Headlight fault help

jdbecks · 11-16-2009, 03:41 PM

symptom;

Turn dipped headlights on and my full beams come on, and the full beam indicator light on the dash illuminates, through out this I do not get dipped beams.

What I have tested:

Checked fuses, all ok
Bridged the relay, still the same
checked voltages at the bulb holders, ok
checked the bulbs, ok
changed over the stalk, still the same problem ( unless the other stalk i have also is faulty, which is unlikely)

Now, I did buy a replacement stalk from an earlier revision mr2, still the same problem. I even stripped down the indicator stalk and fitted it to my whole unit and the same problem also. Unless the stalk was also faulty which I do not believe it is, there must be another problem. Would a bad earth do this do you think?

heres the wiring diagram, its for the US model but I suspect its the same. unless someone has a JDM wiring diagram for the headlights?

1991 MR2 BGB Online - Electrical

CJMR2T · 11-16-2009, 04:01 PM

Did the problem arise out of no where (i.e. one day they are working properly and the next, they are not)? or what?

Need more details of when or how the problem started...

jdbecks · 11-16-2009, 05:03 PM

hi mate, yeah..one evening I got in my car, turned my headlights on and there was nothing. both at exactly the same time, there was no rain or anything either.

CJMR2T · 11-16-2009, 07:23 PM

Ok, so let me get this straight, if you turn on the headlights, you do not get dipped beams with the switch in the dipped beam position but if you flip the switch to Full beams, you do get full beams?

jdbecks · 11-17-2009, 02:56 AM

if I turn my switch to the dipped postion I do not get dipped head lights, I get full beams and the full beam indicator light inluminates on the dash,

My flash deos not work either, so if I pull the stalk to me to flash, nothing happens..although the lights do pop up, but the lights are not on.

CJMR2T · 11-17-2009, 02:54 PM

Im guessing that if you push the switch away (normal activation for full beams) you get nothing?

This really makes no sense... Is there anything that was done in the past that you know of that the headlight wiring (be it dipped beam or full beam) was tapped into or altered like fog lights or driving lights that are wired to activate with a particular beam???

jdbecks · 11-17-2009, 03:52 PM

cancel my last, the flasher and full beam deos work.

Im just getting full beam lights on when my switch is selected for dipped, with the indicator light on the dash for full beams coming on.

CJMR2T · 11-17-2009, 04:24 PM

Ok... so you get full beams with the switch in the dipped beam position, but what happens when you have the switch in full beam position??? No lights at all or still full beams???

jdbecks · 11-17-2009, 06:59 PM

when its at full beam postion, i still have full beams

CJMR2T · 11-17-2009, 07:35 PM

Chances are that you have a short in the wiring being that you've tried differnt switches....

If it were me, I would unplug the harness plug and check both side just to make sure...

Assuming that the wiring is the same for ya'll as it is for the US spec cars, unplug the black 14pin connector that connects the combination switch harness to the dash harness.

Starting with the switch harness side, turn the headlight switch fully on and the beam selector to dip beam position. Make sure that you have continuity between Pin 3 and pin 9 and no continuity between pin12 and pin 9. After that you can flip the switch to the full beam position and you should have continuity between pin12 and pin9 and no continuity between pin 3 and pin 9

summery,

headlight switch fully on.
dip beam position = continuity between pin 3 and 9 only
full beam position = continuity between pin 12 and 9 only.

If you have continuity in on both at the same time then the switch is shorted.

Now for the dash harness side, jump the headlight relay so you will supply power to the lights without the switchs being hooked up. if you short pin 3 to ground, you should have dip beams on only and if you short pin 12 to ground, you should have only full beams on. If you get full beams with either pin shorted, then the two wires are short together somewhere in the harness most likely...

On other thing you can try as I have seen this happen once. Try un hooking one of the headlights and see if the other starts working normally. If it doesnt, then try hooking that one back up and un hooking the other and see if it starts working normal.... I say this cause I have once seen this exact problem and the short was actually in the filaments of the bulb. One filament broke and shorted to the other those cause both beams to become alive any time the headlights were on...

hope all this helps...

jdbecks · 11-18-2009, 10:50 AM

Hi mate,

Ive not been able to test this just yet, however, I would just like to add, when I use the flasher, the lights do not illuminate but the dash light deos come on ( pulling the stalk to the driver, to flash main beams)

CJMR2T · 11-18-2009, 11:53 AM

Quote:

Originally Posted by jdbecks

My flash deos not work either, so if I pull the stalk to me to flash, nothing happens..although the lights do pop up, but the lights are not on.

Quote:

Originally Posted by jdbecks

cancel my last, the flasher and full beam deos work.
.

Quote:

Originally Posted by jdbecks

Hi mate,

Ive not been able to test this just yet, however, I would just like to add, when I use the flasher, the lights do not illuminate but the dash light deos come on ( pulling the stalk to the driver, to flash main beams)

So do they or dont they work? one post you say they dont, the next you say they do, then later going back to saying they dont....

jdbecks · 11-18-2009, 12:20 PM

my apologies, I tested them tonight and they don't work.

CJMR2T · 11-18-2009, 03:45 PM

Ok, to summerize the whole thing, dimmer switch in either dip or full position gives you full beams with the indicator light on too. Flash position give no lights at all but does illuminate the indicator light?

This still leaves us with a short somewhere. Now why you dont get any light at all when in the flash position but you do get indicator really screws this up... It makes no sense unless right hand drive cars are wired differently.... I really dont see this being the case though....

I guess still the only way to tell whats up is to test the individual parts like listed above...

jdbecks · 11-18-2009, 04:00 PM

Quote:

Originally Posted by CJMR2T

Ok, to summerize the whole thing, dimmer switch in either dip or full position gives you full beams with the indicator light on too. Flash position give no lights at all but does illuminate the indicator light?

This still leaves us with a short somewhere. Now why you dont get any light at all when in the flash position but you do get indicator really screws this up... It makes no sense unless right hand drive cars are wired differently.... I really dont see this being the case though....

I guess still the only way to tell whats up is to test the individual parts like listed above...

Yep thats correct, I dont think they are wired any different either. I will check all the what you have said, and will post back, it probley wont be untill Saturday now, Thankyou for your help and sorry about the confusion

CJMR2T · 11-18-2009, 04:10 PM

The biggest thing that is really confusing me with the way toyota wired the system is that according to the riding diagram, the full beam indicator is pulling from the dipped beams...

The only thing that I can think of is that the its a circuit based on current flow resistance (i.e. when in dipped position, the path of least resistance to ground is through the switch so indicator will not light. When switch is in full beam position, there is still currrent flowing through the low beam side but the only flow path to ground is through the indicator light thus lighting it. This current must be very low to not light the dipped beams)... Seems kinda like a rather odd way to wire it unless there is something that Im missing.....

When the headlamp relay is on, both the dip and full beam circuits are hot but the switch determines which circuit is open and which is closed to ground. A short between the two circuits would allow both to be closed when the switch is in either position (full or dipped).....

Now why in flash position, neither are closed doesn't make sense....

Im beginning to think that it is in the switch itself and its a combination of two problems a short and a broken / perminittly opened circuit.

The only problem with my theory is that its hard to believe that two different switches have the identical same two faults.....

11-16-2009, 03:41 PM	#1 (permalink)
jdbecks No Skills Join Date: Aug 2008 Location: England Posts: 33 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Headlight fault help symptom; Turn dipped headlights on and my full beams come on, and the full beam indicator light on the dash illuminates, through out this I do not get dipped beams. What I have tested: Checked fuses, all ok Bridged the relay, still the same checked voltages at the bulb holders, ok checked the bulbs, ok changed over the stalk, still the same problem ( unless the other stalk i have also is faulty, which is unlikely) Now, I did buy a replacement stalk from an earlier revision mr2, still the same problem. I even stripped down the indicator stalk and fitted it to my whole unit and the same problem also. Unless the stalk was also faulty which I do not believe it is, there must be another problem. Would a bad earth do this do you think? heres the wiring diagram, its for the US model but I suspect its the same. unless someone has a JDM wiring diagram for the headlights? 1991 MR2 BGB Online - Electrical

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11-16-2009, 04:01 PM	#2 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,692 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	Did the problem arise out of no where (i.e. one day they are working properly and the next, they are not)? or what? Need more details of when or how the problem started...

11-16-2009, 05:03 PM	#3 (permalink)
jdbecks No Skills Join Date: Aug 2008 Location: England Posts: 33 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	hi mate, yeah..one evening I got in my car, turned my headlights on and there was nothing. both at exactly the same time, there was no rain or anything either.

11-16-2009, 07:23 PM	#4 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,692 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	Ok, so let me get this straight, if you turn on the headlights, you do not get dipped beams with the switch in the dipped beam position but if you flip the switch to Full beams, you do get full beams?

11-17-2009, 02:56 AM	#5 (permalink)
jdbecks No Skills Join Date: Aug 2008 Location: England Posts: 33 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	if I turn my switch to the dipped postion I do not get dipped head lights, I get full beams and the full beam indicator light inluminates on the dash, My flash deos not work either, so if I pull the stalk to me to flash, nothing happens..although the lights do pop up, but the lights are not on.

11-17-2009, 02:54 PM	#6 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,692 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	Im guessing that if you push the switch away (normal activation for full beams) you get nothing? This really makes no sense... Is there anything that was done in the past that you know of that the headlight wiring (be it dipped beam or full beam) was tapped into or altered like fog lights or driving lights that are wired to activate with a particular beam???

11-17-2009, 03:52 PM	#7 (permalink)
jdbecks No Skills Join Date: Aug 2008 Location: England Posts: 33 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	cancel my last, the flasher and full beam deos work. Im just getting full beam lights on when my switch is selected for dipped, with the indicator light on the dash for full beams coming on.

11-17-2009, 04:24 PM	#8 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,692 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	Ok... so you get full beams with the switch in the dipped beam position, but what happens when you have the switch in full beam position??? No lights at all or still full beams???

11-17-2009, 06:59 PM	#9 (permalink)
jdbecks No Skills Join Date: Aug 2008 Location: England Posts: 33 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	when its at full beam postion, i still have full beams

11-17-2009, 07:35 PM	#10 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,692 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	Chances are that you have a short in the wiring being that you've tried differnt switches.... If it were me, I would unplug the harness plug and check both side just to make sure... Assuming that the wiring is the same for ya'll as it is for the US spec cars, unplug the black 14pin connector that connects the combination switch harness to the dash harness. Starting with the switch harness side, turn the headlight switch fully on and the beam selector to dip beam position. Make sure that you have continuity between Pin 3 and pin 9 and no continuity between pin12 and pin 9. After that you can flip the switch to the full beam position and you should have continuity between pin12 and pin9 and no continuity between pin 3 and pin 9 summery, headlight switch fully on. dip beam position = continuity between pin 3 and 9 only full beam position = continuity between pin 12 and 9 only. If you have continuity in on both at the same time then the switch is shorted. Now for the dash harness side, jump the headlight relay so you will supply power to the lights without the switchs being hooked up. if you short pin 3 to ground, you should have dip beams on only and if you short pin 12 to ground, you should have only full beams on. If you get full beams with either pin shorted, then the two wires are short together somewhere in the harness most likely... On other thing you can try as I have seen this happen once. Try un hooking one of the headlights and see if the other starts working normally. If it doesnt, then try hooking that one back up and un hooking the other and see if it starts working normal.... I say this cause I have once seen this exact problem and the short was actually in the filaments of the bulb. One filament broke and shorted to the other those cause both beams to become alive any time the headlights were on... hope all this helps...

11-18-2009, 10:50 AM	#11 (permalink)
jdbecks No Skills Join Date: Aug 2008 Location: England Posts: 33 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	Hi mate, Ive not been able to test this just yet, however, I would just like to add, when I use the flasher, the lights do not illuminate but the dash light deos come on ( pulling the stalk to the driver, to flash main beams)

11-18-2009, 12:20 PM	#13 (permalink)
jdbecks No Skills Join Date: Aug 2008 Location: England Posts: 33 Thanks: 0 Thanked 0 Times in 0 Posts iTrader Rating: (0/0% )	my apologies, I tested them tonight and they don't work.

11-18-2009, 03:45 PM	#14 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,692 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	Ok, to summerize the whole thing, dimmer switch in either dip or full position gives you full beams with the indicator light on too. Flash position give no lights at all but does illuminate the indicator light? This still leaves us with a short somewhere. Now why you dont get any light at all when in the flash position but you do get indicator really screws this up... It makes no sense unless right hand drive cars are wired differently.... I really dont see this being the case though.... I guess still the only way to tell whats up is to test the individual parts like listed above...

11-18-2009, 04:10 PM	#16 (permalink)
CJMR2T Fabricator Join Date: Oct 2009 Location: Lakeland, FL Posts: 3,692 Thanks: 3 Thanked 356 Times in 337 Posts iTrader Rating: (4/100% )	The biggest thing that is really confusing me with the way toyota wired the system is that according to the riding diagram, the full beam indicator is pulling from the dipped beams... The only thing that I can think of is that the its a circuit based on current flow resistance (i.e. when in dipped position, the path of least resistance to ground is through the switch so indicator will not light. When switch is in full beam position, there is still currrent flowing through the low beam side but the only flow path to ground is through the indicator light thus lighting it. This current must be very low to not light the dipped beams)... Seems kinda like a rather odd way to wire it unless there is something that Im missing..... When the headlamp relay is on, both the dip and full beam circuits are hot but the switch determines which circuit is open and which is closed to ground. A short between the two circuits would allow both to be closed when the switch is in either position (full or dipped)..... Now why in flash position, neither are closed doesn't make sense.... Im beginning to think that it is in the switch itself and its a combination of two problems a short and a broken / perminittly opened circuit. The only problem with my theory is that its hard to believe that two different switches have the identical same two faults.....