High Beam wiring on Liberty

I'm adding driving lights to my '06 Liberty, have 'em mounted and wired to a relay with power. All I need now is to wire the relay to the high beams, so they're activated with the regular high beam switch. Easy enough, so far.

My plan was to jump the relay "switch" wire to the high-beam terminal on one of the headlamps. But it turns out there's a problem with this, in that its setup with daytime running lights (I'm in Canada), which use the high-beam filament on low power for DRL. So there's always a "live" on the high beam terminal...

So I scratched my head and came up with Plan B. This is originally a US vehicle, converted to use DRL when imported to Canada, which I believe involves removing the High Beam Relay, inserting a low beam relay, and programming the control module appropriately. So I reckoned there should still be a "switch" live on one of the contacts in the Junction Box where the High Beam Relay used to live. So I tested them out, there are 5 slots (3 vertical, 2 horizontal). According to the wiring diagrams, contact 86 (vertical nearest rear of the vehicle) should be the one that switches the relay. But I found it's live, even with the vehicle off and no lights on, as are 4 of the other 5 slots (the last being earthed). One of the slots' voltage *drops* when I flash the lights, so it looks like the system switches the relay by *removing* live, rather than adding it. So there goes Plan B.

My plan C was to go direct to the steering column switch, I believe White/Lt Green is the wire for high beam. But thinking about it some more, this is just a contact switch, it has no clue whether the lights are on high or low beam. (And I don't want to have to hold the stalk all the time while I'm driving at night :-)

I really would prefer to have these synced with my regular high beams, but am running out of ideas. Does anyone have any clues where I might find a "live" which is only "live" when the high beams are on?

Thanks!

/M

Reply to
Moro Grubb of Little Delving
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I don't have the liberty schematics but on the ZJ the DRL module runs the high beams but at a lower power (probably pulsed DC). There should be a module somewhere back from the high beam connection at the headlight. On the drivers side of this module should be the normal high-beam feed.

On the WJ it's a relay and BCM (Body Control Module) reprogramming. And from what I've read it looks like your Liberty has the same setup. Still though there should be a way to tap the high beam feed from the steering column.

You need a schematic to tell where to tap in.

Not much help, but for the OEM lights.

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a good idea of where to look and that it's not very simple. :/ Thinking off the top of my noggin here, so hold on eh. :)

Stop by the local jeep dealership and ask to see the wiring diagram for your jeep. Your trying to find the wire from the stalk you will need to intercept and how it works. Could be a ground or voltage loop.

Another option.

Assuming they didn't change much in the stalk. Grab a multimeter and find the large connector from the steering column. Check each one as someone turns the high beams on and off. Only one should come on with the high beams. If you don't have a multimeter you should get one. Terribly handy and they are fairly cheap.

Important bit here. Your going to have to run the wire into the engine bay to get at the offroad lamp relay. You need to put an inline fuse just after the tap you make into the steering column. The reason is if the line shorts at the firewall or inside the engine bay it could damage the swith in the stalk. Not sure exactly how big a fuse you will need but it's not likely to exceed 300mA so a 1/2A fuse would be a good choice.

Getting to the engine bay.. this might help.

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Reply to
DougW

That might work, but getting at it might be difficult. You might have to use a second relay if it doesn't have enough power or if it uses a switched ground.

I've used tiny relays from RadioShack like this one.

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away from reed relays, they tend to stick. Let me grab that service manual and have a look.

Sheesh.. They use a special module to run the light bar. That's what I was afraid of.

And the stalk switch is special too. So that idea is out.

I wonder how much the lightbar switch costs? That would keep the installation factory. Page 8W-50-16

I'm thinking buy all the parts but the factory lightbar. Could be a bit expensive though. :/

Hold the phone.

After long consultation with my cat we might have found a possible solution. Are your parking lamps on all the time or are they only on when the lights are turned on?

If they don't run all the time there might be a solution.

Page 8W-50-3 in that pdf I'm going to pick on the relay drawing on that page.

Here is the idea. Use a relay to disable the lights when the low beams are on. And use the power from the parking lights to run the offroad lamps relay.

Run a wire from the low beam (one of the lamps that does not double as a turn signal) to the coil on a relay (I'd use one identical to the others under the hood with a good socket) and ground the other side of that coil.

So on a new relay, pin 85 will run to the low beam (via a fuse) and pin 86 will go to ground.

Now run pin 30 to the parking lamp 12V (Page 8W-50-8) and pin 87A to the 12 input for your offroad light relay that is supposed to sense the high beam.

Basically what it's going to see is 12V when your lights are on but your low beams are not. i.e. when the high beams are on. :)

Everything else wires the same. You still wire the offroad lamp power back through the relay to the battery.

So any time the lights are on the parking lamps are on. But when the low beams are on your off-road light relay will not get power.

Gosh that sounds confusing.

ASCII art time. _____________ | new relay | | | PARKING >----|->(30)common | LAMPS | |

12V when on | (87) >-|-//nada | | | (87A)>-|-------->"High Beam" sense | | for the offroad Ground >-----|->(85)coil | light relay | | Low Beam >---|->(86)coil | 12V when on |_____________|
Reply to
DougW

^^^^^^^^ oops :/

make that "run a wire from a parking lamp that does not double as a turn signal.

Reply to
DougW

Thanks again, Doug. Clearly you have a devious mind :-)

So, as I understand it, the second relay is powered by the parking lights (only energized when lights are on), and switched by the low beam.

But:

This is in reverse to normal, where pin 85 goes to ground, so this means the relay's "switch" (coil) is wired in reverse. (ascii art shows this backward, i.e. in the "normal" configuration, where the driving lights would come on with low beam). So this will mean that when the low beams are on, the switch is energized in reverse, i.e. "open". But does that mean that when the low beam in *not* energized, i.e. there's no current flow through the switch circuit of the relay, it'll close? If that is so, then all relays would by default be "on", which they're not... Or am I missing something?

/M

Reply to
Moro Grubb of Little Delving

Yep, that's the idea.

close, but not quite.

All the coil does is move the switch, there is no "backwards" so to say. The coil is just a magnet.

Best to take one apart and look at it physically. This site should help.

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When the low beams are on, the coil is energized causing pin 30 to connect to pin 87.

When the low beams are off, the coil is relaxed causing pin 30 to connect to pin 87a.

If you feed the parking lamps 12V to pin 30 (common) then only if the parking lamps are on and the low beams are off, will that power flow to pin 87a.

pin 87a then in turn connects to the relay that came with your kit at the same place it expects the "highbeam"

_____________ | kit relay | | | 12V >----|->(30)common | Battery | | | (87) >-|---> Offroad lights | | | (87A)>-|-//nada | | | (85)coil>-|-----------o/ o----->Ground | | Inside switch From (87a)>--|->(86)coil | new relay |_____________|

Reply to
DougW

Thanks, that does make sense. Thanks also for the link.

My confusion arose from looking at the (cheap) relay they sell in the driving light department of my local Canadian Tire, which has 2 (two) 87's, and no 87a. So its a simple on-off with 2 outputs, one for each light, rather than a toggle between two alternative outputs. I need to shop for a "proper" relay...

Doug, I much appreciate your extensive assistance with this.

/M

Reply to
Moro Grubb of Little Delving

Try RadioShack, but CT should have those relays. Just get a cross reference for your existing fog or AC relay. Same thing. You can wire them just using spade terminals. Another source is a truck parts store or your local truckstop gas and parts station.

Shouldn't cost more than 6-7$ CDN for the relay.

not a problem.

Reply to
DougW

Been cogitating a bit on The Plan...

One problem is that if I get power for the relay off the parking lights, and use the low beam to toggle the relay to "off", then the driving lights would be on when the lights are on park (v "headlights on/low beam"):

Headlights on, low beam on --> DLs off Headlights On, Low Beam off --> DLs on ...so far so good, but Parking lights on, headlights off --> DLs on ... not so good.

But having learned what I didn't know yesterday (thanks again, Doug :-), I now know how to toggle the relay by "removing" power.

From my original post:

I think I'll go and revisit that contact... If it drops to 0v, and remains "dead" as long as the high beams are on, then it's exactly what I need. I can drop the plan for the second relay, and just use 87A (on a "real" relay, powered from the battery) instead of 87 to power the driving lights..

Which brings up one last question: This will effectively mean that the relay coil is live at all times except when the high beams are on, including when the car isn't running (i.e. ignition off). Is that A Bad Thing? Will it burn out, or kill the battery over time? (I'm guessing not, as it looks like the old HBR ran this way...?)

Thanks,

/M

Reply to
Moro Grubb of Little Delving

Durn, your right. :/

Could stack another relay in there, but that's starting to get ugly fast. The final relay would pull from the high beam line and preventing the DLs from coming on if the high beams were off.

I'd find out what the factory switch costs. :)

Maby tapping the HighBeam lamp is a better idea....

I gotta get some shuteye.. work tomorow. :( If I get a chance to go over the schematics I'll try to come up with another idea.

Reply to
DougW

Well, that isn't going to work either. The lamp is an LED that gets ground through the instrument cluster electronics. Tapping into that (although possible) would require quite a bit of care. Not something I would recommend if you haven't worked circuitry before.

The multi function switch is out too. It just provides a ground pulse each time you change between high and low beam. The body control module gets this and switches between high and low.

The DRL relay is a solid state device that essentially pulses the high beam (think AC) so it's not as bright. So a conventional relay hooked to the brights would just chatter.

I think your stuck with getting the factory switch and module if you want it to be 100% legal. :/

The more I read that service book the happier I am that my ZJ doesn't have all that computerized stuff.

Sorry, but I'm tapped for ideas.

Reply to
DougW

Thanks Doug. Did you read my last post all the way through? Here's a possible solution, assuming a relay will survive its coild being energized almost permanently:

I think I'll go and revisit that contact... If it drops to 0v, and remains "dead" as long as the high beams are on, then it's exactly what I need. I can drop the plan for the second relay, and just use 87A (on a "real" relay, powered from the battery) instead of 87 to power the driving lights..

Which brings up one last question: This will effectively mean that the relay coil is live at all times except when the high beams are on, including when the car isn't running (i.e. ignition off). Is that A Bad Thing? Will it burn out, or kill the battery over time? (I'm guessing not, as it looks like the old HBR ran this way...?)

/M

Reply to
Moro Grubb of Little Delving

Didn't read it all the way.

It's a shared circuit. What you are seeing is a low current pulse (square wave) that is used to pulse the high beam when your in DRL mode and a solid 12V when your in high-beam. I doubt that source is enough to run a relay and could cause problems with the body control module.

In the non DRL model the BCM provides a ground signal on that line to run the conventional high-beam relay. I suspect it was done this way to prevent folks from simply swapping relays to disable the DRL.

I think a relay will draw too much power from the body control module. Put the meter on AC and see what it tells you. Remember, the DRL module is a solid state relay. It does not require much power at all to switch. The BCM is most likely a transistor output which will have a max limit in the milliamp range.

That doesn't mean it can't be useful, just that to use it will take some custom circuitry to tell the difference between DRL and High-Beam. If you have ever worked with ICs (CMOS in particular) I can help you figure out how to build a circuit that can do this. This is when having a scope and other tools becomes handy.

Reply to
DougW

.. This might be overkill ..

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ear bleed time.

4081 is a CMOS AND gate. There are 4 gates in the chip so 1/4 and 2/4 are just two of the gates.

This chip can run on 9-18V so it can be powered directly from the vehicle and doesn't take doodle for power. There should be 12V at that the empty High-Beam relay location. 30 or 85 and ground is any chassis metal.

The first gate simply isolates the DRL relay. It charges the capacitor while the resistor drains the capacitor. The diode is there to keep the cap from being drained backwards, (one way valve)

The second and gate is reading the voltage on the cap. There is a threshold where it will think there is a logic(1) and will turn on. That kicks the transistor and then the relay.

Think of it this way. The cap and resistor is like a bucket with a hole. The pulses are like turning the tap on and off and on and off. When the high beams are full on (tap full on) the bucket will overflow and trip the second gate.

The problem now is figuring out what value to use for the capacitor and resistor. That's going to depend on what the input is in DRL mode and High-Beam mode.

Reply to
DougW

Long ago I asked: "Moro Grubb of Little Delving" wrote in message news:N_wal.18357$ snipped-for-privacy@newsfe12.iad...

Here's what I ended up doing:

1) Got a live off the parking light circuit, and ran it through a toggle switch to the relay for the driving lights. So I can turn 'em on and off with the switch when the parking lights are on, but they'll always turn off with the main light switch 2) Between the toggle switch and the Driving light relay I put another relay activated by the Low Beams. So the live from the switch goes to 30 on this second relay, and 87A goes to the driving light relay. So Low Beam breaks the circuit and turns off the Driving Lights.

So now:

1) The Driving lights will only work when the car (parking) lights are On. (No chance of flat battery from forgetting to switch them off) 2) When I turn on the headlights, I'll flip the switch for the driving lights. This turns them on, but they will only get activated when the low beams are off, i.e. when the high beams are on. So dipping the high beams will automatically toggle off the driving lights, and vice versa. 3) Potentially, when only the parking lights are on, the driving lights could also be on. That's what the toggle switch is for. (to turn them off)

This doesn't give me exactly what I wanted, because I still need to flip the switch to activate the driving lights, but they'll toggle on and off with the high beams, which was the main objective.

Thanks again for all the help and advice, Doug!

/M

Reply to
Moro Grubb of Little Delving

switch to the relay for the driving lights. So I can turn

Not a problem. I've got to admit though that Jeep did about everything they could to make adding off-road lamps a major pain in the arse.

Reply to
DougW

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