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620 brake lights


darrel

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'79 620 kc.

 

The brake lights work on the left but not on the passenger side.

 

Parking lights, turn signals and hazards all work both sides, as well as the front turn signals and parking lights.

 

Using a multimeter, I am getting power to the harness connector in the back on the passenger side, brake, taillight, etc.

 

I have read someone had a problem with their combo switch(turn signal switch). They only had one side brake light.

 

http://community.ratsun.net/topic/5708-no-more-brake-lights/page__hl__%2B620+%2Bbrake+%2Blights__fromsearch__1

 

Electrical gremlins go across the boards on these older cars and trucks. The 240z even have problems and only working the turn signal switch will help. I guess I will try that first.

 

 

I will replace all bulbs so hopefully it might be a bad bulb even though they all look good and light up, except for the brake lights on passenger side.

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OK the brake and the turn signal shares the same wire, so there is a left and a right brake signal wire. If the signal works on the rear pass side then the wiring from the turn signal switch back including the lamps has to be alright.

 

Now the turn signal...

When the turn signal is in the OFF position power from the brake peddle is fed equally to both the left and right rear signal wires: Light Green/Black stripe wire for the right and Light Green/Red wire to the left. When the turn signal arm is moved it disconnects the brake signal to that side wire, and connects the flasher unit to it instead. The other side is unaffected.

 

So... there is flasher operation on the rear right but no brake. I would remove the steering wheel and the two piece clam shell around the steering column to get at the turn signal properly. Inside you should see a Green/Yellow wire (this is the brake signal from the peddle) it should be connected to both the Light Green/Red wire and also the Light Green/Black wire. If you look carefully you may see that the wire has become un-soldered and there is no connection to the Light Green/Black wire.

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  • 3 months later...

The Turn Signal switch on a 620 has zero to do with one brake light working but not the other. In some cars it does, but not with a Datsun 620. Instead, look at the combo lamp, it may have a bad ground, or a dirty connection in the lamp socket. Or even worn contact on the bulb. You already confirmed it is getting voltage back, so don't mess with the T/S switch.

 

Datsun electrics are very good and reliable, but now that they are 30 years old sometime problems occur -- mostly due to slight corrosion.

 

Using a multimeter, I am getting power to the harness connector in the back on the passenger side, brake, taillight, etc.
Very good. Now check that is also has a good ground. Remove the bulb and look for very light corrosion.
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i respectfully disagree. i just took mine apart. the brake lights run through the turn signal switch,

 

6ee9f132.jpgwhich you can trace all the way back to the plug for the light housings. its the light green /red and light green black wires

 

dcea74e7.jpg

you can see the two 90* metal contacts that touch the copper blade, one of mine was a little worn, so i bent it back in a little bit and my brake light problem was solved

 

d22ebfda.jpg

here you can see the 3 contacts the shoe rides against to complete the circuit. mine was also dirty and corroded.

 

6f6b7814.jpg

heres a picture of the little shoe that rides on the contacts.

 

65962cd3.jpg

heres the parts of the shoe. WARNING!!! when you start taking the phenolic plate with the contacts off, this shoe will want to jump right out and scatter all its little small parts on your floor.

 

but, like i said, i had the exact same problem. i got very very low voltage at the light assembly and figured i had a short or bad ground, and traced it as far as where the wires split under the steering column and was stumped. i wish i would have read this thread first, i coulda saved two days of ripping my truck apart... cause it no shit took me 5 minutes to fix.

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Yeah brake lights just go right through the turn signal switch (if off) but when selecting the switch disconnects the brake signal to that side and connects the flasher unit. It's interesting how this was done to allow the brake and the turn signal to use the same bulb but not interfere with each other.

 

On mine I found one of the wires with a blob of solder had come off. A touch with a soldering iron and still working....

 

6ee9f132.jpg

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With mine, I was indicating very low amounts of power all throughout the circuit when the circuit was energized. I started at the tail lights and worked my way forward tearing apart the harness looking for the short. Major PITA.

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  • 5 months later...

I must have looked cockeyed at my multi meter. I took more time and I wasn't getting any power from the turn signal switch back. I picked up a switch at the salvage yard a couple of weeks ago and replaced it. It is working fine now, but the lever is loose and the cancel isn't working on the right side, but all the lights are.

 

Using my factory service manual(BE-12), tonight I checked into the old switch. Now before I found another switch I looked over the old switch a couple of months ago and all solder points were tight and solid. So I cleaned and greased the turn signal portion of the contacts. No change. Now when I checked it tonight, the solder joint at the Ltg/B wire was disconnected/off at the signal portion of the switch.

 

Following procedure in the manual for continuity it should work as advertised once I resolder the connection.

 

Now I will solder, clean and grease the whole switch and put it back in since that seems to be the problem.

 

 

Thanks again all for the input. Now to find the ever elusive tach for the '79 before I swap the virtually uncracked dash and LED lights.

 

I did take the switch apart and know about the little things that can go flying around. I'm surprised the wired did't come completely loose then. It must have been on snug enough but not come off even with the twisting and turning I was doing to it.

 

Sorry it took me so long to report back, but I really haven't been doing to much with the truck, except replace the head gasket, etc. I always like to get extra parts in case of a worse case scenario, after all our vehicles are getting older. ;-)

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  • 4 weeks later...

Is this similar to the way a 720 is wired up?  I did a search and came to this. 

 

My 86's running tail lights stay on even when everything is turned off and the key is removed.  In addition, these lights go out when I take out the brake light fuse.  Any ideas??

 

Thanks,

Dave in NC

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Is this similar to the way a 720 is wired up?  I did a search and came to this. 

 

My 86's running tail lights stay on even when everything is turned off and the key is removed.  In addition, these lights go out when I take out the brake light fuse.  Any ideas??

 

Thanks,

Dave in NC

 

Yes, but you have a different problem.  Well, unless your brake lights don't work properly. 

 

The running lights are probably on the same fuse as the brake lights, as they're on a "BAT" fuse, not powered in any way by the ignition switch.  Brake lights and Head/Tail lights work even without the key.  So what has likely happened is the running light relay, which might be in the switch unit itself, is stuck, or the switch is bad.  Either way, I think you ned to replace the entire combination switch unit (which requires removing the steering wheel and column cover). 

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Are the 720 brake light switch set up the same way the zx switch is set up? If so, check the brake pedal where the brake light switch is. Is there a hole in the pedal where a plastic plug may have been? And maybe you vacuumed up some parts that were on the floor board when this first started?

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Yes, but you have a different problem.  Well, unless your brake lights don't work properly. 

 

The running lights are probably on the same fuse as the brake lights, as they're on a "BAT" fuse, not powered in any way by the ignition switch.  Brake lights and Head/Tail lights work even without the key.  So what has likely happened is the running light relay, which might be in the switch unit itself, is stuck, or the switch is bad.  Either way, I think you ned to replace the entire combination switch unit (which requires removing the steering wheel and column cover). 

Thanks, I'll check the relay. Took off the steering column switch assembly, carefully cleaned, regreased with dielectric grease where needed and appropriate, checked operation with multmeter and put back on.  Same problem.

 

By the way, is there any place that one can get a diagram of the wiring for these trucks that is readable without being fluent in hieroglyphics??  Maybe something that overlays the wiring over a diagram of the truck??

 

Thanks,

Dave in NC

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  • 1 year later...

wow i spent 2 nights trying to figure out my brake light problem for the right side. I was stumped even after taking apart the rear harness. I decide to search on ratsun and BOOM! found my problem on the first search result. I just needed to bend the tab more and sand the contact a bit and all was fixed. THANKS Ratsun!

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  • 1 month later...

please help me.  My turn signals/ blinker burned from a wire shortage. I can't seem to find another replacement anywhere. The ones I do find don't match up with my pins. Any ideas. I was thinking of rigging a universal signal up but still the wires don't match my 1979 620 pick up

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  • 2 weeks later...

I have a somewhat similar problem. all my bulbs are good and only my right blinker wont work.the bulb was somewhat corroded and i dont have a multimeter.is this a problem related to the seitch or do i need to start looking somewhere else?all of my connections in the harness under the steering wheel look good and feel snug? Any guiding help is appreciated and someone help the guy above!! Lol thanks!

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Don't need a multi meter. Get a $3 test lamp. Its an alligator clip on the end of a wire with a 12 volt bulb and a pointy probe on the other. Clip to a ground and the lamp lights when the probe touches a live wire. Clip to 12 volts and it lights when touching any ground.
 

 

testlight.gif

 

 

On the 620, the turn signal and the brake lights share the same bulb so check that the brake lights all work. If the brake lights work on both sides then the bulb and the wiring are not the problem. Do they?

 

 

If corroded, clean the receptacle part and make sure the contacts in the bottom are spring loaded and free to move. Replace the bulb.

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ok when i tested the harness with a ground and hot tester i got a ground on all pins except for the green and yellow wire pin which was only a ground on the male part of the connector does that make sense? ive had similar problems on other vehicles but its usually been fuses or ground problems i dont have a clue of what this is 

 

 

https://farm4.staticflickr.com/3843/14751580211_d86d195422_m.jpg

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On the rear lights all are using the same ground so if on works the ground is good.

 

I had one bulb bad which i had replaced before posting my lights blink like normal when my hazards are on its only when i put my right side blinker on that it just stays lit up and doesnt blink the left side and all brake lights function properly

 

If both the brakes lights and the 4 ways work, then the wiring and bulbs at the back are good.

 

The turn signal on the 620 when used, first disconnects the rear lamp from the brake light signal and then connects the turn flasher. Otherwise the brake signal would interfere and both sides would flash. When the signal lever is returned, the brake light is re connected.

 

I had a turn signal problem. I took the steering wheel off to get at the turn signal and found a wire had come off at the solder joint. A few seconds with a soldering iron and all was good. Once the wheel is off you can watch the contacts being opened and closed as you work the lever.

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  • 4 years later...
On 7/1/2012 at 3:23 PM, datzenmike said:

Yeah brake lights just go right through the turn signal switch (if off) but when selecting the switch disconnects the brake signal to that side and connects the flasher unit. It's interesting how this was done to allow the brake and the turn signal to use the same bulb but not interfere with each other.

 

On mine I found one of the wires with a blob of solder had come off. A touch with a soldering iron and still working....

 

6ee9f132.jpg

 

Thanks mike! I know this post is old but it helped me solve my no driver side brake light issue. Mine wasn’t a bad solder connection, it was the copper bridge on the inside. One of the leads wasn’t making a good contact. A little sanding and bending and bam! Both brake lights work! 

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