CHMSL, 3RD Brake light inop.

[Dginn69]

Hello, all. I replaced the gasket for my 3rd brake light today on my 09. Upon checking after I reassembled I noticed the bed lights work but not the brake light. I tried swapping one of the bed light bulbs with the non working brake light. The cab lights still work and no brake light.
So I go under the hood and swap the 15A fuse from my interior light to the CHMSL #27. And the interior lights still work and still not brake light.
So what should I check next? I get no dash indicator that a brake light is out like I did when the right brake light went out. I am not even sure the system monitors the 3rd brake light.
Any help will greatly be appreciated. Thanks in advance.

p.s I did not check if the 3rd brake light worked prior to replacing the gasket. I wish I had. So I am unsure how long it was out.

 

[BossHogg]

Not much left to check outside of the connector on the third brake light.

 

[jawzs2]

On my 2010, the third brake lights doesn't work with the key off, needs to be on\running.

 

[Rlaf75]

May be a stupid question but are you checking it with the key on or truck running? I don't believe the brake lights will work unless it's running. If it's running then start checking the bulb socket for damaged contacts and for power. If no power then check the connector for power

 

[Dginn69]

On my 2010, the third brake lights doesn't work with the key off, needs to be on\running.

Yes the truck is running.

 

[Dginn69]

May be a stupid question but are you checking it with the key on or truck running? I don't believe the brake lights will work unless it's running. If it's running then start checking the bulb socket for damaged contacts and for power. If no power then check the connector for power

No its not a stupid question. I do have the truck running.

 

[Dginn69]

Not much left to check outside of the connector on the third brake light.

Do those connectors go bad often? I am going to open it back up today and check with a multi meter.

 

[chopperman1]

Have you checked voltage? Backprobe the bulb socket.

 

[turkeybird56]

YUP, check for voltage at socket. Also use volt meter and confirm voltage at fuse point in TIPM. So if U have voltage at TIPM, but not at socket, then a wire issue. But also do not just check the socket, also check the wiring directly in front of socket as may just be a bad socket.

ADDED: Now U know, if U got power at socket, maybe another bad bulb, not be the 1st time, if dual connector on bulb, I am not sure if there is a polarity issue or not on socket (ie., bulb goes in one way ref contacts)

 

[jawzs2]

Yes the truck is running.

If you do have a power issue, this may help diagnose it. There is a link to the complete 2009 service manual with wiring diagrams. It works best if you copy the link and paste it in a new window.

2012 Trailer Wiring issue

Hey guys, I’ve searched everywhere and nothing for a 2012 issue that I have. Left side/brake lights not working on trailers. All fuses good. From what I gather, I need to check the power coming from the TIPM. Does anyone know what connector/wire I should hook the test light up to? There was one...

www.ramforum.com

 

[Rlaf75]

No its not a stupid question. I do have the truck running.

I had to ask because you never know. Anyway, pull the bulb out and check the socket for power. Make sure the contacts are not bent or broken. If I remember correctly it's a 195 or 921 bulb and the bulb socket has 4 contacts in it. They can over time get corroded and break. They can also get bent if not careful when reinstalling the bulb causing them to not make a good contact. Start with the basics

 

[Dginn69]

YUP, check for voltage at socket. Also use volt meter and confirm voltage at fuse point in TIPM. So if U have voltage at TIPM, but not at socket, then a wire issue. But also do not just check the socket, also check the wiring directly in front of socket as may just be a bad socket.

ADDED: Now U know, if U got power at socket, maybe another bad bulb, not be the 1st time, if dual connector on bulb, I am not sure if there is a polarity issue or not on socket (ie., bulb goes in one way ref contacts)

This is what I did today. I check the fuse for continuity and it was good. I checked the fuse socket on it was sending juice and the socket had 13v. So I went & bought new bulbs and it works. I am not sure why the one I swapped didn't works. But at least it's working.

 

[jawzs2]

Glad it was that simple

 

[turkeybird56]

This is what I did today. I check the fuse for continuity and it was good. I checked the fuse socket on it was sending juice and the socket had 13v. So I went & bought new bulbs and it works. I am not sure why the one I swapped didn't works. But at least it's working.

Comes under 2 Titles:
1) Murphy got U
2) Chit happens.

Fortunate it was that simple. Be safe,.

DA BOIRD..

 

[Dginn69]

I had to ask because you never know. Anyway, pull the bulb out and check the socket for power. Make sure the contacts are not bent or broken. If I remember correctly it's a 195 or 921 bulb and the bulb socket has 4 contacts in it. They can over time get corroded and break. They can also get bent if not careful when reinstalling the bulb causing them to not make a good contact. Start with the basics

I checked the socket and had power. I bought a new bulb and it works. For some reason when I switched the bulbs from the bed lights (same 921 bulb) the one I swapped to the brake light position did not work. And the one from the brake position worked in the bed light socket.

 

[turkeybird56]

I checked the socket and had power. I bought a new bulb and it works. For some reason when I switched the bulbs from the bed lights (same 921 bulb) the one I swapped to the brake light position did not work. And the one from the brake position worked in the bed light socket.

Don't beat yerself up. U got it working, all good. MURPHY always there, sometimes an issue.

 

[Dginn69]

Glad it was that simple

Me too! I hate troubleshooting electrical issues. I still dont know why that bulb I switched from the bed lights did not work. BUt who cares its working. And I fixed the leaky 3rd brake light.

 

[BossHogg]

I went & bought new bulbs and it works. I am not sure why the one I swapped didn't works. But at least it's working.

Yet another example of new does mean working. I've been bit a few times making the assumption that brand new means it works.

 

[Dginn69]

Yet another example of new does mean working. I've been bit a few times making the assumption that brand new means it works.

I definitely agree, but it worked in the bed light socket & not the 3rd brake light socket.