Headlight wiring help needed.

This thread is a spinoff of Dave89's (It's dark at night) thread about headlight upgrades. I didn't want to hijack his thread so I'm starting this one.

... I am thinking a simple, say, 82 ohm 1/2 watt resistor from the low beam + to the ground. If that works, then a really simple harness could be built to make it plug and play, weatherproof, etc.

I was about to order this headlight relay harness kit when I read about Dave having trouble with his headlight doors not working with his new lights. It reminded me that I will have the same problem if I install this kit. I still want to order this kit because it will take the load off the headlight switch and supply full battery voltage to the headlights. I suspect there is considerable voltage drop at the headlights because of the old headlight switch contacts and the marginal factory wiring.

I hope making this headlight relay harness kit work with the headlight door module is as simple as installing a resistor from the low beam circuit to ground because I think otherwise the harness kit will be plug and play without any modifications to the factory wiring. I'm hoping you guys will look at this kit and give me your opinions on it before I place my order. Any recommendations on what needs to be done to make it work properly to make the headlight doors retract would be appreciated.

Thanks for posting the wiring diagram Daniel. I was hoping that I could do it without cutting the factory wiring but in the end I might have to do that to get the doors to work properly.

I was wondering how you arrived at the 82 ohm value of the resistor. I looked in the FSM and didn't see it. Is that the resistance of the filament in the headlamp?...

No magic, but some speculation on my part. Somewhere in that monster thread from last year, it was determined that a relay coil resistance (80-90 ohms) was enough to allow the headlight door module to think the bulbs in the headlights were good and close the doors. In Daves case there is no relay harness involved. So I am thinking a simple resistor across the low beam to ground would work. (And probably one on the high beam side as well.) Wattage rating based on application of Ohms Law.

Guess I should buy a set of the Truck-Lites and try it out. (Birthday coming up soon too. )

[ATTACH=CONFIG]277579[/ATTACH]This is my solution. It can be done with two standard relays.

This solution would work too. I think a simple extension to it would allow making a harness to avoid cutting any original wiring.

I want to protect the headlight switch with the harness so I need figure out how to get the headlight doors working with it but I will probably go the cheap route with the headlamps when I replace them. No more than I drive at night I can't justify spending the big bucks. Probably Silverstars or something similar for me.

I want to protect the headlight switch with the harness so I need figure out how to get the headlight doors working with it but I will probably go the cheap route with the headlamps when I replace them. No more than I drive at night I can't justify spending the big bucks. Probably Silverstars or something similar for me.

Daniels suggestion and mine still run full power through the stock wiring.

The solution from last years harness thread was, in part, rewiring the trigger wire for the headlight door module.

Where is the best place to mount the relays for a headlight harness kit? Near the battery would be the most logical place but I don't see much extra space in that area that's available.

Daniels suggestion and mine still run full power through the stock wiring.

The solution from last years harness thread was, in part, rewiring the trigger wire for the headlight door module.

That's what I plan to do if I ever get aroundtoit. The spot I found to mount the box, is to the frame rail under the battery just in front of where the vibration damper mounts on an 89 if you know where that is. Makes for long wire runs, but out of the way and most water unless you go thru a deep puddle. There are some holes already in it you can mount to without any drilling.

Need to nip the concept of Daniel's mod running full power thru the stock wiring. Once you insert a relay and use it to run power from the battery to the headlights thru it, there is no longer the stress on the headlight switch and stock wiring.

That's what I plan to do if I ever get aroundtoit. The spot I found to mount the box, is to the frame rail under the battery just in front of where the vibration damper mounts on an 89 if you know where that is. Makes for long wire runs, but out of the way and most water unless you go thru a deep puddle. There are some holes already in it you can mount to without any drilling.

Need to nip the concept of Daniel's mod running full power thru the stock wiring. Once you insert a relay and use it to run power from the battery to the headlights thru it, there is no longer the stress on the headlight switch and stock wiring.

The headlight switch will not be helped by any thing you do in the engine compartment. It runs through a relay on the interior prior to the head lights, as can be seen in the FSM wiring diagram.

I ordered the headlight relay harness this afternoon. Once it arrives I will take photos of the installation. I'm hoping all the wires will be long enough so It will be plug and play without cutting or splicing.

I ordered the same today as well. I will be going with Mc_Reatta's recommendation to swap out the relay for the fuse [Found in cabin fuse box]. Have not used the headlights since the day of install. That should change next week as Daylight Savings ends. That means by December we will be dark at 4:30.

I really hate that...

Daniel I can't see a relay that takes the load off the headlight switch in the diagram you posted. Power is routed through the contacts of the low/high beam relay but those contacts are powered by breaker 21 through the headlight switch.

Daniel, you're misinterpreting the diagram in the FSM.

If you trace the power to the headlights in the stock wiring, starting at the circuit breaker and ending at the headlamps, you will find the current needed to power the lights (55 watts x 2 for silverstars low beam = ~ 8.5 amps / high beams ~10 amps) runs thru contacts in the switch, thru the hi / low beam relay contacts and on to the headlights. (Not considering line / connection losses or draw of the headlight motor module)

When you insert a relay into this circuit in lieu of the headlamps and run the power from the battery to the lamps thru it, the path thru the stock wiring changes to, from the circuit breaker thru contacts in the switch, thru contacts in the hi / low beam relay and ending at the coil of the inserted relay. Using one relay to switch both lamps this draw is ~ 13 volts divided by ~80 ohms = ~ 0.16 amp. That's a 98% drop in the current load thru the switch and stock wiring. I think the headlight switch would like that.

That's also why I recommend pulling the 20 amp circuit breaker from the fuse panel and replacing it with a modified 5 amp fuse. This will protect the switch and stock wiring and then you can use that breaker to fuse the power from the battery to the harness relays powering the headlights. (Those LED headlights may only need a 5 amp fuse too if that current spec is correct) The 20 amp breaker can provide enough wattage to power two 120 watt high beam lamps. Think if your using that much, your local airport will be calling you to turn off your landing lights as the other pilots can't find the proper runway!

Ronnie do you think the Red or Black box located behind the battery of the Reatta might be a good box to use to protect the relays? Also do you think there is room behind the battery for one more box?

I think the red or back boxes will be too small to hold two relays and connectors that plug into them. I was looking for a place to locate the relays this afternoon and I didn't come of with a good place yet. I think they need to be where they can be easily accessed for troubleshooting. The length if the wires will have a big influence on where the relays can be mounted. I'm thinking a 90* bracket mounted to the radiator support or fenderwell near the battery might be a good spot because it is fairly dry in that area. I didn't order an enclosure with my harness. The one I wanted was only available in white and I want one that is black. Something like this radio shack box is what I have in mind if I can find room for it.

If there is room, the area to the right of the red box near the strut tower would be the logical location for the relays so power could be tapped from the terminals in the red box.

Daniel, you're misinterpreting the diagram in the FSM.

If you trace the power to the headlights in the stock wiring, starting at the circuit breaker and ending at the headlamps, you will find the current needed to power the lights (55 watts x 2 for silverstars low beam = ~ 8.5 amps / high beams ~10 amps) runs thru contacts in the switch, thru the hi / low beam relay contacts and on to the headlights. (Not considering line / connection losses or draw of the headlight motor module)

When you insert a relay into this circuit in lieu of the headlamps and run the power from the battery to the lamps thru it, the path thru the stock wiring changes to, from the circuit breaker thru contacts in the switch, thru contacts in the hi / low beam relay and ending at the coil of the inserted relay. Using one relay to switch both lamps this draw is ~ 13 volts divided by ~80 ohms = ~ 0.16 amp. That's a 98% drop in the current load thru the switch and stock wiring. I think the headlight switch would like that.

That's also why I recommend pulling the 20 amp circuit breaker from the fuse panel and replacing it with a modified 5 amp fuse. This will protect the switch and stock wiring and then you can use that breaker to fuse the power from the battery to the harness relays powering the headlights. (Those LED headlights may only need a 5 amp fuse too if that current spec is correct) The 20 amp breaker can provide enough wattage to power two 120 watt high beam lamps. Think if your using that much, your local airport will be calling you to turn off your landing lights as the other pilots can't find the proper runway!

You are correct I looked at the relay and assumed it was the other way.

So I will provide a fix for the issue that should fix both issues, and can be used on after market or stock headlights. I believe there is an extra relay spot below the fuses on the 89 (I will have to check in a bit). If one was to place a relay to be controlled by the yellow wire 10 just before the high low relay it would allow the doors to open and close and take the load off the switch. Then all that would have installed would be a 12V+ to pass through the NO contact and on to the high/low relay.

Daniel

So after my last post I went out to the garage and installed an additional relay in the interior relay panel.

Short of it because I should be sleeping by now.

Used the yellow 10 wire to energize the relay coil; grounded opposite side or coil.

Removed the small orange/dk blu wire (from the headlight 20 circuit breaker) replace with a thicker gauge wire; spliced that wire to unused fuse spot (13 I think); connected the orange/dk blu wire to second side of the unused fuse (used a 5 amp fuse to run this part of the circuit)

The new thicker wire was than ran to the common input on the new relay.

Wired the normally open side of the relay (with the same gauge as the new thicker wire) to where the original yellow 10 wire used to be. (the headlights are now ran directly off the 20 amp circuit breaker and the head light switch see minimal current) I may see how small of a fuse I can get to work in the switch side but that will have to wait.

The head lamps do remain on for about five seconds after the switch is turned off. I have not dug into why this is, but it does not bother me in the least as the headlight doors close immediately when the switch is pressed. The doors work even with both lights unplugged.

I have a couple fuse/relay blocks I had been using for experimenting so the wires I installed all snapped into the factory blocks with no issues. So excluding a trip to your local yard to snag the wires this can be done in around two hours.

Daniel

I am curious how the headlight wiring mod now debated will work on the '88-'89 modules? I reread the long thread I was part of a year ago, sort of embarrassing actually. Many are determined to not modify the factory wiring for whatever reason and yet do other more obvious mods? The new low current draw headlamps available may actually make this a moot point, but if you do stay incandescent and provide full power, you won't go back to the stock setup. If I remember correctly, the headlight doors and illumination only work perfectly if the module trigger wire is rerouted. The coil in the relay may function as the drain, but needs to be in the 70ish ohm range and I believe it was drtidmore that cautioned the relay should be the type with a diode across the 85-86 terminals, but I believe they only will operate with the power and ground in one direction, which may or may not affect the current drain desired. I just don't know. In my case I found a circuit breaker (like the factory uses) for B+ ( with mounting tabs) located under the splash shield for the coolant reservoir worked very well and is almost invisible. Close to the red terminal box on the fender also. I located the two relays on the rear of the relay enclosure at the left front, so it is fairly close to where the trigger wire is and also the door module. I do not have weatherproof relays and the location is relatively dry but the weatherproof style are available with mating sealed wiring connections, like used on the firewall, and are very pricey, but you can find lots of them at the pick and pull, maybe with enough harness to do some of the wiring without splices. Just suggestions based on the involved process from last year. I know it took many twists and turns but the result is very similar to what is suggested above except for the module trigger wire. The result is actually pretty straightforward that anyone can duplicate.

I looked at the headlight kit I bought and also thought to myself that I could do this as well. What I decided to do was to order out the headlight kit, install it and then go out to Gibson's and look for a 2 place relay bracket [with relays] and splice in [with solder and heatshrink] the weather proof relays as you [2seater] have suggested. This will stop the need for a weatherproof box and give me a "factory" look.

Any opinions on that?

My objective is to find a simple solution that will reduce the load on the headlight switch and factory wiring. I would like to come up with an aftermarket headlight harness kit that almost anyone could install if they have normal hand tools and the ability to follow instructions in a simple tutorial.

Some of the solutions that have been offered that require cutting wires and moving them to terminal XX of a relay that has been added to the fuse box will work but the average Reatta owner is not likely to tackle a job like that. I'm not looking to find a solution that is the easiest and cheapest for me. I'm looking for a way the average Reatta owner can protect his headlight switch with as little trouble as possible. Simply unplugging the headlight connectors and then plugging in a new harness to power the headlights directly from the battery may not be doable but that would be the ideal solution. The harness kit that Dave and I have ordered looks promising but we might have just wasted ~$30. We should know in a few days...

I looked at the headlight kit I bought and also thought to myself that I could do this as well. What I decided to do was to order out the headlight kit, install it and then go out to Gibson's and look for a 2 place relay bracket [with relays] and splice in [with solder and heatshrink] the weather proof relays as you [2seater] have suggested. This will stop the need for a weatherproof box and give me a "factory" look.

Any opinions on that?

The relays on the firewall of the Reatta and likely others should be about what you want. I believe the bracket they snap onto is also removable. Depending on what they were originally used for, there will be more or less wires and the wire gauge will likely vary. It would be nice to get as much harness as possible and the ones with all five pins used if possible. You can always not use something you do have but can't use what you don't I think the brake pump has a sealed relay also.

Ronnie, I think that harness should work electrically, but as I mentioned in the other thread, it depends on the dcr of the coil. It seems that it needs to be at most in the low 70 ohm region. With this in mind, you might have to wire a small resistor in parallel with the coil. For example, my relay with the 97 ohm coil would need about a 270 ohm resistor to get the aggregate down to about 70 ohms.

Mechanically though, as I have mentioned before, you may find you need right-angle headlight sockets for clearance. It won't affect Daves Truck-Lites though, since they have the nice pigtail coming out the rear with a separate plug.

My objective is to find a simple solution that will reduce the load on the headlight switch and factory wiring. I would like to come up with an aftermarket headlight harness kit that almost anyone could install if they have normal hand tools and the ability to follow instructions in a simple tutorial.

Some of the solutions that have been offered that require cutting wires and moving them to terminal XX of a relay that has been added to the fuse box will work but the average Reatta owner is not likely to tackle a job like that. I'm not looking to find a solution that is the easiest and cheapest for me. I'm looking for a way the average Reatta owner can protect his headlight switch with as little trouble as possible. Simply unplugging the headlight connectors and then plugging in a new harness to power the headlights directly from the battery may not be doable but that would be the ideal solution. The harness kit that Dave and I have ordered looks promising but we might have just wasted ~$30. We should know in a few days...

What you want to do makes perfect sense to me. If the relays used can make the doors and lights operate properly, so much the better as the fly in the ointment is the yellow trigger wire in the factory setup. I don't know if it was ever pursued or not, but there was discussion of a mating adapter for the module plug that would allow the connection to be made without cutting or splicing. I know I did not get reliable results using just the relays, but we know more now about what level of resistance is required and some of the issues may have been of my own making. It looks like some good research is continuing. I certainly don't know if a relay with diode as suggested by drtidmore will have an effect on the ability to drain the module? That type of relay IS polarized on the coil so the two desires, circuit protection and voltage drain, may not be compatible. Takes a better analyst than me for that.

Thanks for doing the testing 944. It would be great if the relays in the harness kit have a coil resistance of about 70 ohm so no changes will be needed. If not adding extra resistance should be easy. I think clearance of the connectors might be a problem but won't know for sure until the harness arrives. I have found some 90* connectors just in case I need to order them Dorman 84790 Headlight Socket

... I have found some 90* connectors just in case I need to order them Dorman 84790 Headlight Socket

I have mentioned those Dorman sockets quite a number of times on these headlight threads over the past few years. They are what I used with the little harness I made for my Hella lights. (Needed for drivers side only.) Worst comes to worst, you could make a couple of these for your headlight harness.

That's a good idea. Where did you find the male ends?

That's a good idea. Where did you find the male ends?

Ebay.

Thanks!

So after my last post I went out to the garage and installed an additional relay in the interior relay panel.

Short of it because I should be sleeping by now.

Used the yellow 10 wire to energize the relay coil; grounded opposite side or coil.

Removed the small orange/dk blu wire (from the headlight 20 circuit breaker) replace with a thicker gauge wire; spliced that wire to unused fuse spot (13 I think); connected the orange/dk blu wire to second side of the unused fuse (used a 5 amp fuse to run this part of the circuit)

The new thicker wire was than ran to the common input on the new relay.

Wired the normally open side of the relay (with the same gauge as the new thicker wire) to where the original yellow 10 wire used to be. (the headlights are now ran directly off the 20 amp circuit breaker and the head light switch see minimal current) I may see how small of a fuse I can get to work in the switch side but that will have to wait.

The head lamps do remain on for about five seconds after the switch is turned off. I have not dug into why this is, but it does not bother me in the least as the headlight doors close immediately when the switch is pressed. The doors work even with both lights unplugged.

I have a couple fuse/relay blocks I had been using for experimenting so the wires I installed all snapped into the factory blocks with no issues. So excluding a trip to your local yard to snag the wires this can be done in around two hours.

Daniel

I shall wait for you to get your rest and look forward to getting some more detailed information of where you intercepted that yellow wire and how that supplemental fuse was wired into the 20 amp breaker circuit.

This certainly is a sophisticated solution and would appear very OEM, but alas, not what would be considered a simple PnP solution that most seem to be desiring.

First thoughts are the delayed turn off of the lamps is a function of the LED power supply doing its thing. Once I understand exactly how you wired things, can probably figure it out for sure.

I shall wait for you to get your rest and look forward to getting some more detailed information of where you intercepted that yellow wire and how that supplemental fuse was wired into the 20 amp breaker circuit.

This certainly is a sophisticated solution and would appear very OEM, but alas, not what would be considered a simple PnP solution that most seem to be desiring.

First thoughts are the delayed turn off of the lamps is a function of the LED power supply doing its thing. Once I understand exactly how you wired things, can probably figure it out for sure.

The wires needed to be accessed are the yellow and black with red wires behind the hi / low beam relay, and the orange with blue wires on either side of the 20 amp breaker.

I have not had that fuse panel out of the console, so I don't know how much slack and room is available to do the needed work, but I expect it isn't much. You could conceivably remove the contacts from the panel where needed and replace with new contacts with wires that you can pick up at an electronics shop. that would make cutting wires unnecessary if you have the desire. The two wires that need to be spliced into, (the black with red ground wire and orange with blue wire from the battery) could be handled with a quick splice which would not require cutting those wires.

Otherwise you can cut, splice and solder wires, but you will still have to get connectors to populate an unused relay socket, and fuse socket for the added relay and fuse..

imo it would be better if the relays were near the battery to reduce voltage drop.

IMHO the wire runs are sort of six of one, half dozen of the other. I certainly agree that keeping the runs as short as practical is a plus, but it is relatively simple to use a heavy gauge wire from the B+ to the relays. Heavy wiring to the headlights is a little more problematic since it must have a certain amount of flexibility to move when the doors rotate. Of course the wiring can be downsized near the lights, or the jumper harness can be used as suggested. Adding splices or connections introduces the possibility of voltage drop in themselves but careful assembly should minimize that. In my case, I used the factory style wiring using the yellow drain wire from the headlight module which is on the drivers side so my choices were more limited. It looks like satisfactory operation can be achieved without the drain wire so the choices are more open. It would seem the relays located between the headlights with heavy feed and ground to the relays would offer the best compromise electrically?