there to ground. You don't need an idiot light to let you know that the brakes are on, unless you seriously distrust the wiring.

If you wire up a front and rear brake switches, they must both have 12v switched on one side and the output sides should be connected so there's one lead to the rear (brake) light.

Not sure why you would want an idiot light or why there's a relay in the circuit except to feed the ignition. The rest of the circuits should not be on that same relay feed to the ignition. If you want to use a relay on the light circuits I would recommend its own relay. I often do that for headlamps.

The flasher can is a relay and flashers should have an idiot light in the headlamp. Has something be wired incorrectly?

rodneya · May 28, 2021, 10:26:52 AM

Stop lamp checker is meant to be an idiot light to tell you your brake light bulb is blown if its on all the time

teazer · May 28, 2021, 02:39:05 PM

So if the resistance is low with say an LED bulb, it would probably be on all the time? Was that an optional extra or OEM? I don't recall ever seeing one on a bike and not sure I see the need for one. I always check all the lights before I ride and to be honest I don't recall the last time a bulb failed.

Striker1423 · May 28, 2021, 02:58:02 PM

Quote from: teazer on May 28, 2021, 02:39:05 PM
So if the resistance is low with say an LED bulb, it would probably be on all the time? Was that an optional extra or OEM? I don't recall ever seeing one on a bike and not sure I see the need for one. I always check all the lights before I ride and to be honest I don't recall the last time a bulb failed.

It was standard on the air-cooled RD's. If you look up under the frame tubes where the frame meets the headstock, there should be a small rectangle-shaped box mounted above the horn with a plug that has 3 or 4 wires on it. That's the lamp checker.

1976RD400C · May 28, 2021, 03:41:40 PM

Does your headlight hi/lo and tail light work ok? Do your dash lights come on when you turn the key all the way to "park" position?

Striker1423 · May 28, 2021, 03:59:01 PM

Quote from: 1976RD400C on May 28, 2021, 03:41:40 PM
Does your headlight hi/lo and tail light work ok? Do your dash lights come on when you turn the key all the way to "park" position?

The dash light on the speedometer doesn't light up. I have to check the harness and bulb. The hi/lo and tail light all function as they should. But, yes minus the speedometer lights, the dash lights turn on in park position.

1976RD400C · May 28, 2021, 04:31:59 PM

I think the LED bulb is going to keep the stop light warning light on all the time. Does a regular bulb make it go out?

JB Weld · May 28, 2021, 09:22:31 PM

I have the same problem on my 74 RD350. LED stop/tail/turn and it's flashing or on all the time. I have an LED flasher for the turn signals which works great. I'm sure a resistor might fix the brake light, or just remove the bulb

klaird · May 28, 2021, 09:49:47 PM

The light checker issue has come up before with a LED taillight. Mine did the same thing when I tried using one so I stuck the old bulb back in and forgot it. Later I did find this fix but I haven't tried it.

To eliminate the light checker, unplug the device and jump the yellow to the green/white. This should cause the dash light to illuminate whenever the brake is applied.

Striker1423 · May 30, 2021, 12:07:39 PM

I swapped a standard bulb back in it and the light is still lit at all times.

1976RD400C · May 30, 2021, 03:08:48 PM

Check to see if the yellow wire at the stop light relay is getting +12 volts when you step on the brake. If that yellow wire in not connected to the brake light circuit it will cause the dash warning light to be on all the time.

Hawaii-Mike · May 30, 2021, 03:49:14 PM

Same problem with my Kawasaki H2. I run the incandescent bulb to keep the brake light checker working properly. I tried a Canbus LED brake light, it did not fix the problem.

Striker1423 · June 05, 2021, 04:00:05 PM

I get 12v at The yellow wire when brake is applied. I get 12 constant at the green wire. I'll try jumping it next.

Striker1423 · June 06, 2021, 09:53:12 AM

Jumped it and it stays lit. I think the relay is broke. Unplugged it. No stop lamp of course, so oh well.

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Stop Lamp Checker