Right rear blinker works intermittently?

[cheesepuffs]

Hey guys, I have an electrical issue on my hands. My right rear blinker and brake light (same bulb) only work when they feel like it, which is to say maybe 25% of the time. Lights at all other corners are fine, which means the turn signal relay is fine, correct? The blinker stalk works fine. Only when I hit my right blinker it rapidly flashes on the dash and my front turn signal blinks twice as quickly, leading me to believe that there is a short in the wire leading to this bulb.

There are three bulbs in each of my tail lights. One running light, one reverse light, and one blinker/brake light combo which is the light in question. My running light and reverse light on this side work fine. Only this one bulb doesn't light. Nothing. Replaced the bulb and the problem persists.

So what's my best course of action? Where are the most obvious places to test? I have a multimeter, but what do I do? Just try pull this one wire out of the frame (wires are on the inside of the drivers side framerail and are very hard to get to) and then visibly check for a nick in the wire until I find something? Is there anything else it could be?

 

[old1]

I would suspect a bad ground on the non working bulb

 

[yonyon]

Examine the bulb socket before you start worrying too much about the wiring.

 

[NMBurb02]

Sounds like you're low on blinker fluid.

 

[Chris142]

X2 on cleaning the socket

 

[cheesepuffs]

Originally Posted By: yonyon
Examine the bulb socket before you start worrying too much about the wiring.


Originally Posted By: Chris142
X2 on cleaning the socket


Ok so after some Googling I must say that I have never heard of bulb grease before but it definitely has bulb grease in all three of the sockets in this tail light assembly. Dark yellowish-tan substance. There was no moisture in my tail light so I don't suspect that water is causing this. The plug-in connection for the lights is clean and in good shape. Could it be that this one bulb terminal is bad?

I'm gonna try to test with a multimeter tomorrow. Hoping I can replace the circuit board instead of chasing a short somewhere in the frame...

 

[cheesepuffs]

So as an update I replaced the circuit board in the light assembly and that didn't fix it even though I'd getting voltage through the hardness connection. Very confused at this point...

 

[yonyon]

How did you check for voltage at the harness connector? Ideally, you should check with a voltmeter backprobing the connector while it's plugged in and the bulb installed. If you use a test light it needs to be one that uses a serious bulb not one of those milliamp test lights or the kind with an LED.

If you have a poor connection in the wiring you can have plenty of V at the connector while it's unplugged and then hardly anything with the load/bulb connected.

 

[cheesepuffs]

I used a multimeter and did probe the wires coming into the connector while it's plugged in. It shows that I'm getting power into the hot wire to the blinker/brake light but there is no voltage in the ground wire with the blinker on. Which is strange because there are two other bulbs run with this same connector (tail running light and reverse light) and they both work fine. If the ground wire on the plug/harness was bad then wouldn't none of these work at all?

It's not the turn signal switch because I'm getting proper voltage for it at the connector/harness plug. And the bulb is known good.

 

[yonyon]

I'm pretty sure all three bulbs use the same black wire at the end of the connector for their ground.

If you're losing your ground there when you turn the bulb on that sounds like there's a bad connection and it can't handle the amps. Does the tail light dim when you shift into reverse?

 

[yonyon]

The ground point should be at a bolt with maybe a few other grounds on it as well right there at the back of the truck. There should be only 1 splice, also right around there, inline between the connector and the ground point so at least it won't be that hard to trace out.