Flasher / turn signal problem?
11-15-16, 08:47 PM
#2
My guess is the ground wire for the driver's side lamp is broken. So the marker/city/inner lamp is actually grounding thru the + side of the signal lamp.
Then when the 12V+ shows up to light the signal lamp, that ground path is gone so the marker/city/inner lamp goes out.
This makes sense in a screwed up way. IF the ground wire is bad, for the marker/city/inner lamp, the 12V+ would be present, but the GND is missing. Since the GND wire is shared between this bulb and the signal light on the same side, it manages to ground thru the signal bulb. Then when the signal bulb is "lit" that path becomes 12V+. At this time for the marker/city/inner bulb, both of its wires are now 12V+ so it goes out. The poor signal bulb can't light because it has 12V+ but no GND.
If you wanted to prove my theory easily, turn on the hazard lamps but leave the headlight switch off. In theory, then the signal lamp would be grounding thru the marker lamp. Or if you pull the bulb from the signal lamp, that maker lamp should no longer be able to light up.
If by some miracle my theory is correct, I think you can access the wiring that these plug into by removing the under tray.
Vince
Then when the 12V+ shows up to light the signal lamp, that ground path is gone so the marker/city/inner lamp goes out.
This makes sense in a screwed up way. IF the ground wire is bad, for the marker/city/inner lamp, the 12V+ would be present, but the GND is missing. Since the GND wire is shared between this bulb and the signal light on the same side, it manages to ground thru the signal bulb. Then when the signal bulb is "lit" that path becomes 12V+. At this time for the marker/city/inner bulb, both of its wires are now 12V+ so it goes out. The poor signal bulb can't light because it has 12V+ but no GND.
If you wanted to prove my theory easily, turn on the hazard lamps but leave the headlight switch off. In theory, then the signal lamp would be grounding thru the marker lamp. Or if you pull the bulb from the signal lamp, that maker lamp should no longer be able to light up.
If by some miracle my theory is correct, I think you can access the wiring that these plug into by removing the under tray.
Vince
11-16-16, 02:30 PM
#3
Thanks for the reply Vince!
after some testing last night, it appears no voltage is coming through the green wire (power for the turn signal). Both the flash signal 12v and the parking light 12v signal go to the red wire (parking light bulb) with the shared ground.
i am now wondering if this could be the result of a bad flasher unit.
thoughts?
after some testing last night, it appears no voltage is coming through the green wire (power for the turn signal). Both the flash signal 12v and the parking light 12v signal go to the red wire (parking light bulb) with the shared ground.
i am now wondering if this could be the result of a bad flasher unit.
thoughts?
11-16-16, 08:11 PM
#4
I'm slightly confused by what you are saying, but if you are saying the flashing 12V+ is seen on the park light wire, that should confirm the lack of ground.
The reason you see the 12V+ on the RED/BLACK STRIPE wire from the park lamp is because the park lamp is grounding thru the turn signal bulb. IF the proper ground does not exist, the 12V+ from the park lamp goes thru the common connection on the black wire thru the turn signal bulb thru the RED/BLACK STRIPE wire and eventually hits chassis ground somewhere. THEN when you hit the left signal or hazards, the RED/BLACK STRIPE wire now has 12V+ on it and the park lamp goes out as a result of the ground path being gone.
The battery lamp on most cars works this way too, when the key is on 12V+ is on one side of the battery lamp bulb and it grounds thru the voltage regulator. THEN, when the alternator is on and operating that wire now has V+ on it and the lamp goes out since V+ is on both sides of the bulb. IF the alternator happens to quit while the engine is running, that V+ is gone and the bulb illuminates.
Just to make it clear, these are the wire colors at the driver's side park lamp.
RED/BLACK STRIPE = 12V+ For park lamp
BLACK = GND for both bulbs
GREEN/BLACK STRIPE = 12V+ For turn signal
To make this really easy, with a test light, put your clamp on the positive battery terminal and the probe end in the center terminal (the black wire).
IF it lights, then you have a good ground and can move on.
IF it does not light, you have identified the problem!
Vince
The reason you see the 12V+ on the RED/BLACK STRIPE wire from the park lamp is because the park lamp is grounding thru the turn signal bulb. IF the proper ground does not exist, the 12V+ from the park lamp goes thru the common connection on the black wire thru the turn signal bulb thru the RED/BLACK STRIPE wire and eventually hits chassis ground somewhere. THEN when you hit the left signal or hazards, the RED/BLACK STRIPE wire now has 12V+ on it and the park lamp goes out as a result of the ground path being gone.
The battery lamp on most cars works this way too, when the key is on 12V+ is on one side of the battery lamp bulb and it grounds thru the voltage regulator. THEN, when the alternator is on and operating that wire now has V+ on it and the lamp goes out since V+ is on both sides of the bulb. IF the alternator happens to quit while the engine is running, that V+ is gone and the bulb illuminates.
Just to make it clear, these are the wire colors at the driver's side park lamp.
RED/BLACK STRIPE = 12V+ For park lamp
BLACK = GND for both bulbs
GREEN/BLACK STRIPE = 12V+ For turn signal
To make this really easy, with a test light, put your clamp on the positive battery terminal and the probe end in the center terminal (the black wire).
IF it lights, then you have a good ground and can move on.
IF it does not light, you have identified the problem!
Vince
Last edited by Project88Turbo; 11-16-16 at 08:21 PM.
