Jaims Posted January 27, 2014 Report Share Posted January 27, 2014 So thanks to some help from wayno I got my tilt column to work in my 1980 720 4x4. My break lights will not work. I did not change any wirering on the column. My fuses are good. So question, what could it be or where would you start? Yes I checked the bulbs. Also is there a good after market site for performance or oem parts. Quote Link to comment
DanielC Posted January 27, 2014 Report Share Posted January 27, 2014 Datsun 521 trucks have one of the simplest brake light circuits on any vehicle. There is no interaction between brake lights, turn signals, or any other lights. The brake switch light gets power from the fuse box, all the time. The wire at the beake light switch that does not have power all the time, goes to the brake lights. There are two locations for the brake light switch. On the brake pedal, in the cab, or on a pressure switch, in the engine compartment, where the junction block is for the front, and rear brake lines. It is common for the brake lights to lose ground. The taillight harness is grounded to the metal taillight frame, and that is grounded to the bed, and the bed in turn is grounded to the frame, and the frame should be grounded to the battery minus. You can usually fix a bad taillight ground by running a wire directly from the taillight frame, to the chassis frame of the truck. Here is a full wiring diagram. Here is a partial wiring diagram, just lights. The second diagram does not show the brake lights. The wires on the brake light switch are green, witha yellow stripe. If you suspect a bad switch, jumping the two wires at the switch should make the lights come on. Before you tear in to everything, check the fuses. Do not assume a fuse that looks good, is good. Check for power on both sides of the fuse, with the brake lights on. Then check both bulbs. Make sure the bulbs work. This was originally posted in the 521 section, and then moved here. the basic princeples will apply, not the details. Quote Link to comment
wayno Posted January 27, 2014 Report Share Posted January 27, 2014 You have had that area in your 720 apart for the tilt column conversion, did you unplug any of the wires going to the brake light switch, there are two sets of wires down there, one set goes to the clutch pedal switch, so I am wondering if you got them mixed up? There are two wires, both mine are yellow/red line. You must understand that the photos I am posting are of a 1980 wiring harness in a 1966 Datsun 520, so things are going to look different than a 720. Quote Link to comment
wayno Posted January 27, 2014 Report Share Posted January 27, 2014 Datsun 521 trucks have one of the simplest brake light circuits on any vehicle. There is no interaction between brake lights, turn signals, or any other lights. The brake switch light gets power from the fuse box, all the time. The wire at the beake light switch that does not have power all the time, goes to the brake lights. There are two locations for the brake light switch. On the brake pedal, in the cab, or on a pressure switch, in the engine compartment, where the junction block is for the front, and rear brake lines. It is common for the brake lights to lose ground. The taillight harness is grounded to the metal taillight frame, and that is grounded to the bed, and the bed in turn is grounded to the frame, and the frame should be grounded to the battery minus. You can usually fix a bad taillight ground by running a wire directly from the taillight frame, to the chassis frame of the truck. Here is a full wiring diagram. Here is a partial wiring diagram, just lights. Daniel, I am not sure why this is in the 521 section, as I believe that he is talking about his 720, I could be wrong though, but I see no 521 in his list of vehicles. Quote Link to comment
Jaims Posted January 27, 2014 Author Report Share Posted January 27, 2014 I hate my phone yes I ment to click the 720 section. Thanks n e ways. Yeah I'll check that when I get home wayno I think your right. My wires are the same color. My buddy looked at a diagrame and said those were the neutral safty wires. Quote Link to comment
datsunaholic Posted January 27, 2014 Report Share Posted January 27, 2014 1980 720s are the same way as a 521 - brake lights don't go through the column. Just from the pedal switch to the back. However, starting in 1985 they DID combine the stop/turn. So if that's where the tilt column came from, could cause all sorts of wiring issues. Need to use the earlier siglan switches. Quote Link to comment
Jaims Posted January 27, 2014 Author Report Share Posted January 27, 2014 I was able to use the old turn signals etc on the new column. Everytging works except brakes and hazzards. I'll check both places though. Quote Link to comment
datsunaholic Posted January 27, 2014 Report Share Posted January 27, 2014 Brakes an hazards don't share wiring, but they do share a fuse... Quote Link to comment
datson4life Posted January 28, 2014 Report Share Posted January 28, 2014 When i hit my brakes my left turning signals turn on, turn out i melted the wires by exhaust, cause the exhaust blew open Quote Link to comment
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