Hello everyone. I have a 2004 civic ex that I was driving on the highway and while I was driving I had lost vtech as if the oil was low. I put oil into the car and still the engine would bounce at high rpm. I continued to drive it home and while at 70mph the engine died and restarted instantly into limp mode.

Pulled over, restarted the car, battery light stayed on. It would only go into limp mode if the engine cut out and I kept driving.

Got home tested alternator and battery everything was fine. Posted about it on another forum and here is where I am.

The alternator bolts weren't full tight so I tightened them and the lower alternator bolt broke so got a new alternator. Did all my grounds (ECU Ground, Chasis, and the transmission).

The battery light is still on. The car starts no problem. It idles. But randomly it will cut off and restart right back up. When this happens I hear the main relay click.

I don't think it's my ECM because I only go into limp mode very rarely. If the car cuts out and restarts it's usually not in limp mode. But if I try to drive it at a higher speed than say 45-50 and it cuts off and restarts I might be in limp mode.

I've also changed the ELD. Maybe it's the MCU for the light? But why the cuttoff/restart?

I notice sometimes if I hit the break it will do it, sometimes it wont.

Any advice?

 

I have DTC codes 2 (2 dome flashes) and 5 (5 dome light flashes)

 

Replace the main relay? When it cuts off, do you lose all power inside and out, no hvac etc? It's sounds mechanical, like an electric connection that jiggles just right on bumps at higher speeds or braking.

 

It's the same sound on the relay as if I turn the key to on (II). So I assume the car is instantly dying and restarting. It happens at idle. The car will idle find and then randomly out of no where completely die and completely restart.

Sometimes it will die and not restart. If that happens when I am driving it will be in limp mode and I'll lose temp gauge and rpm.

 

Very strange. But the temp and tach are only available when the BCM is powered with key in the ON (II) position. You might have a failing ignition key cylinder. hard to say without solid multimeter evidence as the cars experiences the problem. I'd try a new main relay first.

 

So what about the battery light being stuck on? Also would I know it's the ignition by wiggling the key? Like I just drove it an hour at around 50MPH there and back. The engine would cut out randomly and the green D light on the dash would disappear for a few seconds and I would have no power and then when it came back on everything would be fine. When it cuts out for those few seconds the battery light turns off and the CEL turns on. Then when it comes back the CEL goes away and the Battery light turns back on.

One time a few weeks ago it shut off while driving and was stuck in limp mode and there was a huge burning smell from near the ELD.

Also what about the DCT codes 2 and 5 saying there is a short in the YEL wire going from MCU to ECM?

 

I'm not sure on any of that. They're all vaguely connected but not dirrectly coorelating. Change something, reground the engine, replace the relay, until you change a part of the equation you'll keep having the same issue.

 

if the charging light is on that almost always means the alternator is bad and parts store alternators are junk

https://www.rockauto.com/en/catalog/...generator,2412

you can get a Pure Energy reman from rockauto for cheap or a Denso that is OEM

Pure Energy alternators come with free 1 year roadside assistance

https://www.rockauto.com/en/moreinfo...425451&jsn=373

when the Pure Energy comes you just buy a return label from rockauto and put the old in the box and put the label on and send it back and you will get your core back minus the small amount for the return label

then clear the codes and drive it and see if the codes come on, if so, have it scanned for codes

 

My understanding was with the ignition in the on position (II) if you unplug the alternator 4 prong wire it should turn off the battery light if it's the alternator. My light doesn't ever turn off unless the car goes into limp mode. Unplugging it doesn't turn the light off, so it can't be the alternator.