Rear Brake/Turn signal issue [left side only]

[JSpa]

What's up fellow Expedition owners? I've been troubleshooting an issue on my 2006 Ford Expedition. The left rear brake/turn signal is working intermittently. It does the standard annoying fast click when it's not working. The right works perfectly fine. Hazard signals work fine as well.

I'm no mechanic but pretty resourceful with google and a wrench. Here are the things that I've tried:

- changed bulb
- swapped right and left bulb mount. Right works fine with either setup, left still has an issue.
- checked fuses and can't seem to find a bad one, left turn signal works sometimes which makes me think it's not a fuse
- changed the turn signal assembly on the steering column
- greased the connections

None of this worked, so I took it to a mechanic. It wasn't a ford dealership but a local mechanic. He didn't charge me but also didn't seem like the type of mechanic that is intimately familiar with Expedition issues.

A few things I believe it could be:

- bad ground [not sure where to find this on my truck]
- BCM [mechanic suggested taking it to Ford to have them fix it]
- wiring issue

Ideally, I can resolve this on my own. Any suggestions? Has anyone had this problem?

Thanks in advance for your input.

 

[riphip]

I would try a pigtail from light ground to body first. Cheap, simple & quick results or not

 

[BlackCoffee]

If you haven't installed LEDs, fast click is caused by low resistance to ground. Left side turn signal and brake, it is the wire to the left turn signal shorting to ground. If it is intermittent, you probably have a chaffed wire that is intermittently contacting the frame. If it doesn't work at all, it is probably shorted. Fast click is the same behavior you get when you install LED lights without a resistor. Check high side resistance to ground.

It doesn't appear to be a bad ground, may be a new corrosion path to ground, but that usually has high resistance. A bad ground or a corrosion path would cause a slow or non-existent blinking. Fast click, working light is the opposite, a short somewhere.

In an extremely rare possibility, remember there are two connectors for the trailer that feed brake lights and turn signals. Don't forget them.

 

[JB1258]

I have a 2004 that we bought brand new and the left side tail and turn light pops s bulb every couple of months.I love for but this has been the worst vehicle I have ever bought that was ford had constant problems with it its a ground going bad