persistent problem with turn signals
11-03-2005, 06:58 AM
#1
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persistent problem with turn signals Recently, my left front directional signal stopped flashing, so I changed the bulb... the socket was nasty, but worked... for a couple weeks, then the blub blew again. So, I purchased a socket and replaced it... it flashed twice and blew again.
(And as a side note, what idiot engineer mounts the bulb from the bottom of the lense when the back is just as accessible, and gravity won't aide the accomulation of moisture on the electrical contacts!!)
Anyway, I pulled out the socket and bulb and tested them, and they BOTH worked fine. So I went for my fuses, and found one marked tail lights (go figure, since this is a front light) was blown, so I changed it. Still nothing. I disembled the entire front wiring, and everything checked out fine. Now mind you, both the dim and bright sides of the bulb would light for Daytime Driving Lights (they are bright if the headlights are off, but dim when you turn the headlights on) so I know that the socket worked and the blub was getting power. But still no directional signal on the left side front... the right side works fine! And the back left come on and stay on, just like the dash indicator. So, I pulled the flasher anyway and tried one for a friend's car just in case... no difference.
When I called my local Pontiac service department, they told me to bring in the car as it might be either a bad directional signal switch or headlight switch (why not, everything else checked out.), But the only way to check it would be to replace it. Of course, as soon as I post my car for sale this becomes a problem... damn Murphy and his laws!
Any thoughts? Anyone else had this problem? Which one is it likely to be, and I'll just change it myself.
Thanks, Bob
(And as a side note, what idiot engineer mounts the bulb from the bottom of the lense when the back is just as accessible, and gravity won't aide the accomulation of moisture on the electrical contacts!!)
Anyway, I pulled out the socket and bulb and tested them, and they BOTH worked fine. So I went for my fuses, and found one marked tail lights (go figure, since this is a front light) was blown, so I changed it. Still nothing. I disembled the entire front wiring, and everything checked out fine. Now mind you, both the dim and bright sides of the bulb would light for Daytime Driving Lights (they are bright if the headlights are off, but dim when you turn the headlights on) so I know that the socket worked and the blub was getting power. But still no directional signal on the left side front... the right side works fine! And the back left come on and stay on, just like the dash indicator. So, I pulled the flasher anyway and tried one for a friend's car just in case... no difference.
When I called my local Pontiac service department, they told me to bring in the car as it might be either a bad directional signal switch or headlight switch (why not, everything else checked out.), But the only way to check it would be to replace it. Of course, as soon as I post my car for sale this becomes a problem... damn Murphy and his laws!
Any thoughts? Anyone else had this problem? Which one is it likely to be, and I'll just change it myself.
Thanks, Bob
11-08-2005, 09:19 AM
#3
Interesting problem. You have a lazy dealer - there are many ways to diagnose problems like this without just replacing parts (but they're not as profitable I guess).
OK, the first thing to check is the really simple stuff. You already know that the bulb and new socket are good because both the parking lights (low intensity) and DRLs (high intensity) work. We know it's not the flasher even if you hadn't tried another one because both sides run off the same flasher and the right side is working. A burned out bulb is the most common cause of your symptoms - but it doesn't have to be a front bulb. Two things you can check... First, turn on your hazard flashers and walk around the car looking for a bulb not flashing. Don't forget that you should have two flashing bulbs on each side at the back and that the front side marker lamps should flash as well. Second, turn on the headlights so that the front running lamps are dimly lit then try the left turn signal and check if the bright filament lights up. This would indicate that the turn signal is getting power and lighting the bulb but just not flashing.
Now, if you're still with me it's because you've checked all those things and still have the problem so we have to dig deeper. Your dealer was half correct - it could be the turn signal switch but it couldn't be the headlight switch (it's not involved in the turn signal circuit). It could also be the DRL module. You can test these possibilities at the DRL module. Remove the radio and you will find the DRL module mounted to the defroster duct behind the radio to the right of the opening. It is a black box about the size of a pack of cigarettes with two 8-pin connectors (one black and one blue). You're going to want to use a test light with a sharp point so that you can check outputs with the connector still attached to the module. Turn on the ignition and the left turn signal. Check that you get power at the light blue with white wire in the black connector. If so then the turn signal switch is working properly. Next, test for power output at the light blue wire (no white stripe) - also in the black connector. If not then the DRL module is faulty and should be replaced. You can confirm this by unplugging the black connector and shorting the light blue with white wire to the light blue wire to see if this makes the turn signals work (in other words, bypassing the DRL module). Note that in both cases this power would normally be flashing but we've already established that yours don't flash so we just want to check continuity.
If you don't get power on the light blue with white wire at the DRL module then you should suspect the turn signal switch. You can test this at connector C216 which is an 11-pin black single-row connector at the base of the steering column. With the ignition and left turn signal on, check that you have power in the purple wire (this is the power input to the switch from the flasher). Then check for power in the light blue with white wire (this is the left signal output from the switch). If you have power going in but not coming out then you can safely assume that the switch is faulty. We know you will have power going in (on the purple wire) because we know the right side signals work.
OK, the first thing to check is the really simple stuff. You already know that the bulb and new socket are good because both the parking lights (low intensity) and DRLs (high intensity) work. We know it's not the flasher even if you hadn't tried another one because both sides run off the same flasher and the right side is working. A burned out bulb is the most common cause of your symptoms - but it doesn't have to be a front bulb. Two things you can check... First, turn on your hazard flashers and walk around the car looking for a bulb not flashing. Don't forget that you should have two flashing bulbs on each side at the back and that the front side marker lamps should flash as well. Second, turn on the headlights so that the front running lamps are dimly lit then try the left turn signal and check if the bright filament lights up. This would indicate that the turn signal is getting power and lighting the bulb but just not flashing.
Now, if you're still with me it's because you've checked all those things and still have the problem so we have to dig deeper. Your dealer was half correct - it could be the turn signal switch but it couldn't be the headlight switch (it's not involved in the turn signal circuit). It could also be the DRL module. You can test these possibilities at the DRL module. Remove the radio and you will find the DRL module mounted to the defroster duct behind the radio to the right of the opening. It is a black box about the size of a pack of cigarettes with two 8-pin connectors (one black and one blue). You're going to want to use a test light with a sharp point so that you can check outputs with the connector still attached to the module. Turn on the ignition and the left turn signal. Check that you get power at the light blue with white wire in the black connector. If so then the turn signal switch is working properly. Next, test for power output at the light blue wire (no white stripe) - also in the black connector. If not then the DRL module is faulty and should be replaced. You can confirm this by unplugging the black connector and shorting the light blue with white wire to the light blue wire to see if this makes the turn signals work (in other words, bypassing the DRL module). Note that in both cases this power would normally be flashing but we've already established that yours don't flash so we just want to check continuity.
If you don't get power on the light blue with white wire at the DRL module then you should suspect the turn signal switch. You can test this at connector C216 which is an 11-pin black single-row connector at the base of the steering column. With the ignition and left turn signal on, check that you have power in the purple wire (this is the power input to the switch from the flasher). Then check for power in the light blue with white wire (this is the left signal output from the switch). If you have power going in but not coming out then you can safely assume that the switch is faulty. We know you will have power going in (on the purple wire) because we know the right side signals work.
11-08-2005, 02:34 PM
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Many thanks First off, GREAT answer. This is the type of info I needed, as the "easy" fix didn't seem to work. I replaced the bulb, and then the socket, and have power to both sides of the bulb, so I needed more indepth info.
Second, I will have to check this again, but I'm hoping that I didn't miss a bulb in my walk-around check. I did check the bulbs at night with the hazards on, but I didn't notice if either front side marker lamps lite while the hazards were on. I also thought that there were 3 bulbs in the back that illuminated for the hazards. So, I am going to check this all more thoroughly before I pull the radio and check the DRL module.
Also, in trying to figure SOMETHING, ANYTHING out about this problem I studied the blubs again yesterday in the light and dark, and I noticed that the left side (with new bulb and socket) shines much brighter than the right side. I have replaced the bulb on the right side (since they come in pairs) but I haven't replaced the socket. Someone posted on another thread that they had a similar problem as mine. This occured when the person cleaned only one socket, but when he cleaned the other side then both sides started working again. Does this make any sense? Or would you guess it was just a coincidence? ()
Thanks again for all your info. And as these cars are getting older, and it seems that this problem is reoccuring, maybe there should be a sticky with this info. And the name should be: turn signal, blinker, directional, DRL (so almost any search could find it!!
Originally Posted by WhiteBird00
Two things you can check... First, turn on your hazard flashers and walk around the car looking for a bulb not flashing. Don't forget that you should have two flashing bulbs on each side at the back and that the front side marker lamps should flash as well. Second, turn on the headlights so that the front running lamps are dimly lit then try the left turn signal and check if the bright filament lights up. This would indicate that the turn signal is getting power and lighting the bulb but just not flashing.
Also, in trying to figure SOMETHING, ANYTHING out about this problem I studied the blubs again yesterday in the light and dark, and I noticed that the left side (with new bulb and socket) shines much brighter than the right side. I have replaced the bulb on the right side (since they come in pairs) but I haven't replaced the socket. Someone posted on another thread that they had a similar problem as mine. This occured when the person cleaned only one socket, but when he cleaned the other side then both sides started working again. Does this make any sense? Or would you guess it was just a coincidence? ()
Thanks again for all your info. And as these cars are getting older, and it seems that this problem is reoccuring, maybe there should be a sticky with this info. And the name should be: turn signal, blinker, directional, DRL (so almost any search could find it!!
Last edited by ramairbrc; 11-08-2005 at 02:59 PM.
11-08-2005, 02:55 PM
#5
The two sides are not directly related to each other (i.e. they are completely separate circuits from the DRL module forward and have separate grounds) but it's quite possible that corrosion in the remaining original socket is increasing the resistance and so decreasing the current and brightness of that bulb compared to the one with the new socket.
11-08-2005, 06:39 PM
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I've had the same problem. All electrical seems to be working fine, but I always get a blown bulb. My problem is probably different (not to hijack thread) but I've seen a little condensation in the signals. Maybe I have to find a better way to seal these things.
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11-09-2005, 12:20 AM
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Originally Posted by shortdo99
I've had the same problem. All electrical seems to be working fine, but I always get a blown bulb. My problem is probably different (not to hijack thread) but I've seen a little condensation in the signals. Maybe I have to find a better way to seal these things.
11-11-2005, 10:50 AM
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Originally Posted by WhiteBird00
It could also be the DRL module. You can test these possibilities at the DRL module. Remove the radio and you will find the DRL module mounted to the defroster duct behind the radio to the right of the opening. It is a black box about the size of a pack of cigarettes with two 8-pin connectors (one black and one blue). You're going to want to use a test light with a sharp point so that you can check outputs with the connector still attached to the module. Turn on the ignition and the left turn signal. Check that you get power at the light blue with white wire in the black connector. If so then the turn signal switch is working properly. Next, test for power output at the light blue wire (no white stripe) - also in the black connector. If not then the DRL module is faulty and should be replaced. You can confirm this by unplugging the black connector and shorting the light blue with white wire to the light blue wire to see if this makes the turn signals work (in other words, bypassing the DRL module). Note that in both cases this power would normally be flashing but we've already established that yours don't flash so we just want to check continuity.
If you don't get power on the light blue with white wire at the DRL module then you should suspect the turn signal switch. You can test this at connector C216 which is an 11-pin black single-row connector at the base of the steering column. With the ignition and left turn signal on, check that you have power in the purple wire (this is the power input to the switch from the flasher). Then check for power in the light blue with white wire (this is the left signal output from the switch). If you have power going in but not coming out then you can safely assume that the switch is faulty. We know you will have power going in (on the purple wire) because we know the right side signals work.
If you don't get power on the light blue with white wire at the DRL module then you should suspect the turn signal switch. You can test this at connector C216 which is an 11-pin black single-row connector at the base of the steering column. With the ignition and left turn signal on, check that you have power in the purple wire (this is the power input to the switch from the flasher). Then check for power in the light blue with white wire (this is the left signal output from the switch). If you have power going in but not coming out then you can safely assume that the switch is faulty. We know you will have power going in (on the purple wire) because we know the right side signals work.
Once it was free from it's mounting it was EASY too test. Guess what... I found I had power at the light blue with white wire in the black connector, but no power output at the light blue wire (no white stripe). I found that besides "Turn on the ignition and the left turn signal" I also needed to turn on the headlights so that there was no power feeding back from the output wires. I noticed on both the right and left high power output wires had power unless I turned the highlights on.
Whitebird, I really appreciate the help... and as I said early in this post, this might need to be a sticky as many members are reporting such problems as our cars are aging.
Last edited by ramairbrc; 11-11-2005 at 10:56 AM.
11-11-2005, 11:01 AM
#10
Yep, you're right - I forgot that the two turn signal relays built in to the DRL module are used to switch the power from constant (DRL) to flashing (turn signals). That's why there would be power on the light blue wire with the ignition on. Turning on the headlights eliminates the DRL power source and lets you test the turn signal. Good catch!
11-11-2005, 10:28 PM
#11
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Great info. That was the problem, and now all is better. Before I changed the DRL module I changed out the other front socket, as it was looking bad too. I also changed both front lenses, AND I drilled two holes in each, at the front corners.
This has been some adverture. I hope I don't have to do it again!
This has been some adverture. I hope I don't have to do it again!
03-06-2011, 09:34 PM
#12
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Marker light socket Does anyone know of a place that sells the front marker light socket? tried auto zone with no luck.Also if your getting moisture into your marker lights check out autotrix.net,they sell better gaskets.I bought the gaskets but one of my sockets is really rusty,so I figured to replace both sides.Any help would be appreciated.
