Yet another turn signal/taillight issue (SOLVED!)
06-02-2013, 02:48 PM
#1
Staging Lane
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Yet another turn signal/taillight issue (SOLVED!) As of now I think I'm at least 10 hrs into research, and 8-10 hours into repairs, all for a silly problem but it is getting on my last nerve.
Whenever I use my left turn, all 3 rear lights light up and flash. Both left and right and the 3rd light on the spoiler. All bulbs have been replaced, there is minor corrosion on a couple of the connectors but all bulbs burn bright and true.
I just spent quite a bit of time replacing the turn signal switch inside the steering column (3 times, technically, since Im an idiot), thinking that had the be the issue. NOPE. Same thing still happening, and on top of that, now I have an AIR BAG light on... yeesh. So I've managed to make it worse.
The only other supporting information is that the cruise shuts off whenever I use the left turn as well (recognizing the 3rd brake light I'm imagining), and the hazards work fine all the way around as well...
Ideas?
Specifically I would like a detailed wiring diagram instead of a block diagram if anyone has it, or has had a similar issue. I'll be taking apart the tail lights later to take a look for shorts.
Whenever I use my left turn, all 3 rear lights light up and flash. Both left and right and the 3rd light on the spoiler. All bulbs have been replaced, there is minor corrosion on a couple of the connectors but all bulbs burn bright and true.
I just spent quite a bit of time replacing the turn signal switch inside the steering column (3 times, technically, since Im an idiot), thinking that had the be the issue. NOPE. Same thing still happening, and on top of that, now I have an AIR BAG light on... yeesh. So I've managed to make it worse.
The only other supporting information is that the cruise shuts off whenever I use the left turn as well (recognizing the 3rd brake light I'm imagining), and the hazards work fine all the way around as well...
Ideas?
Specifically I would like a detailed wiring diagram instead of a block diagram if anyone has it, or has had a similar issue. I'll be taking apart the tail lights later to take a look for shorts.
Last edited by Jonota; 07-07-2013 at 11:26 AM.
06-03-2013, 06:51 AM
#2
This is going to take a while to find... (BTW - The full wiring diagrams are in the GM Factory Service Manuals published by Helm.
Is sounds like you have a short between the brake lights and turn signals.
I'd start by u plugging the rear harness behind the hatch carpeting, using an electronic flasher, and then putting on the turn signals. If your third brake light does not flash, then the short is somewhere in the rear harness. If it does flash, then its further inside.
Is sounds like you have a short between the brake lights and turn signals.
I'd start by u plugging the rear harness behind the hatch carpeting, using an electronic flasher, and then putting on the turn signals. If your third brake light does not flash, then the short is somewhere in the rear harness. If it does flash, then its further inside.
06-22-2013, 08:04 AM
#3
Staging Lane
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Went ahead and replaced the front sockets just to take them out of the equation. No dice. So now I need to find those wiring diagrams and get into the harnesses. WEEEEEEEEE!
06-22-2013, 09:51 AM
#4
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Hmmmm....
So I got out the system wiring diagram from a Mitchell pdf here on the site and starting lining out circuits. Then I compared with the wiring that I know of.
My issue is that when the switch is put to the "left" turn position, all rear taillights blink like I'm hitting the brakes on and off. However, the front lights act normally at all conditions, and right turn and stop lights work perfectly.
So then looking at the wiring arrangement, the white wire for the brake light input/3rd taillight is first on the connector, and the next wire is the green for the right rear, and the next wire is the yellow for the left rear. If the yellow and white wires are shorted somewhere, then the left turn signal would feed to the 3rd brake light, which would backfeed to the right taillight since the turn signal switch would have the right taillight setup to receive a brake input, but when the right signal or brake lights were used it would all work normally.
I'm going to start at the steering column at the connector and work my back. I'm not too sure on which harnesses go where, but at some point the 3rd light has to split off, and since it is part of the problem I'm starting from where I know they all are in close proximity.
So I got out the system wiring diagram from a Mitchell pdf here on the site and starting lining out circuits. Then I compared with the wiring that I know of.
My issue is that when the switch is put to the "left" turn position, all rear taillights blink like I'm hitting the brakes on and off. However, the front lights act normally at all conditions, and right turn and stop lights work perfectly.
So then looking at the wiring arrangement, the white wire for the brake light input/3rd taillight is first on the connector, and the next wire is the green for the right rear, and the next wire is the yellow for the left rear. If the yellow and white wires are shorted somewhere, then the left turn signal would feed to the 3rd brake light, which would backfeed to the right taillight since the turn signal switch would have the right taillight setup to receive a brake input, but when the right signal or brake lights were used it would all work normally.
I'm going to start at the steering column at the connector and work my back. I'm not too sure on which harnesses go where, but at some point the 3rd light has to split off, and since it is part of the problem I'm starting from where I know they all are in close proximity.
06-22-2013, 08:02 PM
#5
You are on the right path. The problem is probably up front as you point out. The 3rd light and tail lights split off before they get back to the hatch.
I recall that the brake lights go through the turn signal switch, so the problem might even be there. You should be able to test at the connector at the base of the steering wheel column.
I recall that the brake lights go through the turn signal switch, so the problem might even be there. You should be able to test at the connector at the base of the steering wheel column.
07-07-2013, 11:35 AM
#7
Staging Lane
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Finally got around to tracking down the wiring problem. As I stated in an earlier post, I felt that based on the wiring diagram and symptoms I had a short between the first and third wires coming out of the turn signal switch connector under the steering column. Since I had had the rear taillights off I decided to check out back there real good (I know that the 3rd tail splits before this).
I took everything off, disconnected the main tail connector and applied battery power to each terminal to check everything. Everything was fine (although I needed to replace a backup bulb). I did a short test on the 1st and 3rd wires under the dash with it unplugged, and came back with a positive that they were shorted. So my deduction was correct on that aspect... now to find it.
I figured the first place to start was taking off the side inner interior panel next to the rear seats so I could see most of the wiring run and go from there. I started by pulling the speaker cover... after which I discovered two interesting things.
1) I have no mid/rear speakers.....
2) My "short" was no failure - someone had actually INTENTIONALLY put a splice connector across the two... WTF????
After pulling the splice (it was the cheesy press on metal tab/plastic body splice), everything works PERFECTLY now. But that still leaves me with the question of why in the H3LL someone would intentionally splice two wires together?? Nothing was coming out of it... just the 2 wires, neither cut on either end.... just...weird.
Long story short: the wiring diagram works well to help wittle down the failure possibilities if you use your symptoms and how the system works.
Anyone have any idea why someone would jumper these wires???
I took everything off, disconnected the main tail connector and applied battery power to each terminal to check everything. Everything was fine (although I needed to replace a backup bulb). I did a short test on the 1st and 3rd wires under the dash with it unplugged, and came back with a positive that they were shorted. So my deduction was correct on that aspect... now to find it.
I figured the first place to start was taking off the side inner interior panel next to the rear seats so I could see most of the wiring run and go from there. I started by pulling the speaker cover... after which I discovered two interesting things.
1) I have no mid/rear speakers.....
2) My "short" was no failure - someone had actually INTENTIONALLY put a splice connector across the two... WTF????
After pulling the splice (it was the cheesy press on metal tab/plastic body splice), everything works PERFECTLY now. But that still leaves me with the question of why in the H3LL someone would intentionally splice two wires together?? Nothing was coming out of it... just the 2 wires, neither cut on either end.... just...weird.
Long story short: the wiring diagram works well to help wittle down the failure possibilities if you use your symptoms and how the system works.
Anyone have any idea why someone would jumper these wires???
