2018 Civic Hatchback EX Head Unit Stereo Wiring

nicksaurusrex

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Trying to wire up my Line Out Converter to the factory head unit (the CarPlay one). I’ve looked at all the wiring diagrams on here and they say position A23 on the wiring harness is supposed to be a red wire for the ACC power and position A13 is unused.

On my EX, position A23 is a yellow wire and A13 is a red wire. Which wire am I supposed to be tapping into for Accessory power to my Line Out Converter?

see images
Honda Civic 10th gen 2018 Civic Hatchback EX Head Unit Stereo Wiring 224FAA12-C922-466E-B7B5-ECBAD00BF882
Honda Civic 10th gen 2018 Civic Hatchback EX Head Unit Stereo Wiring 12BEC1CD-20B0-4279-B73B-8F36BB497F19
Honda Civic 10th gen 2018 Civic Hatchback EX Head Unit Stereo Wiring 7E376A8B-8B21-4D21-A2D7-482FBD49C635
 

bikejog

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The diagram you have is for the 2/4 door. The hatch is different. The hatch diagram will say "rear door speaker" instead of "rear speaker". Keep searching for A23 and you'll hit the hatch one eventually.

If I recall, A13 and A23 are both labelled as ACC. You have to check out the wiring diagram to see what the differences are.
 

BrandonSmith

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This is the stereo wiring diagram for a 5-door EX hatchback (FK7). I'm typing what's in the picture so others can find this through search.

Use the Red (A13) for acc as the yellow (A23) is for the rear camera.

If you're wiring the LOC to the front speakers:
FL+ is Light Green (A15)
FL- is Light Blue (A16)
FR+ is Grey (A17)
FR- is Purple (A18)

If you're wiring the LOC to the rear speakers:
RL+ is Blue (A5)
RL- is White (A6)
RR+ is Yellow (A7)
RR- is Brown (A8) - NOTE: There is another brown wire in this connector (A3) so don't mix them up!
Honda Civic 10th gen 2018 Civic Hatchback EX Head Unit Stereo Wiring 1607392349366


Honda Civic 10th gen 2018 Civic Hatchback EX Head Unit Stereo Wiring 1607393530876

Honda Civic 10th gen 2018 Civic Hatchback EX Head Unit Stereo Wiring 1607393337663
 
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bikejog

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Wonder what the A23 RR_CAMERA_ACC_DIODE input is. I know it's connected to the ACC relay and the reverse light relay via two diodes. But what's use for?
 


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nicksaurusrex

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This is the stereo wiring diagram for a 5-door EX hatchback (FK7). I'm typing what's in the picture so others can find this through search.

Use the Red (A13) for acc as the yellow (A23) is for the rear camera.

If you're wiring the LOC to the front speakers:
FL+ is Light Green (A15)
FL- is Light Blue (A16)
FR+ is Grey (A17)
FR- is Purple (A18)

If you're wiring the LOC to the rear speakers:
RL+ is Blue (A5)
RL- is White (A6)
RR+ is Yellow (A7)
RR- is Brown (A8) - NOTE: There is another brown wire in this connector (A3) so don't mix them up!
1607392349366.png
Looks like I wired it up correctly as I tapped power from the red A13 wire for the LOC converter and my ground / speaker wiring is correct.

After wiring up the LOC and Sub and turning the ignition to Accessory or On, I noticed there’s a high pitched buzzing or ringing sound in the passenger side of the engine bay. Sounds like a pulsating noise. I promptly turned the car off and heard a rapid clicking like a relay switching back and forth. Never heard these sounds prior to install. So I disconnected the battery, disconnected power to amp from the battery, reconnected battery, turned the ignition to Accessory and On and heard the same noises. Have you heard of this happening?

Really hoping I didn’t screw up some electronics..
 
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BrandonSmith

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Weird, considering there are no electronics on the passenger side of the engine bay (only the starter). I've heard something like that when my battery was too weak to start the car (it was like 10.5V and too weak to hold relays open so they just kept clicking). Also when I forgot to reconnect a ground wire for my fog lights. Check battery voltage. Were you trying to start the car (brake+push button)? or just putting it in ACC?

Other than that:
  1. Is your amp grounded to an unpainted part of the vehicle? double-check both ends of that ground cable and make sure they are seated properly. Ground cable should also be less than a meter (39") long.
  2. Disconnect the (+) amp power wire (with the car OFF) and see if the issue persists the next time you turn the car on
 
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bikejog

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The alternator is on the passenger side of the engine bay. You could be overloading it.

EDIT: I guess you didn't start the car up did you. In that case, NVM.
 
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nicksaurusrex

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The alternator is on the passenger side of the engine bay. You could be overloading it.

EDIT: I guess you didn't start the car up did you. In that case, NVM.
I did not start the car. Got scared haha but maybe I should start it to let it charge up the battery? I just had it disconnected for about 12 hours while I installed everything. Didn't think it would cause an issue though.
 
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nicksaurusrex

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Weird, considering there are no electronics on the passenger side of the engine bay (only the starter). The only time I've heard something like that is when my battery was too weak to start the car (it was like 10.5V and too weak to hold relays open so they just kept clicking). Check battery voltage. Were you trying to start the car (brake+push button)? or just putting it in ACC?

Other than that:
  1. Is your amp grounded to an unpainted part of the vehicle? double-check both ends of that ground cable and make sure they are seated properly. Ground cable should also be less than a meter (39") long.
  2. Disconnect the (+) amp power wire (with the car OFF) and see if the issue persists the next time you turn the car on
I had the battery disconnected all day while doing the install - about 12 hours. I wouldn't think it would lose much power in that time but the amp wiring is 4 guage for the power and ground cables so maybe they're drawing too much power without the alternator charging up the battery.. unsure. I should probably see how much voltage my battery has now.

I had not started the car since disconnecting the battery, just turned the ignition to Accessory and On mode - was too scared to start it after hearing unfamiliar noises.

1. My amp is grounded to the factory ground by the trunk latch. This is the same spot where the tail lights are grounded. I tested resistance and that point had about 4 ohms resistance which I didn't think would cause a grounding issue. I didn't sand the paint back there since it was a factory grounding point. My ground cable is roughly 36 inches so should be good there. I made sure to crank down that factory grounding bolt that I stuck the amp ground on to ensure a good connection. I also made sure to tighten the other end of the ground cable securely to the amp.

2. I disconnected the positive amp wire from the battery and hooked the battery back up, turned the ignition to Accessory and On (did not start the car) and heard the same noises and same clicking after turning the car off.

Not sure where to go from here other than sand down the paint around my amp grounding point and checking battery voltage.
 


bikejog

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I did not start the car. Got scared haha but maybe I should start it to let it charge up the battery? I just had it disconnected for about 12 hours while I installed everything. Didn't think it would cause an issue though.
Neah. I wouldn't start the car if you hear the high pitch noise. I would try to find out what caused the high pitch noise before I try I to start the car. Disconnecting the battery for 12 hours wouldn't damage the battery. I sometimes leave my car sitting for two weeks and it starts right up every time.
 
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nicksaurusrex

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@bikejog @BrandonSmith battery’s at 12.66 volts so not sure what else it could be. I’ll sand down that amp grounding point for good measure in a couple days and get back to this post.

Thank you both for all the good pointers and if you have more, fire away
 

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I had the battery disconnected all day while doing the install - about 12 hours. I wouldn't think it would lose much power in that time but the amp wiring is 4 guage for the power and ground cables so maybe they're drawing too much power without the alternator charging up the battery.. unsure. I should probably see how much voltage my battery has now.

I had not started the car since disconnecting the battery, just turned the ignition to Accessory and On mode - was too scared to start it after hearing unfamiliar noises.

1. My amp is grounded to the factory ground by the trunk latch. This is the same spot where the tail lights are grounded. I tested resistance and that point had about 4 ohms resistance which I didn't think would cause a grounding issue. I didn't sand the paint back there since it was a factory grounding point. My ground cable is roughly 36 inches so should be good there. I made sure to crank down that factory grounding bolt that I stuck the amp ground on to ensure a good connection. I also made sure to tighten the other end of the ground cable securely to the amp.

2. I disconnected the positive amp wire from the battery and hooked the battery back up, turned the ignition to Accessory and On (did not start the car) and heard the same noises and same clicking after turning the car off.

Not sure where to go from here other than sand down the paint around my amp grounding point and checking battery voltage.
Ground is good. If it's good enough for the factory ground, it's good enough for your amp. The threads of the grounding bolt are bare metal, so you don't need to sand anything.

I'm at a loss. What's your remote connection looking like to the amp? Straight from A13 to the amp?

Grasping at straws (and don't be offended), but are the (+) and (-) wires going to the correct connections?

It really sounds like a grounding issue to me. I wired up my fog lights and I forgot to connect the ground and it did the same thing.
 
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nicksaurusrex

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Ground is good. If it's good enough for the factory ground, it's good enough for your amp. The threads of the grounding bolt are bare metal, so you don't need to sand anything.

I'm at a loss. What's your remote connection looking like to the amp? Straight from A13 to the amp?

Grasping at straws (and don't be offended), but are the (+) and (-) wires going to the correct connections?

It really sounds like a grounding issue to me. I wired up my fog lights and I forgot to connect the ground and it did the same thing.
See video below of sound in engine with ignition On.

Yeah, made sure the threads were bare metal when installing.

Power wire to LOC is straight from that A13 wire (red) to the LOC. This gets me thinking I should double check my splices as I used the least reliable of splices (quick connects) for the wiring. I also realized there’s a possibility of having crossed the connections on my splices between the power, ground, and speaker wires since I did not insulate them individually. The splices are pretty close together.

No offense taken - I triple checked my head unit to LOC and amp wiring to make sure I got all connections correct. I even have notes during my install so I could not forget.

 

bikejog

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Could it be the climate fan? Shut the fan off and see?
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