My car: 2001 Honda Civic LX coupe.

I was driving home on Friday when my battery light came on. I continued driving the car until I was able to get off the Parkway in NJ when all of my gauges died and I lost power. I was able to nurse the car to autozone in hopes of a diagnostic. Unfortunately the car would not connect to their scanner. I got the car home and started researching what could be wrong. My initial guess was the alternator, which led to this site and a few threads on the issue. I tore into the car and found the alternator bolt hanging from the alternator mount.

I replaced the alternator, started the car and noticed all the same issues plaguing my car. All of my gauges were still dead and the car was still running in limp mode. Back online I found that the alternator bolt can come loose and ruin the ECM. So I ordered a replacement ECM and installed it today. Problem solved right?

Unfortunately I have all the same issues after replacing both the ECM and the alternator.

Again the issues I have: Battery Light, some relay clicking near the ECM, gauges die after about 30 seconds of running including temp, tach, speedometer. Also can smell noxious fumes not normally associated with the car.

My only thought is that the new alternator from autozone is crap.


Thank you in advance everyone.

 

I replaced the alternator again and still have the same issues. ill add a video once it finishes uploading from youtube.

Here is the clip:
Sorry about the music.. my radio reset >_>

 

I did have a loose/broken alternator bolt issue in the past. but just replacing the bolt and tightening the bracket solved the issue.

I did some reading on this issue as well and maybe you can find some areas to look into from the following from this site:

“Yes, I did resolve it.

Bolt for alternator ground came loose, alternator arced and damaged my coolant sensor and pin B10 on the ECU. I bought a new coolant sensor and replaced it (like $18 off ebay and literally 5 minutes of my time) and that fixed the temp gauge/idle problem. It did take a few days for it to start working though...not sure why.

I bought a used ECU off ebay for $90. Dug behind the glovebox and pretty much had it ready to be pulled out. Called a dealer and asked if they'd marry a used ECU to my car. They said yes and $200 later I had my used ECU in and the light is gone. Beats the $1,200 the other dealer wanted to put in a new one.

Also, my alternator and battery were replaced and were deemed 100% working (heck I drove it for months like that...light just stayed on). Sounds like you need a new sensor and ECU. Pull yours out to get the right part number.”


“I had the same problem It is possibly caused by a external solid state control device called ELD mounted in your engine compartment fuse box is about 36.00dls to replace, what it does it senses the load and then turns the alternator output on and off by grounding the reg output ....ok I personally did not like this system so I went into the 4wire plug connected to the alt and cut the white/green wire (the output of this circuit) and the problem went away if I replaced the ELD unit probably had fix the problem, this is a system designed to save fuel and at this time I do not think that is as important as saving my alternator and other components”


“The car is a 2005 Honda Civic lx, with a 1.7l sohc non vtec engine, and 5 speed manual gearbox. 142k miles. Two days ago, the alternator pivot bolt on my car sheared off, causing the alternator belt to fly off the pulley. The car died and lost all power while going thru an intersection. I had to have the car towed home. I bought a new bolt, and mounted everything back up. However the car seems to be in limp mode. It runs and drives, but poorly. It will barely rev and I hardly have any power. The exhaust smells rather rich as well. The rev counter and water temperature gauge do not work and my cel and immobilizer mil lamps are on. I did a little bit of research as to what could be the problem and I found out that the bolt and mount are what actually ground the alternator. When the bolt sheared, do you think an excessive amount of voltage arched to my ecu, frying it? I have tried resetting the ecu, by pulling the correct fuse (can't remember number) and removing the negative terminal battery cable, but it didn't resolve the problem. Any help figuring this out is appreciated!”


“Your ECU got fried when the bolt sheared off causing the alternator to move. You need to get a new ECU and have your keys programmed to it.”


https://honda-tech.com/honda-civic-2...ttery-3246894/

“also be aware that this is a ECU/PCM controlled alternator and if the alt goes bad it can damage the ECU . so your new alt seems to not work ,there is a TSB about this happening usually happens after T-belt is changed and the Alt bolts are left loose ,Alt is damaged due to poor grounding and it takes out the ECU control circuit.”

 

As a follow up I had the new ECU programmed by Honda and that fixed limp mode issue. Still have a battery light and the damn Engine Temp Gauge is not working. Following the advice here I replaced the ECT sensor with a new one but it didnt work and as a result my fans wont work as well. Also having a slight idle issue which might be related to the ECT sensor, not sure. :/

 

Could be a short or open wire in the ECT circuit. Here is how my manual says going about checking. If you don't have a repair manual it is highly recommended that you buy one. Best money I ever spent.


1. 7. Turn the ignition switch ON (II).
2. 8. At the engine wire harness side, measure voltage between the ECT sensor 2P connector terminal No.2 and body ground. (red/white wire on ECT connector to body ground)


Is there about 5 V?
YES - Go to step 9.
NO - Go to step 10.
3. 9. Measure voltage between the ECT sensor 2P connector terminals No. 1 and No. 2. (red/white and Green/yellow on ECT connector)


Is there about 5 V?
YES - Substitute a known-good ECM/PCM and recheck.
If symptom/indication goes away, replace the
original ECM/PCM.
NO - Repair open in the wire between the ECM/PCM
(A10) and the ECT sensor.
10. Turn the ignition switch OFF.
11. Disconnect the climate control unit 22P connector.
12. Turn the ignition switch ON (II).


1. 13. At the engine harness side, measure voltage between the ECT sensor 2P connector terminal No.2 and body ground. (red/white wire on ECT connector to body ground)


Is there about 5 V?
YES - Replace the climate control unit.
NO - Go to step 14.
14. Measure voltage between ECM/PCM connector terminal B8 and body ground.


Is there about 5 V?
YES - Repair open in the wire between the ECM/PCM B8) and the ECT sensor.
NO - Go to step 15.


1. 15. Turn the ignition switch OFF.


16. Disconnect ECM/PCM connector B (24P).


17. Check for continuity between ECM/PCM connector terminal B8 and body ground.


Is there continuity?


YES - Repair short in the wire between the ECM/PCM (B8) and the ECT sensor.


NO - Substitute a known-good ECM/PCM and recheck.

 

I know this is an old post but if it helps anyone DO NOT BUY AUTOZONES ALTERNATORS. I went through probably 10 of them including new and rebuilt ones. Get either a new or used or Honda alternator. By the way the failed alternators fried 5 ecu's