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Deciphering a door lock schematic (another car)

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Old May 21, 2019 | 07:29 PM
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Default Deciphering a door lock schematic (another car)

Thought I'd post here if someone can help me figure out door locks on another family car.... Schematic is shown below.....

This car has a secondary unlock circuit where 2 presses of the key fob unlocks passenger and hatchback. Haven't checked but might also work by turning door key twice (which would make the name of the relay more understandable)!!! Anyway, the unlock function is failing. I believe the "2-turn unlock" relay is failing. My hope is to bypass it with a new one. (Because it's built into the gdam fusebox! ARRRRGGGGHHHH!)

What I'm trying to figure out is the blue, black and "Hot" terminal. If I call this the "slave" side of the relay, what do you think happens here? Wish I had a FSM for that car, but I don't. I would assume the relay triggers the door lock actuators. The question is where it's by ground or by feeding power? I would assume black is the ground for the door locks? OTOH, what do you think blue is for? I would have thought it's the lead to the door locks while black is the ground that's completed via relay energizing? Why is would there be an extra power terminal on each relay too?

Hmmm....

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Old May 21, 2019 | 09:12 PM
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Just for fun what are you working on?
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Old May 22, 2019 | 12:35 AM
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Originally Posted by Kevova
Just for fun what are you working on?
It's a Kia. The three terminals nearest "2-turn unlock relay" are what I'm trying to figure out. Seems like the NO position wouldn't have ANY pathway. And, that the opposite position/pole would be the pathway to trigger the actuator.

Seems like it should connect power (thru the actuator) to ground...which I'd think would be black OR blue. Haven't figured out why both black and blue wires exist.

(I'm making the assumption the circuit appears in a NO state Will try to find color-coding for the actuator next.)

NO = normally open
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Old May 22, 2019 | 07:27 AM
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There likely a reciever module or BCM which recieves switch and remote signals. The module sends ground signal to relays. 2 unlock relay unlocks passenger doors. Can you access rear of fuse box?
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Old May 22, 2019 | 08:16 AM
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It seems Kia have door lock troubles. The blue IMO only sends unlock signal to passenger doors actuators. It's using a central locking relay only locks all actuators. Relays can't be swapped?
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Old May 23, 2019 | 03:51 AM
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I haven't picked up the daughter's car to look at (and repair) this issue. BTW....THANKS for the replies! Posted in TWO Kia forums on Monday....still nothing. (Guess we know lots of those fart-can owners just don't know diddly! LOL)

Seriously....Posts I've read say the 2-turn relay is hard-wired. PIsses me to no-end. Think of the owners who succumb to junction box r/r at a cost over $1300! WOW....Does that mean Toyota is still winner/champ of reliable? :-)

OK...NOW I'm going to be serious. The post above is close to what I'd determined. I had BRIEFLY considered jumping the white/blue wires but worried the extra load might blow another "hard-wired" (DS unlock) relay and complicate matters. Who knows what the amperage rating is for the primary unlock relay AND what the passenger and hatch actuators require? So, the external relay option is what I felt safest.

Without looking back at my OP, My biggest confusion is the positive "feed" into each relay. I assume all three relays have positive going to the activated/energized side of the relay? And, that the relays "feed" 12V to the actuators for activation? The confusing part is the relays seem to "rest" on ground. I can't see a reason for that -- even if an alternative source can trigger the actuators (like key vs lock/unlock switch)? That's because a secondary application of 12V would APPEAR to direct "short" to aforementioned ground! So....why wouldn't the relay's "rest" in NO position on a blank terminal?

(Here I digress.....If the actuators are reversing polarity, it brings to mind a circuit I built 10 years ago. I used a wiper motor to drive masking on my movie theatre screen. To reverse polarity, I had a relay on each of the two wiper motor wires. The setup swapped polarity at BOTH ends...along with a limiter to kill each circuit. As such, I was having trouble with how BOTH ends of the actuator(s) reversed polarity with single relays?)


Edit: Oh Yeah! If I apply 12V to the blue wire, it seems likely the all doors and the hatch should unlock? This would verify wiring of external relay but I want to make sure I can't "fry" some component of the car in the process! Of course I would cut the blue wire and apply voltage to the "car side" of that wire...meaning the end presumably running to the actuator. Promised the kid I wouldn't make the issue worse! And...I do NOT want to buy/replay a lock actuator!!!! Or even something else I didn't foresee hooked up to blue. (Can't find complete schematic online. Wondered if a local Kia would cough it up in lieu of DUMB NON-REPLACEABLE RELAYS!!!!
Thanks IHateBarkingDogs! Let's see if YOU are confused by MY confusion! LOL

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Old May 23, 2019 | 01:07 PM
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Originally Posted by GREGGPENN
Thought I'd post here if someone can help me figure out door locks on another family car.... Schematic is shown below.....

This car has a secondary unlock circuit where 2 presses of the key fob unlocks passenger and hatchback. Haven't checked but might also work by turning door key twice (which would make the name of the relay more understandable)!!! Anyway, the unlock function is failing. I believe the "2-turn unlock" relay is failing. My hope is to bypass it with a new one. (Because it's built into the gdam fusebox! ARRRRGGGGHHHH!)

What I'm trying to figure out is the blue, black and "Hot" terminal. If I call this the "slave" side of the relay, what do you think happens here? Wish I had a FSM for that car, but I don't. I would assume the relay triggers the door lock actuators. The question is where it's by ground or by feeding power? I would assume black is the ground for the door locks? OTOH, what do you think blue is for? I would have thought it's the lead to the door locks while black is the ground that's completed via relay energizing? Why is would there be an extra power terminal on each relay too?

Hmmm....

Grounding 1 RED/ORG locks all doors.
Grounding 2 BLUE/ORG unlock drivers.
Grounding 3 BROWN unlock unlocks passenger and hatchback.

Wires going down goes to actuatores in doors.
All should normally be grounded thru relays and give 12V when relay is active.
You can loose functionallity both from loosing ground and from not getting 12V.

Last edited by JoBy; May 23, 2019 at 01:10 PM.
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Old May 23, 2019 | 02:42 PM
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Originally Posted by ihatebarkingdogs
Take your diagram and draw-in the actuators. Connect the driver actuator between the red and white wires. Connect the others between the pink and blue wires.
The actuators are NOT grounded at the actuator. Current flowing in one direction locks, and the opposite direction unlocks. I'm confident that this is the way the locks work, as this is a VERY common lock circuit. It's even used in the 93-96 C4, although the 3 relays are contained within the CCM.

Study the diagram with the actuators drawn-in. You seem focused on the second turn relay rests at ground, but ALL THREE RELAYS rest at ground. Both pairs of actuators have each end grounded at all times. Applying B+ at any of the 3 relays causes those actuators to operate in that direction (lock or unlock).

Note that the LOCK relay powers ALL the actuators. One more (the drivers) than the second-turn does. All the relays are probably the same, so the lock relay has survived powering all the actuators. . Doubtful that adding the additional actuators to the first-turn relay will fry it. At least not right away. It may last the ownership of the car.

I spent considerable time yesterday understanding the circuit, writing, then editing multiple times, my post. Including the pin-outs for adding the external relay. I know it would work. The caveat is that you have to be sure you're cutting / intercepting the correct wires on the fuse/junction panel.

You'll get it. The point to understand is that the current flows THROUGH the actuator. One polarity locks. The other unlocks.

I attached a .pdf of the door lock circuit in a F250. It has the actuators in the diagram. It has three relays for the locks. The actuators are 2-wire, reversing polarity. It functions the way your KIA does, except for a slight difference in the way driver unlock rests at ground. The idea is that you can see it is a reversing-polarity scheme. If it confuses you further, ignore it.
Thank you for an example power lock diagram. That is very helpful! Now I see each relay serves as a ground for the actuators -- when another relay is energized. Makes complete sense! I don't know if that's how I wired my movie screen 10 years ago -- but, if I didn't, I should have! Thanks.

The car's symptom is increasing intermittent unlock function for all doors EXCEPT driver's door. Lock functions still work correctly. When I applied "extra" voltage by jumping the Kia's battery, unlock function increased about 30%...meaning it started working every 3 or 4 attempts. That means the 12V or ground connection (on it's circuit board) is failing. I won't attempt to diagnose or repair that. 12V can't be "bad" going into the junction box because all other functions are working. If I assume red or pink serves as ground for "secondary" doors when the 2-turn relay is fired, guess I should verify pick and red connector are solid (going into the junction box).

It's just as likely the relay itself is failing -- which is born out by other owners posting the need to replace their junction box -- to cure the same problem. Of course, I'll try to locate and verify the "onboard" relay is not replaceable before jumping it with another external Bosch unit.

If the brown wire comes from the door lock assemblies, do I need to be concerned with keyless unlock operation? Is it possible the relays are built onto a logic unit for keyless....forcing me to trigger the external Bosch with the DS unlock relay? Or...is it way more likely (as in your attached example), that a "generic electronic module" provides keyless operation -- just as an aftermarket system would do?

Last edited by GREGGPENN; May 23, 2019 at 03:00 PM.
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Old May 23, 2019 | 02:57 PM
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As far as confirming my diagnosis, it seems I should verify ground on the RED and PINK connectors (when "at rest"). And, I should verify strong 12V going to the blue wire when the door unlock switch is activated. If I find no/weak 12V (which is what I anticipate), I will proceed with the external relay installation.

Also, as previously mentioned, it seems I ought to be able to unlock the secondary doors by applying 12V to the blue wire (after cutting it's connection from the junction box)!
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Old May 24, 2019 | 04:41 PM
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Originally Posted by ihatebarkingdogs
I read both of your latest posts 3 times each. I'm not going to attempt to quote or dissect. You have it right. the tests and actions you propose are correct. Go for it.

I doubt there are any internal connections on the brown wire. When you install the external relay, cut the brown wire is a way that you can reconnect it if you need to. then any internal connections will be on the brown wire to the new relay. That the brown wire is still attached to the original relay should make no difference.

I had a feeling the Super Duty diagram would help. And it was easy, as I own a Super Duty and have all the wiring diagrams in my files.

Now you have a weekend project. Tell daughter to bring the car over along with a 6-pack, and stay for dinner. Cheers.
Yeah...it looks like I had a typo or two....(lick "pick" vs "pink" ... and ... my vague reference to the unlock/lock switches in the doors). Again, the big mystery is that they use opposing relays to serve as ground. Had the backside of my movie screen been more accessible, I would have looked at it...and possibly realized I'd done the same thing. It's definitely the obvious choice for a reversing polarity circuit!

I added a "like" to your post with the schematic. I also want to convey a BIG extra THANK YOU after learning you spent a lot of time of this. I know it takes a while to determine all connections and convert that to a relay's terminals. And, I appreciate leading me to where I was headed. Once again, thank you!

Ironically, I still haven't gotten a meaningful reply in EITHER of the Kia Forums I joined on Monday. In addition to the reverse polarity/grounding mystery (that I was slow to figure out), I wanted to verify the pin, location, and function of the blue wire. There are multiple blue wires routed into (a single "pin" on) the same connector Kia owners use to patch in aftermarket keyless systems. Hopefully it's THE blue wire from the schematic in my OP. Assuming the external relay restores proper function, I'll probably post the solution in those Kia "FAQS" sections to help other owners avoid a potentially high-priced and unnecessary junction box replacement. I still think it's a major screw-up that a power door lock system doesn't have easily accessible and replaceable relays!

I almost don't want to post the solution "over there". BOTH forums require approval for new members THEN a 10-post minimum before you can include links and pictures. Talk about a major headache -- just to communicate in a forum! Makes me appreciate this forum that much more! I know it's due to the issue of spamming....but Geez! LOL

The only other "mystery" I probably SHOULD solve is the power-supply Kia owners tap into to add aftermarket keyless. It's not identified in their post(s) so I don't what circuit it s...or it's amperage limit. I also haven't a clue what amperage 4 lock door actuators draw. I plan to splice into that underdash power supply anyway, trigger the locks a few times and see if the lead wire feels warm (and/or blows a fuse). If not, I will assume that circuit is sufficient to power those 4 actuators -- in addition to it's normal function. I suppose that means I'm lazy for not wanting to create a new, inline-fused power supply straight from the battery! Especially since she's considering selling it for another bigger dog-friendly SUV. (They have two dogs...one as big as Marmaduke!!! LOL) BTW...I can't even get a visit out of the deal. She's already moved to Omaha, on vacation, and left me the car to fix before they get back! The things we do for our kids!

Last edited by GREGGPENN; May 24, 2019 at 04:43 PM.
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