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front hazards on when lights are turned on


family521

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Hi I have used Ratsun many times but now have a reason to do my first post. I am working on my families 1970 521 that my grandfather bought new from the dealer. The other day I finally got it going and then decided to check the lights. I had headlights that worked but nothing else. When it was parked two years ago in my dads garage all the lights were workign on it.  I took off the fuse box, soaked it in vinegar cleaned it and reinstalled it with new fuses. Now all the lights work but the front turn signals and the indicators on the dash are lit up when the headlights are turned on. When the lights are on you can't use the hazards or the turn signals. I know that all the wires that go to the fuse box are back in the same place since I took pictures before and when I compare them to the fuse box now every wire is plugged back in the same spot. Any ideas? Thanks JM

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Bulbs may be installed wrong. Take a look and you'll see that they actually only screw in in one position but... you can force them in 180 out. This would move the two contacts on the bottom and instead of the dimmer running light you would have the much brighter turn or four way lamps lit.

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Full wiring diagram:

521wires.jpg

 

Lights only diagram:

LightWires.jpg

 

The front park/turn signals ground to cab sheet metal. Check to make sure that ground is good.

 

Check some other grounds too.  The negative battery cable grounds to the cylinder head.  There should be a pigtail that goes down to the alternator frame also, grounding it.   There should be a second ground wire that goes from the alternator frame to one of the bolts that hold the voltage regulator to the fender.  Make sure the engine is grounded to the frame of the truck, make sure the bed is grounded to the engine, through the frame. 

 

It is important that the cab sheet metal stays grounded to the engine.  If this ground goes away, the cab sheet metal tries to ground through the throttle cable, and destroys it.

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The ground wire to the alternator case should be sized to the alternator output.  I would use at least a 10 gauge ground wire on a stock 35 amp alternator.

 

The turn signal housing has two #10-32 studs that hold it to the sheet metal.  The studs have nuts, put on from the back side.  There are mud covers inside the wheel opening, held to the sheet metal with tapping screws.  Remove the mud covers to get access to the nuts holding the turn/park light housing.   There are only two wires going to each turn/park light housing.

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Most of the time this problem is an incorrectly installed bulb (as Mike stated) or a incorrect single-contact bulb being used in a 2-contact socket.  The turn signal and brake bulbs are all of that type.  But a bad ground can cause it too, though the housing with the bad ground is usually easy to detect because that light will look different than the others.  And corrosion in the bulb sockets can do this too.

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Hey  sorry its taken me so long to reply guys but between work, coaching, jury duty, and a cold I haven't had time to work on the truck. I replaced both turn signal housings since both had a lot of corrosion and rust in the light bub sockets. The passenger side light also wasn't getting a good ground because that part of the body is bent from when my uncle was learning to drive back in 1970. I added in a pigtail ground to another place of the body and both of the lights are working correctly now. The only problem is that the turn signal indicator lights on the dash are still turned on when the running lights are turned on. If you turn the hazards or the turn signal on then the indicator lights flash on and off like they should. Any ideas? Also Daniel C as far as the ground that goes from the Alternator frame to the voltage regulator is there a stock wire or is that one that I need to add on? There is a stock wire that seems to be a ground that is held on by the left mounting bolt, is this a stock ground? 

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Alternator frame to voltage regulator is a stock wire.

 

The instrument cluster also needs a good ground.  Here is a pin out diagram of the socked on the instrument cluster.

Pinout.jpg

It is also possible that the ground wire to the instrument cluster is good, but somewhere between the ground pin on the circuit board and the turn signal lamp holders, the ground connection is lost.  Clean the copper traces where the lamp holder contacts make the connection to the board.

 

If you remove the instrument cluster from the dashboard, disconnect the negative battery cable first.

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So I cleaned all the contact points on the cluster and also on the bulb holders. The turn signal lights now are not on when the lights are turned on, but there is now no illuminating light on the right hand side of the cluster and also when the lights are on the right turn signal light will not light up, for either the turn signal or the hazards, the left works great all the time, and the right one works when the lights are not turned on. Any ideas about what now is up? 

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You can use the pinout diagram to bench test the instrument cluster.

Get a 12 volt battery, or hook two wires up to the truck's battery.   Put a small fuse (3 amp) in the battery positive lead.

 

Connect the battery negative to the ground pin of the instrument cluster.

Touching the right turn, dash light, left turn, or high beam pin should make the corresponding lights come on.  There are four dash lights.

Apply power to the ign power in pin, and then grounding the oil light, ign light, should make those lights come on.

With power applied to the ign power in pin, grounding the fuel, or temp pin, should cause the corresponding gauge to go full scale. 

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