Left Turn Signal Issues, Lights Up Brake Lamps

[CamaroDave]

A few days ago my left turn signal stopped working (the right signal still works fine). What's odd is the left signal will light up if I press the brake pedal, but signal won't flash. So today I was checking a few things like the bulbs, fuses, and relays which all check out ok. After some futzing around with the turn signal lever, I can get the left signal to flash like it works normal but now the brake lamps flash with the blinker. Then if I press the brake pedal the left signal stays lit but doesn't flash.

 

Based on the other threads I've searched through I'd guess it's the multifunction switch, but I'm open to suggestions. Let me know if you need more info.

 

Thanks,

Dave

[CamaroDave]

Ok, so I did some more poking around and here is what I found. At the fuse block, the right signal fuse will give me a constant 12v when the right turn signal is engaged (which makes sense). The left side gives an inconsistent and sporadic 5-12v when the left signal is engaged. The other really odd thing is that after I pulled both left and right signal fuses, the right signal and relay is completely dead but when I click the left signal the relay clicks as if the blinker works normal.

 

I'd like to rule out as much as possible before I spend $120+ on a new turn signal switch so I'm open to any suggestions.

 

Thanks.

[minibike132]

From your first post I'd guess multifunction switch. If you want more than a guess give me till tomorrow (it's time for bed) and I'll look over the diagrams to address the second post questions. Please do I like it when someone is willing to do some testing and not want a guess.

[CamaroDave]

I'm all ears! Please let me know what else you find out. Thanks.

[Zembonez]

I'm also going to say the turn signal / combo swhtch is going bad. It is not an uncommon problem on a lot of vehicles.

 

Let's see what "sparky" comes up with.

[CamaroDave]

I'm also going to say the turn signal / combo swhtch is going bad. It is not an uncommon problem on a lot of vehicles.

 

Let's see what "sparky" comes up with.

 

 

I'm still leaning towards the turn signal switch too just for the fact that the turn signal will come on if I feather the signal lever.

 

I'm at work now and a co-worker suggested checking out the trailer/tail light wiring harness above the fuel tank below the bed. I checked out the harness at the rear bumper but didn't know there was one above the fuel tank. I'll post any updates later tonight.

[minibike132]

I'm also going to say the turn signal / combo swhtch is going bad. It is not an uncommon problem on a lot of vehicles.

 

Let's see what "sparky" comes up with.

 

 

What I came up with is a freaking headache from looking at diagrams all day (not just yours, it was a heavy electronic day for me) there are something like 20 diagrams for exterior lamps on an 03k truck, and that doesn't include headlamps. I'm glad I looked though, this system doesn't work like the ones that we automatically condemn the multifunction switch. Long story short I would replace the turn signal flasher module and stay away from the turn signal switch. I can't positively explain what happened when you removed the fuses or the voltages you got. If it was in my bay I could but it's not and the diagrams do not show what goes on inside the module. It sould look like a long relay (12 pins) and it's on the back side of the left IP fuse panel (you said you can hear it, looks like it's there. If I was looking at this thing I would pull it out and probably just replace it unless I was slow and was curious as to what is going on inside there. Doing that kind of testing would take me forever to type out and I'm not going to bother unless you replace the flasher and it doesn't fix the problem. I can't say that I can remember replacing one but I think if you took off the lower hush panel and maybe the knee bolster you can get at that module from the back without removing the fuse block. I would recommend against removing the fuse block if you don't have to because doing so makes it likely that you would dammage some terminals on the block and that is trouble that you do not want at home. Good luck and let me know what you find out or decide to do.Edit: I got all wrapped up in what you checked in the second post, from the first post I still lean on the switch. Let me know if you have a voltmeter handy and want to check the switch to be positive that it is or is not the switch.

[CamaroDave]

sparkstech: Thanks for the reply. Your post has me thinking about the flasher/signal relay again. I know exactly where you are talking, and I did have it apart last night. I'm fairly competent when it comes to mechanical and electrical systems so I took the relay module out and popped the cover off. With the cover off and the unit plugged in both relays (left and right signals) work "normal", at least to my visual inspection. However, it's not unreasonable to think this module still may be at fault.

 

With all this being said, I'd still like to check as much as possible so if you have a procedure to check the turn signal switch, then please let me know. I have a digital multi-meter and unless it snows, I can continue to drive my Camaro everyday.

[minibike132]

Access the turn signal switch connectors (there should be a couple) on one of the connectors terminal A should be light green and terminal C should be dark green. Turn signal on right you should have 12 volts at terminal A, turn signal left you should have 12 volts at terminal C. You should have no voltage at either terminal with the switch in the off state. If you have this you can safely say the multifunction switch is not your problem.

[CamaroDave]

Access the turn signal switch connectors (there should be a couple) on one of the connectors terminal A should be light green and terminal C should be dark green. Turn signal on right you should have 12 volts at terminal A, turn signal left you should have 12 volts at terminal C. You should have no voltage at either terminal with the switch in the off state. If you have this you can safely say the multifunction switch is not your problem.

 

 

Well I ended up checking this late last night and found 12v at both terminals respectively. I even got the left signal to not work when I engaged the lever and found 12v so the multi-function switch is ruled out.

 

Looks like all signs now point to the flasher relay module. Unfortunately this unit is $100 and there is no recall for my truck, even though there is a recall for the 2003 Envoy. I'll let you know how I make out with the new module.

 

Thanks again for the help!

[6chevelle9]

Access the turn signal switch connectors (there should be a couple) on one of the connectors terminal A should be light green and terminal C should be dark green. Turn signal on right you should have 12 volts at terminal A, turn signal left you should have 12 volts at terminal C. You should have no voltage at either terminal with the switch in the off state. If you have this you can safely say the multifunction switch is not your problem.

 

 

Well I ended up checking this late last night and found 12v at both terminals respectively. I even got the left signal to not work when I engaged the lever and found 12v so the multi-function switch is ruled out.

 

Looks like all signs now point to the flasher relay module. Unfortunately this unit is $100 and there is no recall for my truck, even though there is a recall for the 2003 Envoy. I'll let you know how I make out with the new module.

 

Thanks again for the help!

 

 

 

Camarodave, I have 05 and my friend as an 05 we had to replace both of them... Samething, my left turnsignal for my trail lights stopped working and tracing out the wires/diagrams it lead me to the module... You are right ~$100.00 ..Good luck .

[CamaroDave]

UPDATE! A co-working and I swapped the flasher relay module and with mine in his '03 Silverado it produces the same symptom! Ironically he was having problems with his left trailer brake light and my module fixed it....looks like we killed two brids with one stone. I ordered the part from gmpartsdirect for ~$60 shipped and it should be here on Wednesday.<br><br>Thanks again for everyone's comments/suggestions especailly sparkstech!

[minibike132]

I'm glad we could help.

[Zembonez]

I'm glad we could help.

Excellent Dave!

 

Thanks for posting the update for our future reference. Most of the time we never know what ended up fixing the problem.

 

Come back and shoot the breeze with the zoo.

[CamaroDave]

I'm glad we could help.

Excellent Dave!

 

Thanks for posting the update for our future reference. Most of the time we never know what ended up fixing the problem.

 

Come back and shoot the breeze with the zoo.

 

Also for reference the part # for the flasher module is: 10383321 which is a replacement from the original module and p/n. I would have posted that sooner but I'm getting over a cold and haven't been online much.