1970 521 truck Posted July 11, 2012 Report Share Posted July 11, 2012 Ok I have checked the switch its good what relay controls the brake lights and way to by pass it to make them work again Quote Link to comment
datsunaholic Posted July 11, 2012 Report Share Posted July 11, 2012 There is no relay. Just the switch. You have power to both sides of the switch when the pedal is pushed? Check the wiring to the rear. Quote Link to comment
DanielC Posted July 11, 2012 Report Share Posted July 11, 2012 Brake lights on a 521 are as simple as you can get. There is always power to the brake light switch, if the fuse is good. The switch is either a pressure switch in the engine compartment, on the cowl, or a switch on the pedal bracket. There is no interlock with the turn signals, or four way flashers. Just one switch that turn on two lights. Do you have power at one wire going to the switch? If so, jump the two wires at the switch. Do the brake lights come on? If not check the brake light bulbs. If the bulbs are good, a very common problem is a bad grounds. On a 521 that is new, the brake lights, and in fact all the lights in the taillight assembly ground to the bed of the truck. The bed in turn is grounded to the frame of the truck. The frame of the truck is in turn grounded to the engine block, and that is where the negative battery connection is made, completing the circuit. Quote Link to comment
1970 521 truck Posted July 13, 2012 Author Report Share Posted July 13, 2012 Ok found the Dang problem its with the fuse block. The truck sat for 6 years in the desert in covered time to clean that thing up all good now thanks Quote Link to comment
1lo620 Posted July 14, 2012 Report Share Posted July 14, 2012 Ok I was just going to post up a ? abpout brake lights for a 620.but I saw this so I am hi jacking this post... I had brake lights and now I dont, all other lights work...thought it was the switch, so I replaced it, but that wasnt the issue. I dont have 4 way flashers either, and yes I checked the fuses. so I guess it is in the rear lights themselfs? How do I check that...sorry I am not the best mechanic out there, and for sure not with wiring? Any help or suggestions would be greatful thanks.... Quote Link to comment
MikeRL411 Posted July 14, 2012 Report Share Posted July 14, 2012 Ok I was just going to post up a ? abpout brake lights for a 620.but I saw this so I am hi jacking this post... I had brake lights and now I dont, all other lights work...thought it was the switch, so I replaced it, but that wasnt the issue. I dont have 4 way flashers either, and yes I checked the fuses. so I guess it is in the rear lights themselfs? How do I check that...sorry I am not the best mechanic out there, and for sure not with wiring? Any help or suggestions would be greatful thanks.... The cheapest way to check is to buy 2 new bulbs. If it works, problem solved. 2 bulbs do fail at the same time or relatively close to the same time. Quote Link to comment
1lo620 Posted July 14, 2012 Report Share Posted July 14, 2012 The cheapest way to check is to buy 2 new bulbs. If it works, problem solved. 2 bulbs do fail at the same time or relatively close to the same time. Ya that was going to be my next thing to do...we will see what that does and go from there I guess...... Quote Link to comment
banzai510(hainz) Posted July 14, 2012 Report Share Posted July 14, 2012 I assume you have 12volts at one side of the switch. Then if you press the switch with will pass thru to the other side. Then switch at least works. to towards the rear Now if you DONT have 12volts at one of the ends of the swtich(under thepedal) I would ck foward towards the fuse box. Sometimes reconnecting the connector at fuse box will clean the corrossion off. Replace the fuse even if it looks good. On 510s the wireunder the fuse bock will corrode till it breaks off. on 510s the horn is on the brake fuse. See if that brake light in a digram share another circut and try it out then you know for sure its the same circut and fuse box related Quote Link to comment
ggzilla Posted July 14, 2012 Report Share Posted July 14, 2012 The wrong way to fix this is start buying parts. Instead, find out which part is bad and clean it or if necessary replace it. Quote Link to comment
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