jessemspears

Car details:
2005 Honda Civic DX 1.7 Sedan

Incident details:
Driving to work, all my console lights and controls started chirping and flickering.

On the way home, battery finally died and my car came to a halt. Got out to check a few things and noticed the Alternator was loose. The bolt that holds the adjustment bracket onto the engine had snapped off.

I managed to get my bolt out and replace the alternator with a new one (why not). However now i've got a new problem to which ive only been able to find the term "limp mode"

Current situation:
from a cold start the engine barely idles and will cut off unless i give it some gas. In addition, i hear a clicking from the glove box (where my ecu is located). The clicking sounds is in sync with the batter light and engine light alternatively cutting on and off finally ending with my check engine staying on.

I can drive the car, but it burns rich and accelerates very, very, very slow.

I drove to a nearby shop and they told me they couldn't communicate with the computer and weren't getting any codes. So they suggested i replace the computer because it most likely shorted out when the Alternator broke loose. So i finally got my ECU out yesterday and took it apart to see if i could see any burnt up circuits. i did not notice anything burnt up. (but i'm not a professional)

My question:

Before i go buy a new ECU and get it flashed, has anyone ever heard of this? Does the ECU shorting out make sense or could it be something else? What else can i try to make sure im not about to waste my money.

Any guidance is very much appreciated.

GusBuz

Yes your ECU is dead. Specially if it cant communicate thru the DLC with a scan tool. Thats one tell tale sign that you have a fried ecu.

If you look at other threads talking about the alternator you will see that this is common when it comes loose because it grounds through the body and the ecu does not like this one bit, resulting in fried circuits inside the ecu.

Best route is to get a new ecu flash it, and also make sure the alternator is bolted on good. Then run the car and make sure you take care of any codes that might pop up. One more thing......Also check your fuses and replace any that got burned out.

ezone

Fix alternator problem FIRST because it will fry the next PCM (ecu, ecm, etc.) if you don't.....and that's not cheap.

OneJzSupra

I would test the alternator to make sure that it didn't fry the voltage regulator. You may end up needing to replace that and even the battery. I had an issues that fried the ECU, my Emanage blue, alternator and battery. I would look at doing the following:

Test voltage output of current alternator (anything over/under 14ish volts is bad)
replace alternator if needed
Test/charge Battery Voltage
Purchase need battery if needed
Reset computer
Disconnect Alternator (by disconnecting the alternator this will allow you to rule out any issues that would be caused by the alternator.
"Jump" battery with another vehicle and try and start the car
Take note to how the car is responding and whether it is still in "Limp Mode" or continues to run bad. That should give you an idea that the PCM is done for.
replace/test alternator (Including mounting bolts).
attempt to restart car and retest voltage output once again. Check for issues with "limp mode" on the PCM.
IF PCM issues are still noted replace PCM.

Hope that helps.

mac25

Check your fuses and relays first!

Just because there is no communication to the DLC (data link connector) does not mean the ecu is fried, you could have a blown fuse which is killing the DLC signal.

I'd say to fallow the above advice about replacing and testing the alternator and battery if needed, then check all fuses and related relays.

OneJzSupra

Dang it I meant to include this on my list of troubleshooting, thanks for the backup!

CRXTILLIDIE

When the alternator "broke loose" was it swinging by the cables. The alternator positive terminal cable has a little rubber boot on it to stop it from arcing with the housing. That old boot gets cracked over time and can start sparking. You're lose alternator has probably done a real number on that boot and possibly bent the cable's copper connector enough to make it sit even closer to the housing. Wrap up the bout with electrical tape before reconnection to terminal.

CRXTILLIDIE

I suggest this because I hope your ecu is fine and it's just a short to ground on alternator . Cause that would cause the symptoms described