Tailight Diode

Geez, just realized I never finished this post with an update. Replacing the diode with new fixed the problem. Cheap-n-easy!

Easy way to verify is the swap the inputs to the suspected diode or swap between a known good diode. It happens.

Also be careful with option 1 setup and if you are using a supplemental braking system on the toad. Depending on how the toad braking system does it's work in may activate the toad's normal brake lights that will over ride the turn signal from the coach. The coach turn signal will still flash but the toad won't since the bulb is getting constant voltage from the toad battery thru the brake light circuit which is normally active ALL the time, even when the key is off. I did option 2 when I wired up a CRV for towing.

rgatijnet1 wrote:
The short answer is yes, the diode can make a difference if it is bad.
Here is a good article about wiring toads that may allow you to figure out how yours was wired and locate the problem. Toad wiring methods

Thank you for the link. It looks like "option 1" was used on my toad.
Looks like a new diode is in my future.

bullydogs1 wrote:
Yes it can...I had it where the brake lights worked but the right turn signal did not...when I touched the diode, it then worked, then I knew to replace the diode.

Good info, thanks. I think it's time to replace that puppy.

Ductape wrote:
Is the turn signal and brake lamp on the car the same lamp? You said the brake light works.

The Toyota yellow turn signal is a separate bulb. My set up uses the brake light bulb which has 2 filiments for braking and turn signal.
The brake light side of things work fine, just the flashing turn signal is absent.

Yes it can...I had it where the brake lights worked but the right turn signal did not...when I touched the diode, it then worked, then I knew to replace the diode.

Is the turn signal and brake lamp on the car the same lamp? You said the brake light works.

Lt46 wrote:
My question is; will a faulty diode cause this?

YES

And in fact I would rate the odds as nearly 100% given the diagnostics you have done.

The short answer is yes, the diode can make a difference if it is bad.
Here is a good article about wiring toads that may allow you to figure out how yours was wired and locate the problem. Toad wiring methods

Yes, a faulty diode can cause your failed turn signal problem. Each light function has its own diode to prevent feedback from the toad to the coach and vice versa. There should be two diodes for that turn signal, one connected to the coach wire, and one connected to the toad wiring, with the other ends both connected to the light bulb.