darrel Posted March 26, 2012 Report Share Posted March 26, 2012 '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. Quote Link to comment
datzenmike Posted March 27, 2012 Report Share Posted March 27, 2012 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. 1 Quote Link to comment
darrel Posted March 27, 2012 Author Report Share Posted March 27, 2012 Thanks Mike. I am going to go digging into the turn signal switch next after getting the heater hoses and radiator sorted out. This will be a great help. Quote Link to comment
datzenmike Posted March 27, 2012 Report Share Posted March 27, 2012 Either a bad connection or, like my 620, the brake wire was loose where it was soldered on. I just hit it with a hot soldering iron and good to go. 1 Quote Link to comment
cdub42 Posted July 1, 2012 Report Share Posted July 1, 2012 OMG!! I've taken my entire truck apart chasing this EXACT gremlin! It's been frustrating as hell! I can't wait to finish dinner and run out to my garage to fix this. Quote Link to comment
ggzilla Posted July 1, 2012 Report Share Posted July 1, 2012 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. Quote Link to comment
cdub42 Posted July 1, 2012 Report Share Posted July 1, 2012 i respectfully disagree. i just took mine apart. the brake lights run through the turn signal switch, which you can trace all the way back to the plug for the light housings. its the light green /red and light green black wires 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 here you can see the 3 contacts the shoe rides against to complete the circuit. mine was also dirty and corroded. heres a picture of the little shoe that rides on the contacts. 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. 1 Quote Link to comment
cdub42 Posted July 1, 2012 Report Share Posted July 1, 2012 if just one of the contacts wasn't completing the circuit the brake light won't work but the turn signal will still work and it will still light up when the headlights are turned on. confusing as hell to wrap your mind around, even when i was staring at the wiring diagram http://www.davidcmur...dat620-1979.pdf Quote Link to comment
datzenmike Posted July 1, 2012 Report Share Posted July 1, 2012 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.... 1 Quote Link to comment
ggzilla Posted July 2, 2012 Report Share Posted July 2, 2012 Good to know. Thanks. In Darrel's case he measured power to the light, so the power wasn't stopping at the switch. Hopefully he'll see our posts and get it fixed. Quote Link to comment
cdub42 Posted July 2, 2012 Report Share Posted July 2, 2012 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. Quote Link to comment
darrel Posted December 4, 2012 Author Report Share Posted December 4, 2012 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. ;-) Quote Link to comment
ggzilla Posted December 4, 2012 Report Share Posted December 4, 2012 Good to hear. Just needs some tlc Quote Link to comment
Papasmithnc Posted January 1, 2013 Report Share Posted January 1, 2013 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 Quote Link to comment
datsunaholic Posted January 1, 2013 Report Share Posted January 1, 2013 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). Quote Link to comment
darrel Posted January 1, 2013 Author Report Share Posted January 1, 2013 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? Quote Link to comment
Papasmithnc Posted January 3, 2013 Report Share Posted January 3, 2013 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 Quote Link to comment
5t341tH Posted June 4, 2014 Report Share Posted June 4, 2014 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! 1 Quote Link to comment
leonardpiha Posted July 14, 2014 Report Share Posted July 14, 2014 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 Quote Link to comment
stormsinger54 Posted July 26, 2014 Report Share Posted July 26, 2014 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! Quote Link to comment
datzenmike Posted July 26, 2014 Report Share Posted July 26, 2014 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. 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. Quote Link to comment
stormsinger54 Posted July 27, 2014 Report Share Posted July 27, 2014 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 Quote Link to comment
stormsinger54 Posted July 27, 2014 Report Share Posted July 27, 2014 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 Quote Link to comment
datzenmike Posted July 27, 2014 Report Share Posted July 27, 2014 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. Quote Link to comment
bigboy620 Posted April 3, 2019 Report Share Posted April 3, 2019 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.... 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! 1 Quote Link to comment
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