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'76 Chinook / Hilux low beams trouble


Logan

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Hey guys!

I recently Picked up a 1976 Chinook that i will make a post about shortly, but im trying to troubleshoot this little electrical problem that has me stumped.

Heres what happens:

Pull knob for lights - dash lights up, all running lights come on.. but no low beams...

Pull knob further for highbeams - high beams come on in full, high beam indicator lights up.

As far as i can see there is NO fuse for the headlights on this model? i can take out every fuse in the fuse box (none of which are labeled for headlights)  and the high beams still come on...

I tested the Relay with a brand new replacement (which was not easy to come by) and had the exact same results.

multimeter tested the female leads that connect to the sealed beam headlight, and got no reading from the low beam connector with knob at low... so theres clearly no power going to the lamps when set to low beams...

now before i go and tear out all the wiring i was wondering if anybody might have any ideas or something else i can try to pinpoint the problem.

thanks! appreciate any advice!

 

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6 hours ago, Logan said:

Hey guys!

I recently Picked up a 1976 chinook that i will make a post about shortly, but im trying to troubleshoot this little electrical problem that has me stumped.

Heres what happens:

Pull knob for lights - dash lights up, all running lights come on.. but no low beams...

Pull knob further for highbeams - high beams come on in full, high beam indicator lights up.

As far as i can see there is NO fuse for the headlights on this model?

 

Relay only has one set of contacts that are used for low-beams and high-beams.   Same relay has only one power feed via a fusible link that also powers low-beams and high-beams. If you have NO low-beams but the high-beams work fine - the issue has to be in the dimmer-switch circuit, assuming the low-beam bulbs are not burned out. I can post a complete wiring diagram if wanted.

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Check the bulbs first. It's fairly common for one lamp to be out for awhile before some one fixes any of them.

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I had the same problem years ago on a Corvair. The problem ended up being oxidised contacts where the wiring harness plugged in to pass through the fire-wall. After sanding all the contacts the problem was solved. That said, I would check the bulbs first.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

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thanks for the input!

 I would love a wiring diagram if possible JD that would be awesome..

going to go test the sealed beam light right now just to be sure,  does anyone know if the headlights in these older hilux models had a fuse somewhere?  because i cant seem one.

how would one go about testing the dimmer switch circuit?

 

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Like I already stated - no fuse that is specific to just a high beam or low beam.  There IS a fusible link that is the power feed for all the head-lights at the relay.  Here is the 1977-78 diagram. I have the 76 and 77 diagrams at my other place and I won't be there for a few days.  Pretty much the same as I recall though.

complete_best.jpg

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10 minutes ago, jdemaris said:

A closer view.

heallitesclose.jpg

thank you! !

I'm not very electrically literate so excuse my possibly obvious questions, but this schematic will definitely help.

quick questions:  

A) does "fuseable link" mean someone could have put in a fuse if they wanted to? but probably haven't in my case?

B ) is the dimmer switch located at the control knob? is it part of that whole piece behind the knob? or is it somewhere between the control switch and the lights?

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1 minute ago, Logan said:

thank you! !

I'm not very electrically literate so excuse my possibly obvious questions, but this schematic will definitely help.

quick questions:  

A) does "fuseable link" mean someone could have put in a fuse if they wanted to? but probably haven't in my case?

B ) is the dimmer switch located at the control knob? is it part of that whole piece behind the knob? or is it somewhere between the control switch and the lights?

If the fusible link was blown - none of the headlights would work - so you can rule that out.  It is just a piece of wire with special insulation so the wire inside can melt without the outside insulation melting.  And yes, it could be cut out and replaced with a circuit breaker or fuse (not your problem though). 

Dimmer switch is on or in the steering column as I recall. 

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In systems troubleshooting, I have always liked dividing things up.  In this case I would check the fuses first then pull one of the bulbs out and use a simple and cheap test light on the plug.  That would be testing the  both ends of the system.  Voltage at the headlight relay would also be a good point to test.  Should get 12 volts there as well.  I'd be pretty surprised if you didn't find the problem with just these three points but at least you'd know which end to start at (light or control end).

There is an open question regarding the bulb itself.  Are you sure it is not the bulb?  How about the plug itself as suggested above.  Have you taken one of the bulbs out and had a look? These get dim over time so it wouldn't be a waste to pick up a couple new bulbs anyway.  I changed mine before I put it on the road.

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Mine here seems to work on a knob system

pulling it one notch turns on dash, running lights and low beams (if they worked), turning it clockwise dims the dashboard lights, and second notch is high beams and indicator light

is the dimmer switch whats behind the knob in the photos there?

image3.JPG

image2.JPG

image1.JPG

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Logan, you are good at asking questions but not so good at answering them.  Can't help without answers to the various questions that have been left open above.  Also, ignorant or not, you are going to need something to test with.  A cheap test light from an auto store would go a long way in help you figure this out.

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14 minutes ago, Back East Don said:

Logan, you are good at asking questions but not so good at answering them.  Can't help without answers to the various questions that have been left open above.  Also, ignorant or not, you are going to need something to test with.  A cheap test light from an auto store would go a long way in help you figure this out.

hahah I know :-) Thanks for helping me trouble shoot! i appreciate it..

I tested the sealed beam bulbs with direct current and they work fine..

i get no voltage at the female low beam plug wire at the light when set to low beams.. get 12volts at the high beam wires when set to high beams..

so there is no power going to the lights when switched on to low beam..

tested at the relay and get 12 volts at the Red-blue wire when set to LOW, also get 12V at the RED-blue wire when set to HIGH, get no reading from the solid red when set to either low or high beam.

is there a test i can do with a test light that i can't do with a multi meter?

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38 minutes ago, Logan said:

Mine here seems to work on a knob system

pulling it one notch turns on dash, running lights and low beams (if they worked), turning it clockwise dims the dashboard lights, and second notch is high beams and indicator light.

I don't have one of your vintage, but I'd expect the first notch to be panel and running lights, second notch adding headlights with a separate dimmer switch. Is Toyota different?

At least from your pictures, it doesn't look like your wiring has been butchered, as so often happens.

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22 minutes ago, Logan said:

I tested the sealed beam bulbs with direct current and they work fine..

i get no voltage at the female low beam plug wire at the light when set to low beams.. get 12volts at the high beam wires when set to high beams..

so there is no power going to the lights when switched on to low beam..

tested at the relay and get 12 volts at the Red-blue wire when set to LOW, also get 12V at the RED-blue wire when set to HIGH, get no reading from the solid red when set to either low or high beam.

is there a test i can do with a test light that i can't do with a multi meter?

Ok, so bulb is good.  One end down.  High beams work would indicate the relay is good and source from fusible link is not the problem.  If the connectors to the headlamp look good things point to the dimmer switch for high/low beam.  If you have a meter and know how to use it, you are good.  Test light = dummy light.

 

1 hour ago, Logan said:

pulling it one notch turns on dash, running lights and low beams (if they worked), turning it clockwise dims the dashboard lights, and second notch is high beams and indicator light

This one baffles me.  Pulling it one notch should only turn on the running lights.  Second notch turns on the headlights by energizing the relay.  If the high beams are on in that position then there should be another switch to turn on low beams.  My old 67 plymouth had a button you stomped on with your foot on the floor.  Most modern cars are switched with an arm on the steering column.  What is on the column?  Does the one of the arms move forward and back to switch between high and low?   The diagram on the lower left corner shows a dimmer switch.  If it were connected to the light control switch, there would typically be a dashed lined or note connecting them as one unit.  My thinking is you have the operation of the switch wrong in the statement above.

 

1 hour ago, Logan said:

is the dimmer switch whats behind the knob in the photos there?

This is the dimmer on the light switch itself for the dash panel lights.  Jagged line with an arrow going through it on the light control switch.

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24 minutes ago, Derek up North said:

I don't have one of your vintage, but I'd expect the first notch to be panel and running lights, second notch adding headlights with a separate dimmer switch. Is Toyota different?

At least from your pictures, it doesn't look like your wiring has been butchered, as so often happens.

so this might be one of the most obvious dummy moments of my life but....

you were right on the money. I hadn't even considered it because when i first drove the Chinook in the dark i pulled the knob labeled "LIGHTS" and nothing happened - pulled it again and the high beams came on.. i was like WHERE ARE THE LOWS??... immediately thought they must be the first notch of the knob and weren't working.

I didn't even try pulling or pushing the windshield wiper stick cause it looked so basic, and this whole time ive been  chasing an electrical problem that doesn't exist!!!

apologize to everyone for being an idiot!

but extremely grateful for all the help and advice!

I'm sure I'll be on here a lot now that i have this old rig...will try to be a little more thorough before questioning everyone next time i promise.

cheers :-)

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6 minutes ago, Logan said:

so this might be one of the most obvious dummy moments of my life but..

If you are young you have plenty of time to top this.  If you are older, you'll likely top it anyway.  Life has plenty of these moments.

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8 hours ago, jdemaris said:

So ; . if I understand you correctly, you hit the dimmer-switch control and both the low-beams and high-beams worked . . correct?

yup...  never had a truck with that "lights" knob before. when i saw it i didn't even think to try the usual forward - back switch on the signal lever for some reason. 

was immediately hypnotized into thinking there was an electrical issue. was super weird.

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To answer your question about a fuse for the headlites, NO, most vehicles have a breaker built into the headlite switch that will make & break rapidly if you have a short somewhere in the circuit..  This will keep the lites flashing off & on until you can get off the hiway.. Imagine if there were a fuse & it blew at 60 MPH on a dark night..

The built in breaker will SAVE YOUR BUTT............  I'm not sure about your application, buy all cars that I have knowledge of work this way...............donnie

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a breaker on the headlights is something I have not seen on a Toyota or a datson. yes on American cars . my 74 DATSEN b210 had one fuse for both headlights not a good safe set up . old time V W and Toyotas 2 fuses right and left on 2 different circuits. then you still have one side.i will check in my older books on Toyotas. JD is correct the fuse link powers the headlights .  I had forgotten that and on some 70s Toyotas the second side of the link powers the heater blower .

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that switch in the picture is what was in my corona wagon 1977. but I had a 78 pickup and motor home  set up just like LOGANS.and every once in a while the turn singnals  on the ones like his will fail to operate. pumping the four way flasher knob on and off fixes that . seems some  thing gets cruded in the contacts.

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