76_620 Posted January 29, 2020 Report Share Posted January 29, 2020 I have a 72 521, both front and rear signals and hazards work, headlights work, High beams work, brakes work, rear running lights do not work ??? Any suggestions ? Quote Link to comment
Draker Posted January 29, 2020 Report Share Posted January 29, 2020 Are they hooked up? Are the bulbs good? Quote Link to comment
datzenmike Posted January 29, 2020 Report Share Posted January 29, 2020 When you pull the headlight switch out to the first position do the front facing amber parking lights working? What about the side amber and red clearance lights? the license plate lamp? These are all on that circuit. Lastly do the dash lights come on? If no to all these then check the fuses under the hood. Have someone watch while you touch a quarter (briefly!) across the contacts. I don't know which one it is so you'll have to do all of them. When the lights come, on, that the problem fuse, clean the fuse holder contacts and replace the fuse. Quote Link to comment
DanielC Posted January 29, 2020 Report Share Posted January 29, 2020 Check fuses, glass tube fuses can look good, but still be bad. Turn the lights on. Then check for voltage on the cab side of all the fuses, with a test light. I think the tail light fuse is one of the two fuses in the middle of the six fuse box. Quote Link to comment
banzai510(hainz) Posted January 29, 2020 Report Share Posted January 29, 2020 (edited) usually the fuse and I think the Horn will not work Maybe this is 510 but the dash light might be out also is a big clue. its the FUSE first or dirty connection on fuse. Or is it brakes lights ? ck fuse. 95% im sure that it Edited January 29, 2020 by banzai510(hainz) Quote Link to comment
76_620 Posted February 1, 2020 Author Report Share Posted February 1, 2020 On 1/29/2020 at 5:55 AM, datzenmike said: When you pull the headlight switch out to the first position do the front facing amber parking lights working? What about the side amber and red clearance lights? the license plate lamp? These are all on that circuit. Lastly do the dash lights come on? If no to all these then check the fuses under the hood. Have someone watch while you touch a quarter (briefly!) across the contacts. I don't know which one it is so you'll have to do all of them. When the lights come, on, that the problem fuse, clean the fuse holder contacts and replace the fuse. When I pull the switch on the first position the front facing lights don’t work, when I pull it on the second they don’t work either, they only work when theKey switch on the truck is on and on the second position on the light switch. Dash lights all work, liscence plate light doesn’t work. I tried the quarter trick no luck ? Wondering if I have a bad ground in the rear tailights ? Checked all fuses with test light all are good, I wil clean and soak fuse box in vinegar today we’ll see what happens. Quote Link to comment
datzenmike Posted February 1, 2020 Report Share Posted February 1, 2020 You only mention the fronts. Do the rear lights do the same or are they working normally? Quote Link to comment
76_620 Posted February 2, 2020 Author Report Share Posted February 2, 2020 1 hour ago, datzenmike said: You only mention the fronts. Do the rear lights do the same or are they working normally? The rear are not working Quote Link to comment
datzenmike Posted February 2, 2020 Report Share Posted February 2, 2020 So they only work with the ignition on??? Well the lighting is on the fuse box side that is powered at all times. Things like the horn, brake lights, 4 way flashers, interior lights and clock should all work without the ignition on. Quote Link to comment
banzai510(hainz) Posted February 3, 2020 Report Share Posted February 3, 2020 On 2/1/2020 at 5:13 PM, datzenmike said: So they only work with the ignition on??? Well the lighting is on the fuse box side that is powered at all times. Things like the horn, brake lights, 4 way flashers, interior lights and clock should all work without the ignition on. somebody do a hack job to bypass?????? lights should come on with no ignitions switched. Period. means the feed wire to the fuse box thru the fuse. Quote Link to comment
yenpit Posted February 14, 2020 Report Share Posted February 14, 2020 All of the above ^^^^^^, but there is also an OEM headlight RELAY that can go bad, yes? Man, if you are only getting the sidemarker lighting with key ON, something is really amiss! Soak the fuse box (if it is original????) in white vinegar for a day or two to clean it. If you can post pics, a pic of the top & bottom, clearly showing all of the terminals so we can help verify it is correct. That might help the headlights, but I'm not sure simply cleaning the fuse box will fix the sidemarkers, cuz like they said above..........ALL of the lighting should work WITHOUT the ignition on.............. Be aware that most of the wiring schematics in print & online are NOT correct for our USA spec 521's (same issue with our 510's!). The most common color coded schematic that I see the most online shows SIX wires at the headlight switch, pretty sure ours only had FOUR wires at the switch, my 1972 521 only has FOUR wires! Quote Link to comment
yenpit Posted February 14, 2020 Report Share Posted February 14, 2020 FYI I just bought the NEW NOS OEM "Niles" 521 headlight switch off eBay from Thailand, but it is a SIX wire switch.............I'm ASSUMING this switch matches the SIX wire schematic mentioned above, that I do not think is USA spec.......?? Again, my 72 521 only has FOUR wires coming out of the main harness for the headlights. This NEW six wire switch also has a "twist" position like the courtesy/overhead light on a later 70's-80's car ie Ford Chevy etc when they still had headlight "pull on" switches, but I heard (DanielC??) that the JDM trucks might have had fog or driving lights, which MIGHT explain the "twist" on position........?? FYI the "twist" does not work in the OFF position, it only twists in the first (sidemarker lights & tail lights) & second (sidemarker lights, tail lights & headlights) positions. Our tech just ran a continuity test for me on the NEW NOS six wire headlight switch & he does NOT think I can make this NEW six wire switch work by deleting the other TWO wires. Crap! 😝 At least this NEW NOS switch was cheap............... 🙄. Still on the hunt for a FOUR wire switch that will work............. Funny......I grew up with these "pull on" switches on cars. Our tech is much younger & has never had a car with a "pull" on switch..........only the rotary style headlight switches of later cars! (oddly the 70-83 Z ZX's all had a rotary headlight switch). I feel old!! Quote Link to comment
Zonargx Posted July 5, 2020 Report Share Posted July 5, 2020 On 1/28/2020 at 9:33 PM, 76_620 said: I have a 72 521, both front and rear signals and hazards work, headlights work, High beams work, brakes work, rear running lights do not work ??? Any suggestions ? I have a 1971 521 and I too was having the same problem as yours. I started to inspect under the truck and notice the truck had a towing connection hooked up and also didn’t have power so I traced it to about under the cab (passenger side of the chassis)where it was splices into the wire that supplies power to the rear runing lights as well as the LP lights and there was power before the splitting section and not after. I cut the wires removed the one that was for the towing connector as I’m not gonna tow in that truck and repaired the wire. I took of all the towing connection and wires off fixed all the spliced areas and that fixed it now I have rear running lights and LP lights. You might have something similar as me and just fixing the wire under the cab area (passenger side of the chassis) Remember the wire is red with a grey or light blue strip not sure as colors are a bit faded haha Quote Link to comment
datzenmike Posted July 5, 2020 Report Share Posted July 5, 2020 Had a '71... same thing. Random lights out. Previous owner has spliced in a trailer plug then someone cut it off and just wrapped it up with electrical tape. He might have done a better job. Three months of the year in Ontario are freezing, muddy, slush, salt, and sanded roads. When I unwrapped the harness the copper wires had corroded into blue copper sulfate mush. Quote Link to comment
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