Jim Lane

I need you to help me see if this will work.

I need a Canadian Volunteer to try this circuit on their headlights.

It is very simple consisting of only 2 relays and I think it should work, I would have developed one a long time ago but since I have nothing to test it on I can only see it in my mind.

Here in the factory diagram you can see how the lamps are connected left and right in a conventional manner, the DRL module is connected to the harness through the Right side headlamp (I traced out the circuit in yellow highliter so it is easer to see) you can see that the DRL is connected to both Low and High Beam filaments, but I am not exactly sure why.

As far as I understand DRL's and there are different systems, the High Beam filament is being driven at a decreased output usually 70% by a PWM (pulse width modulation) signal from the DRL module.

This would account for the relay chattering when it was connected across the PWM's output.



This is the right side of the truck, at the top right you can see the DRL module and its connections.



This is the Light Switch, Dimmer and associated wiring.

Looking at the lower right hand side you will see:

Provision For Snow Plow Lighting

This is how I propose to control the headlamp relays.



How it works:
Both Low and High Beam relays are configured backwards compared to the relays on Federal (USA) sold trucks.

The headlamp filaments are connected to Term #30 Common, Term#87a N.C. is connected the the existing DRL circuit while Term #87 N.O. is connected to the battery and supplies full voltage and current.

You can see in my circuit the headlamps will remain in the factory DRL circuit and function properly as long as the headlamps are turned off but as soon as the low beams are activated the low beam relay will trigger and toggle the headlamps from DRL over to full power.

Use a Bosch, Tyco or other good quality 5-terminal ISO relay for this upgrade.

Term #30 = Headlamps
Term #85 = Coil ground
Term #86 = Coil + signal LOW BEAM L-4 16-Violet wire HIGH BEAM L-3 14-Red wire
Term #87a = factory DRL circuit from RIGHT side headlamp socket
Term# 87 = (+) 12-volts and circuit breaker

The relay trigger wires from each Term #86 of each relay will be connected to the Black 2-blade connector inside the cab above the base of the steering column up near the bulkhead connector, if my idea is correct you will not reconnect the opposite end.

Use a 12-volt test light to determine which side of the connector to connect your wires to.



I need some of you to give this a try and let me know if there are any issues that I need to change in the design.

Once I know it works I can show how to wire up the harness.

Don't forget to use good sockets and make a good ground connection from the headlamps to body.

Also make sure the DRL power it taken from the RIGHT side headlamp socket or it will not work.

02/25/2013



Jim

crazzywolfie

seems like the 92 and newer trucks do not have the provision for plow light connector. from the wiring diagrams i looked at that is a 91 and older thing.
this is the diagram for a 92 and 93

tech-eh

nice write up jim
yes i have a 1990 truck thats plowing now harness is as described

sssssss
sssssssssss
sssssssssssssss snowing in Mississauga

will look in to it when I get back from north bay in a few weeks

Jim Lane

Not a problem,
If the connector was not installed then all you need to do is to locate an accessible section of L-3 14-RED and L-4 16-VT wire above the steering column and then cut them, then I would terminate the switch (power) side using insulated Female Spade Terminals .



And the opposite side using the male counterpart.


When installing the terminals I would strip and tin the stranded wires using good solder first and then crimp the terminals to them using a good T&B crimper or equivalent.

Then the 2 wires connected to the Low Beam and the High Beam relays would terminate with insulated Male Spade connectors and simply plug into the mating connectors you just installed leading to the switch.

If you ever had a relay fail you could always reconnect the 2 wires and plug the headlamps back into the factory sockets and be on your way with headlights again.

You could either use spade terminals or crimp/solder and shrink tube in a flat 2-pole molded connector, (get 2 of them) you could order from Amazon but make sure to get one that has at least 14-gauge wire.

This all might sound complicated but really it is not.

Jim

Jim Lane

All of you guys running snow plows, how do you have your axillary plow lights connected into the trucks electrical?

Are they tied into the factory lighting or do you have them on toggle switches?

You do have to have them don't you?

There sure is some fancy equipment out there now, I always wanted to get a snow plow but it never gets below 50*-60* here in the winter in Southern California so if I want to see the snow I have to look up into the mountains.

If I want to get my feet in the Snow I have to drive 30 miles North up the mountains from my house, or if I want to go the Beach, I have to drive 30 miles South from my house to Huntington Beach, both on the same highway.

If I want to go into Hollywood I have to drive 30 miles West and 30 miles to the East is pretty much the Desert.

My old neighbor used to drive a Cal-Trans 5-ton Dump Truck/Snow Plow up in out local mountains, snow plow at the top and rock knocker at the bottom.

Jim

crazzywolfie

ya but that would kind of take the plug and play idea away. now i think the DRL module high and low beam light wires hook into the headlight system at the passenger side headlight socket which is why there is 5 wires to the socket. wouldn't it just be easier to move the relays to the passenger side and cut the day time running light wires just a bit behind the factory headlight socket if i am going to have to find and cut wires? then you could just use a couple connectors to connect the day time running module directly to the new relay harness but be able to reconnect it to the stock harness if you decide to sell the truck.

also if i move the relays to the passenger side do you think it would be a good idea to wire the relay harness to the harness to pull power straight from the alternator? i know most stock trucks would see a bit of a voltage drop between the alternator and the battery.

thrashingcows

Any Canadian 1st gen'er actually done this? I have been wanting to do this to my crewcab, since it's running all 93 Canadian wiring, and the DRL work perfectly.

With the DRL is it possible to use the conversion systems that are available through E-bay etc. Just using the RH plug instead of the LH?



Ebay #131250038723

gyman98

I used the LH plug and have drl's that run the high beams at full power. I'm ok with that. Did the same with my 4th gen when I did hid's and run my high beams at full power for drl's. They are bright but not blinding in the daylight

thrashingcows

Thanks for the reply Ashley....Did you use one of the pre-fab kits...or Jim's diagram?

gyman98

It was done basically as per Jim's original diagram, pickup for low and high is off the drivers side plug. Drl's run the highbeams at about 5v but when they first come on they surge to around 8v. Enough to reach the minimum pick up voltage of a relay and way over the drop out voltage.

thrashingcows

OK I decided to try and be lazy....I ordered one of those H4 headlight relay kits off E-bay. Wondered about the quality of these kits so I paid $15 shipped....so not out too much.

Here are a couple pics of the kit I ordered....





Well decided to install it quickly and see what happened. My 93 donor was a Canadian truck, so it came with the daytime running lights...which still work properly. So I hooked up the system with the primary hook up on the passenger side, since that is where the main power for the DRL come from.

The high and low beams seemed to work fine. But when I shut off the lights, and then moved the truck to get the DRL to come on..(Yup it needs to sense movement or they will to come on). The relays in the system were buzzing like crazy, and only the drivers side would light up. The passenger side was very, very dim...just a slight glow in the bulb.

So guess it's a no go. But what really got me was that I was feeling the wires, and even though they looked like 10/12ga...they were really soft. So I decided, since I was not going to be using the kit, to open up the main power wire. Wow what a deception they have going on there!

Here is a 10/12 gauge piece of wire on teh left, and the "10/12ga" wire from the kit on the right.



I actually measured the wire strand and if it's 18ga I think you'd be lucky. All coating on the wire to make it look bigger then it really is.

So guess I'll be building one of Jim's headlight relay kits.

Jim Lane

My guess on the relays chattering are because the DRL's light the headlamps using a PWM signal from the module, for those who do not know PWM = pulse width modulation where the full voltage is pulsed on and off at a very rapid rate a very efficient way to dim lights, motor speed control ect.

The relay coils are chattering to the frequency of the pulse width.

The contacts on the relay would burn up quickly if the coil did not melt first.

This is why I designed the circuit to toggle the headlamps between the OEM DRL signal and full switched current/ voltage, I know the only snag is where you have to pick off the trigger for the relays but do not let that scare you.

I am only going off a schematic so I need somebody to try this and let me know.

Jim

thrashingcows

I will be attempting your wiring schematic soon. I will definitely update this thread with the results.

Thanks again for your advice and expertise.

mknittle

The writing on the fourth line down sat it all. I remember when Chinese junk was a boat

I really think you are better off making your own. If for no other reason it will fit better than a generic kit.

thrashingcows

Your right....I would have had to extend the wires regardless to make it fit properly. They long lead is only 60".