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Dan, Technician
Category: Honda
Satisfied Customers: 24584
Experience:  Independent Shop Experience, 2 Year Automotive Diploma, & Access to Information Database
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The ignition coil fuse on my 2008 Honda Civic blows every

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The ignition coil fuse on my 2008 Honda Civic blows every time I turn on the ignition.
JA: Do all the fuses have the correct amperage for the circuits they're in?
Customer: The fuse blew when I jumped out the high pressure switch in the ac circuit.
JA: Are you fixing your Civic yourself? What have you tried so far?
Customer: Yes I have disconnected the battery to reset the computer. I have pulled the ignition relay out and turned on the ignition. The fuse still blew immediately when I turn in the key
JA: Anything else you want the mechanic to know before I connect you?
Customer: I sent 12v through the pressure switch when I jumped it out.

Hello, my name is ***** ***** I'm here to help get your problem solved.

If the 15 amp fuse in location 18 of fuse box still blows with the ignition coil relay removed this means the fuse box has internally shorted out and needs to be replaced. Let me know if you have questions, thanks.

Customer: replied 1 month ago.
I'm assuming the ignition relay is J in the fuse box isthis correct

Here is a picture, let me know if you have questions. Thanks.


Customer: replied 1 month ago.
I pulled the ignition relay and the fuse didn't blow when I turn the ignition on. I replaced the relay and turned the ignition in and the ignition fuse blew.

This means one of your coils have probably failed, disconnect each coil one at a time to see one allows coil to stop blowing when unplugged then replace that coil.

Customer: replied 1 month ago.
Thank you it has 2 bad coil packs

I'm happy to help, let me know if there is anything else I can do. Thanks again and please do not forget to rate answer.

Customer: replied 1 month ago.
I still have The original issue of the ac not working should I troubleshoot that now or pay again for the answer?

You can continue replying even after paying but we can try to get that figured out now. Why did you jump switch to begin with? Does fuse still blow or did it only the 1 time?

Customer: replied 1 month ago.
I jumped the compressor clutch like I have in the past on some older cars to get the compressor clutch to engage. It engaged and was blowing cold air. So I then tried to send voltage through the pressure connector to see if the pressure switch was bad. That's when the coil packs failed.

Have you connected a gauge to make sure AC is properly charged?

Customer: replied 1 month ago.
I did connect the guages it appeared to have plenty of pressure for the compressor to kick in.

Have you checked codes in HVAC?

Customer: replied 1 month ago.
No I wasn't aware it even had codes on the ac.

Check them and let me know what they are, thanks.

Customer: replied 1 month ago.
There weren't any codes.

I'd go ahead and replace the pressure sensor, after that it may sound like control head but having a scantool to be able to view hvac data will be needed to know for sure. Let me know if you have questions, thanks.

Dan and other Honda Specialists are ready to help you
Customer: replied 1 month ago.
Thank you I think I will take it to the shop.

I think it may be worth the gamble with pressure sensor, let me know how it turns out. Thanks.

Customer: replied 1 month ago.
I replaced the coil packs the ignition fuse is still good but the car won't start.
Customer: replied 1 month ago.
It doesn't appear to be firing.

Is fuse blown again?

Nevermind, I see that you said fuse is good.

Check to see if black/white wire going to coil has 12v with key in start position, let me know. Thanks.

Customer: replied 1 month ago.
Ok it will be tomorrow before I get a chance to look at it. Thanks

Sounds good, let me know. Thanks.

Customer: replied 28 days ago.
I have found that it blows the fuse after I plug in the 3rd coil and wait a few minutes or it blows immediately if I plug in all four. It doesn't matter which order I plug them in. The circuit is being overloaded when all 4 coils are plugged in.
Customer: replied 28 days ago.
The black and white wire has 12v until the fuse blows on all 4 coil plugs.

Replace the coil relay and let me know if that helps. Also, are you using a 15 amp fuse?

Customer: replied 28 days ago.
Ok I will try that and yes I'm using 15a fuses.

Ok, let me know. Otherwise I'd imagine one of the coils are pulling too many amps. Does it start when only leaving 3 coils plugged in? Do coils seem to be getting hot?

Customer: replied 28 days ago.
the coils are getting hot. No I haven't tried to start it with just 3 plugged in because it blows the fuse within 15-20 sec.

If coils are getting hot I think you burned you PCM when you jumped pressure switch. New PCM needs to be install/programmed at dealership. The PCM is what activates the coils so if they are getting hot this would mean PCM is trying to activate them at all times. This is about a $600 repair at dealership which is probably your next best option. Let me know how it goes or if you run into questions, thanks.

Is vehicle auto or manual transmission? 2 door or 4 door? I can give you part number incase they try to charge arm and a leg for part.

Customer: replied 28 days ago.
It's a 4 door auto

Part number I have is 37820RNA68, it looks like these are also alternative numbers. 37820-RNA-A63; 37820-RNA-A64; 37820-RNA-A65; 37820-RNA-A66; 37820-RNA-A67; 37820RNAA67. I'm seeing some cheap ones on ebay but make sure dealership is able to reprogram a used on before buying if that is the route you take. Let me know how it goes, thanks .

Customer: replied 28 days ago.
Is the dealer the only one that can reprogram it or is there an alternative? How much should it cost to reprogram it?

It is about a hour labor to install/program. It cannot be programmed without being installed and dealer is pretty much only option. So first thing I'd do is call dealer and ask how much to have a new ECM installed/programmed and cost of part. If part is a crazy amount ask if they can reprogram a used one. If so, order one and have them install/program it. Let me know how it goes, thanks.

Customer: replied 28 days ago.
Thank you

No problem, keep me updated.