Maugutus

I noticed a few similar threads with the same problem.
It goes like this, one day your driving, you rev to a somewhat high rpm and your battery light comes on. You pull over and your car dies. When you look the alternator mounting bolt is loose, or the whole alternator has fallen off! So what do you do? You mount the alternator again with the same bolt, tighten the belt and start the car. It barely starts, wont rev past 2000 rpms and has almost no power. You just fried your ECU!!

Here's how to fix this problem and prevent it from occurring again! If this hasn't happened to you, it might, so follow these steps.

1) Remove the power steering for easy access, you will need ample space to properly ground your alternator.

2a) Remove the alternator mounting bolt replace with the mid sized one in this pack itemIdentifier=730234&_requestid=255355http://www.autozone.com/autozone/acc...questid=255355

2b) Use a locking washer that fits the mid sized bolt in the 3 pack, apply threadlocker purple to the thread of the bolt when replacing. Tighten to around 14 ftlbs (20 at most)

3) Reground the alternator using a wire like the one in the picture 16 gauge is ok. Ground it to the front timing cover bolt so it doesn't interfere with the power steering as pictured below.



4) Replace the charging wire, with a larger 8 gauge wire (optional for less resistance.) Install a 100 amp fuse on the charging like closest to the alternator. This will be the second failsafe, the first being the proper ground as shown above.

5) Loosen the belt (in case it wasn't already) and apply threadlocker purple. Retighten the belt to specs.

6) Replace power steering assembly.

7) Replace ECU (if fried, this is one of the LAST steps, do not take the chance to fry another ECU. I almost fried a second one if not for the ground on the housing.)

8) Reflash the ECU to match the key. That's how Brickell Honda does it here in Miami.

I have one non-vtec ECU in case anyone needs it, they are somewhat hard to come by in Miami for manual cars.

The alternator mounting bolt is the ground for the alternator, if it falls off or loosens the resistance will shoot up and the resulting voltage surge will burn through the underdash fuses and fry the ecu (it may not blow a single fuse because the current has not overwhelmed them.) Think of what would happen if your car was on and you removed the negative battery terminal, the car would try to ground through other means and fry things!!

Let me know if I forgot anything or if I can help anyone in anyway. This is my first writeup.

em2-matt

If your problem was like mine then the new ecu should work. I ended up taking mine to the dealership and they told me the fuse box under the dash needed to be replaced and I knew that wouldn't work but they swore to it and of course, it didn't solve the issue. So after that they got me a second hand ecu hand reflashed it and sure enough this was my problem. Hope that helps.

eviee1973

Honda had some manufacturing/installation issues with this, when my 2004 was about 8-9 months old, this bolt came loose. Only noticed due to the fact when the ac compressor came on, the drive belt was slipping and squealing.

freedom240188

Ive just had same problem battery light flickering at hi revs then on constant with engine light flashing on ignition and running with a stutter/hesitation and so on ecu would not respond there was a nack to get it to link up but no codes stored ect so I guesed ecuso got a second hand ecu for £41and then a reflash for £45 al done but they did say it didn't connect first time had to try it 2 times

the hole problem was a bad earth from alternator to engine ive just earthed alter to body incase bolt rattles loose and bugger my new ecu be safe comin problem on all civics 01-05 as all have same bracket lol

Maugutus

The new ECU worked perfectly. I made the writeup in hopes some people will avoid this mess, or repair it properly so it doesn't happen again to them.

Maugutus

Yeah, it sucks, but if you ground it like the pic shows it wont break anything if the bolt slips out.

I don't know how these 7th gen Civics have so many problems... The seats the, gauges, the alternator, the head...

Try_hard_diyer

Hi,

First post to HT so apologies in advance for any muck ups in my info or statements.

Vehicle: 2005 Honda Civic LX 1.7L Sedan

My situation is nearly the same as the ones above. Pulling out from a side street then tried getting up to speed (high RPM) for fast moving traffic then I notice a bunch of the dashboard lights turning on and flashing then my car starts losing power to the wheels. Roll through an intersection and managed to pull off to a side street.

Turned the car off then waited a bit. Tried to turn the car back on, engine turned over, RPMs go to about 500, dip to 100-ish, back to 500 then engine dies. Dash lights remain on and I hear what I later find out is a solenoid repeatedly clicking. Promptly turn the car off.

Got a multimeter and checked the battery, 12.64V seems okay. A friend of a friend's mechanic comes by and doesn't know what is wrong. Bring it back to his shop. He tries to scan the CEL code - no dice. He takes out the ECM and tells me its fried. However he also told me I needed a new alternator...

I decide to hold off on commiting to any repairs. I figured out the car is now in "limp mode", running rich (the smell of fuel was strong), can't get any power to the wheels and none of my dials are working. I figured out I can drive in 2nd gear so I was able to get up to about 40kph and get it to my driveway (only 5 blocks away).

I was suspicious of the alternator problem so I got my multimeter and tested the battery voltage while the car was running, after the 14 RPM dips and solenoid clicks. Under load the battery voltage was 13.5V so I "think" the alternator is doing its job - for now.

On my ECM the numbers are 3, then the label is ripped destroying the next 3 numbers and ending in zero, followed by PLM-C74. Ordered an ECM off ebay 37820-PLM-C74 (was cross listed for A74 for federal vehicles??) for C$132 and getting it shipped here in a few days.

I feel comfortable replacing the alternator by myself. I've done the belts and water pump before, got stuck at crankshaft bolt but then finished it after that.

Apologies, long story short, would it be worth my time and money to replace the alternator before installing the new ECM or possibly re-tighten the alternator as well as the grounding procedures above?

On top of that I have done a good amount of electronics soldering (through-hole and SMD) so I found out if you remove two EEPROM ICs from the damaged ECM and solder them back into the new ECM I don't have to get the ECM flashed by Honda. Good or bad idea? Risk versus reward, I'm torn. I have a feeling the dealership is going to give it to me good, $100 - $200???

I would really appreciate any suggestions or info to verify if this is a good plan of action. Thanks in advance!

NDNV

Your alternator may be failing, even though you tested the voltages. Common problem on these cars is a failing alternator. Also concentrate on the grounding bracket and the adjustment bolt for the alternator. I have personally gone through these issues as well as many other owners.

redrocket87

Maugutus when you said " 4) Replace the charging wire, with a larger 8 gauge wire (optional for less resistance.) Install a 100 amp fuse on the charging like closest to the alternator. This will be the second failsafe, the first being the proper ground as shown above.
There wasn't a picture of how you did it, did you take out the original wire and replace it with a new 8 Ga wire and put a inline fuse on that wire as close to the Alternator as possible?

redrocket87

So I phone the dealership's service department and I ask them what I'm looking at to have a used ECM flashed to put in my civic. The rep goes and asks, comes back and says you can't do it. However I can buy a new one for $975. I say no that's OK. I call the parts department and ask them if they could flash a used ECM so I can get my car going and he tells me you can't flash a ECM and reuse it in another car. Really I say, so since everyone else is doing it why would you say that. I imagine so you can sell your new ones for a Grand! He says I probably read it in some forum written by people who don't know what they're talking about. So I go down to the shop where I got my head gasket done and they say $73.50 + tax.

prodjay10

The dealer isn’t in the business of selling or reusing old parts. It’s like the snap on guy telling me it’s illegal to program my own keys.

awbill

Hey Redrocket,
Did you replace the charging wire with the 8ga wire that the OP recommended? And did you put/install an inline 100 amp fuse in that new 8ga charging wire?
I wasn't clear on that part of the OP's post.
Thank you, I appreciate your help/reply.
I will post my results as well, to continue this extremely helpful thread.

Thanks again, aw

Bryce De Waal

Hi I am having the same issue, except it keeps happening... About 2 months ago my car was misfiring slightly once in awhile and was not a big deal until the alternator came loose about 2 weeks ago which killed the ECU. So I remounted the alternator and ran a headbolt through the other side with the header removed, and added a nut to the other end with a ground strap to the body. I got myself a new ecu and she was running fine. I notice the misfires again and then the car would randomly enter limp mode and rev limit around 3k. (ive already replaved crank sensor, cam sensor, map sensor, cleaned egr, replaced pcv, cleaned iacv, replaced all coil packs and spark plugs) Just today it started to enter limp mode except the tach started to go out... as soon as that happened I heard the horrible sound of that blue relay behind the glove box ticking and sure enough... the ecu is dead again except this time my alternator is STILL MOUNTED! Im using the same one that this happened with but it is still mounted and the groundstrap is fine....... what is going on here I really need help..