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head light switch & trans


Pabloairmale

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Head light switch turns on high beams. Iam not sure if this truck has a colum control high beam or the light switch is a 2 position switch.  Also want to ask about the trans slop on my truck.  feels like 3rd gear is out the pass window. is there anything i can do to make it a little tighter? Thanks 

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The headlight switch only sends power to the headlights both low and high beams. The headlight relay selects if high or low beams are on.

 

The headlight relay only has 2 possible positions ON or OFF. In it's OFF position the high beams are connected. This takes some thinking about but while driving around with your headlights off during the day the high beams are selected by the relay but without the headlight switch being on nothing happens. The power to the relay to activate it comes from the parking lights. The headlight switch has 2 positions and 2 separate circuits. Pull out the first position and the parking lights come on. Pull out the second position and the parking lights and the headlights are on. As soon as the parking lights come on the headlight relay is powered and depending on the position of the high beam switch (part of the turn signal switch) which grounds the relay, changes from high beams to low beams if grounded and remains on high beams if not.

 

 You have what is aptly called the 'Monkey Motion' shifter on the F4W63 in your truck. Accumulated wear adds slop.Ta7fVAo.jpg

 

WOgiN7j.jpg

 

#8s are cone rubber bushings. Try adding washers to help clamp them together and support the shift lever.

 

 You may be able to replace the #16 washer with a thicker one to remove some slop and also the #15 bushing while apart. Probably have to make something.

 

Pin #19 and clips #18 hold the fork to the horizontal striking rod. You may be able to slip a thin washer in there or I've heard pinch the forks closer together

 

 

In all cases the shifter parts must be non binding and free to move. You can tighten up the clearances but there has to be some for freedom of movement.

 

Morning Matt

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The biggest problem is accessibility. I had a 521 in the mid '70s. I was able to wrap a piece of wire around one of those areas to reduce slack. I think I managed a nut and bolt in there to tighten but the shifter was too stiff. Had to fit washers. Hell the shifter could be rotated all the way round in the cone washes. The shift pattern was anywhere in a circle the size of  basketball.

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The stock 521 headlight relay has four connections.  Power in, normally open contact, normally closed contact, and relay coil ground.  Internally in the relay, the relay coil is connected to the power in connection.   When the turn signal lever is moved forward, the relay coil is grounded.

 

The power in terminal on the headlight relay gets power from the headlight switch.  This is a thick red with yellow stripe wire.  On 521 trucks, the power to the headlight switch comes in from the fuse box on a thick red wire.  Earlier 521 trucks, with three always hot fuses, uses the red wire for both parking and headlights.  Later 521 trucks have a four always hot fuse box, and the parking lights get their own power supply to the light switch from the fourth always hot fuse in the fuse box.

 

When power is applied to the power in terminal, on the 521 headlight relay, from the light switch, if the relay coil is not grounded, power is then applied to the normally closed contacts.  From the factory, the Red with a black stripe wire is connected to the normally closed contact, and this wire goes to the two low beam headlights.

 

When the internally powered relay coil is grounded by moving the turn signal lever forward, the normally closed contacts are opened, and the normally open contacts are closed, switching power to that relay terminal.  this terminal is connected to the red wire with a white stripe. This wire goes to the four high beam connection on the headlights.

 

The headlights are grounded by a black wire that goes back to a black wire at the voltage regulator mounting bolt in the inner fender.

 

Later I will add a easy modification that makes your headlights brighter, and removes headlight current out of the stock 50 year old 521 fuse box.

 

Headlight relay modification:

Almost anyone who has a 521 for any length of time has had a problem with the headlight fuse, and the fuse box. There must be a reason the 510 uses two headlight fuses.

I did a "quick and dirty" easily reversible relay modification on this truck.

Here is a picture of an extra in line fuse holder I added to the fuse box,

FuseboxNewWire.JPG

 

The end of the orange wire hanging off in space will go to this extra blue relay, pin 30.

The OEM relay above the the word "limited' on the battery is the original headlight relay.

NewHeadlightrelay.JPG

 

And here is another picture of the wires on the fuse block.  The thick white wire comes from battery positive.

NewRelayB+.JPG

 

This extra relay is hooked up as follows.

Pin 30 gets power from the the added fuse.

Pin 87 connects to the terminal on the stock headlight relay that had the red wire with the yellow stripe on it, with a short jumper.

The red wire with the yellow stripe goes to pin 86 on the new relay

A short wire to ground goes to pin 85 on the new relay.

 

This additional relay takes headlight power out of the stock 521 fuse box. The headlight power also has to go through some connectors, the headlight switch, and into the cab, and back.

This is the voltage drop in the headlight positive side before the relay was added.

VoltageDropStock.JPG

 

And this is the voltage drop after the additional relay.

VoltageDropRelay.JPG

 

Edited by DanielC
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