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Discussion Starter #42
So, I pulled the door panel. I do not recall ever having this item worked on, so it was odd to find the link to the key cylinder routed outside the protection guide. Hence why it would not lock. I was able to shift it to the proper position. It functions in both directions now, but the door lock knob switch still does not function. It always shows UNLOCK as ON and LOCK as OFF. I removed the door actuator to inspect. Removing the 3 bolts on the actuator was tough! The door lock knob functions up and down as it is supposed to and always has. Anyway, since everything appears to move correctly, it would appear the switch inside the actuator has malfunctioned. So, should I switch out the actuator? Or the actuator and latch? Also, is there anyway to identify what the 5 wires coming off the actuator indicate? I have attached a picture. Is one of them for the door lock knob switch? The yellow with red stripe on the 3 pin connector looks as if it could have been nicked previously. There was electrical tape around those three wires. Anyway, hate to buy a new actuator if this is a wire issue. If I could identify which wire represents the door lock knob switch, I could use a test light on it. Any thoughts?

Acutator Connectors.jpg
 

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I can't see the wire colors on the 2 pin connector but I'm guessing that's the lock actuator. It will get 12v and ground on it during lock or unlock and switch polarity to lock vs. unlock. It shows that they should be a yellow/black wire and a yellow/green wire. You can use a test light on this and it should light in both lock & unlock. If you used a meter you could see the polarity changing but if it works, it works.

The 3 pin connector is the door lock knob switch. This appears to be a switch input to the door multiplex control unit (MICU.) That means the door MICU feeds 12v out on the white/black and the Yellow/red wires and the lock knob switch in the actuator will will ground one or the other through the black wire. If it's stuck in UNLOCK all the time, that means the white/black wire is being pulled to ground all the time.

The first thing I would do is unplug the 3-pin connector and see if you get 12v on both the white/black and yellow/red wires. You won't be able to use a test light. You'll need to use a meter. Since this is a computer input your meter may even pull the voltage down a little if you don't have a real high impedance meter. If you have some voltage on both wires with your meter then the wires to the door MICU are good. I'd expect the same amount of voltage on each one and since the unlock signal is there that wire is obviously working so just make sure both wires match in voltage. Again, a test light won't work here.

Then, you can simulate the LOCK status by grounding the yellow/red wire and see if the scan tool changes. If you can get the LOCK and UNLOCK statuses to change in the scan tool by grounding the appropriate wire then you know everything is good and the switch in the actuator is bad.

Hope that all makes sense.
 

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Discussion Starter #45
Thanks. I just used the test light before reading and could see both the yellow/red and white/black had power. I believe I have a meter if that will provide a better indication. Would the best way to test the LOCK/UNLOCK status by grounding the yellow/red with a test lead?
 

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Discussion Starter #46
Sorry, not sure I understand the test procedure. Would I be running the yellow/red to the black return?
 

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Are you using an LED test light? That could be why your test light worked on those wires. Either way, if you have power there then you're good.

First question....When the connector is unplugged does the scan tool show both lock and unlock as off? If so, that verifies you're on the right wires.

The safest way to do a bypass test like this is to use a fused jumper wire just in case you happen to be on the wrong wire. If you have an incandescent test light you could also use that to safely pull those wires to ground. Technically, any jumper wire to ground should work as long as it's the right wire. All the lock knob does is ground those wires.

Yes, you could just jumper each of the wires to the black wire and that should do it, as well. You just want to see the status change on the scan tool when you ground out each wire.
 

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These are called a "pull down" design switch input. The computer (the door MICU in this case) sends out 12v and the switch "pulls down" the lock or unlock wire to ground and that's how the MICU knows the status of the lock knob.
 

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Discussion Starter #49
Success. With connector unplugged, both show OFF. Using the jumper, yellow/red to black LOCK ON, white/black to black UNLOCK ON. Looks like I need to replace the actuator. I can pick one up locally and get this back together today. Hopefully my tailgate will work.
 

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Nice job! If you can successfully change the status of the lock knob in the scan tool by manually grounding those wires then you know everything going to and from the door MICU is good and the door lock knob switch is not working. That switch is in the driver's door lock actuator.

I'm sure that will fix your tailgate issue. It doesn't lock since everything isn't showing locked. There is no lock actuator on the power tailgate models so this has to be it. It's definitely a problem and is the cause for all the lock/unlocking when driving. I'd suggest putting it back into that mode to verify that problem is gone, too.

So, diagnosis for a power tailgate that won't lock is replace your driver's door lock actuator. How about that one? The casual parts changer would have spent a lot of money before getting to that.
 

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Discussion Starter #51
FINALLY, THE TAILGATE LOCKS! AND THE SECURITY LIGHT BLINKS! Thank you for your patience and assistance. The scan tool was definitely key to identifying that problem. Quite tricky considering the door lock knob was actually still functional. Anyway, hard to believe the Honda dealer could not identify that issue with their scan tool, but I am glad to finally have a secure tailgate and the security features active again. I am new to ODYCLUB, but is there some way to comment on your help? Thank you again, it was a pleasure working with you.
 

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You should tell them you want your money back for the rear trunk latch and junction box! They should have been better than that but the dealer techs don't want to spend the time needed to get to the right diagnosis. They get paid flat rate for certain jobs. It may have taken more than an hour to diagnose this and they'd have to come back to you for more diagnostic time to which you may have balked.

I agree, though, that a dealer tech should have known this system much better than me. I just dug into the diagrams and used basic electrical knowledge I use on all cars.
 

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FINALLY, THE TAILGATE LOCKS! AND THE SECURITY LIGHT BLINKS! Thank you for your patience and assistance. The scan tool was definitely key to identifying that problem. Quite tricky considering the door lock knob was actually still functional. Anyway, hard to believe the Honda dealer could not identify that issue with their scan tool, but I am glad to finally have a secure tailgate and the security features active again. I am new to ODYCLUB, but is there some way to comment on your help? Thank you again, it was a pleasure working with you.
This is just a forum....it's not like justanswer or one of those sites. I do take Paypal though! 😉
 

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FINALLY, THE TAILGATE LOCKS! AND THE SECURITY LIGHT BLINKS! Thank you for your patience and assistance. The scan tool was definitely key to identifying that problem. Quite tricky considering the door lock knob was actually still functional. Anyway, hard to believe the Honda dealer could not identify that issue with their scan tool, but I am glad to finally have a secure tailgate and the security features active again. I am new to ODYCLUB, but is there some way to comment on your help? Thank you again, it was a pleasure working with you.
I also think a lot of this has to do with how well you can explain the issue to the service writer, and in what kind of detail. The key to this, after chasing the rabbit hole of the rear hatch circuit, was all the detail you provided on all the symptoms you'd seen. The security system not arming is what finally brought me to the right area to look at. For anyone else reading, always keep in mind that you know your vehicle best and every detail you've noticed can be critical to getting a diagnosis.
 
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