01civyv3

Hey guys I have an 01 civic ex vtec obviously. The car was a vtec car from the factory however someone put a non vtec base model motor in it. Recently it popped the head gasket. So I pulled the head replaced the gasket and put a vtec head on the car since the harness was all still intact and fine. I fired it up a after the head gasket job let it sit and idle and after about 3 minutes of it running it died. Went to start it back up and the immobilizer key is flashing. Well I got to looking and forgot to snug up that ground that runs from the wiring harness to next to the t-star housing. So I snugged it up and thought maybe I fried the ecm leaving it loose. So I went to the junkyard and pulled an ecu out of an 01 civic ex 2dr automatic because that's what my car is. Replaced ecu and I towed it to the dealer to have them program it yesterday, they programmed it and said it fired up twice ran great and died after about 10 seconds just like they shut the key off. They didn't know what was wrong with it. So I brought it home and once again every once in a while it will Fire up and run great for about 10 seconds but die, go to crank on it again and they immobilizer lifht is flashing. Anyone ever heard of or seen this happen? Any tips or ideas would be appreciated

RIPSAW

Answer to this ought to be good if a dealer does not know what is wrong. Not a clue but there is an expert on here shortly. You would think if the ECM is protected from reversing the battery, what you did would not hurt it.

01civyv3

I believe the dealer was just lazy

ezone

Did you have the alternator loose or off?
Did you forget to tighten the alternator mounting bolts?
(It's so dang common to forget them and it causes so much damage $$$, there's a bulletin just for it.)

Do the gauges also act wrong when this happens?
Will a scanner or code reader communicate with the PCM?


Is the cam timing absolutely perfect, or is it one or two teeth off?

EDIT: go to crank on it again and they immobilizer lifht is flashing.
Is it flashing while you try to start it?
Is it flashing after the engine dies while the key is still in the run position?




Of course they did not know what's wrong with it.

They were merely reporting to you what they observed after completing the task you asked to be completed.

They would have to diagnose the problem----- after you agree to pay for the diagnosis.

Did they offer to diagnose the problem for you, for a fee?

01civyv3

nope I didn't take the alternator off. the timing is dead on. im completely lost.










I offered to pay for diagnosis and they told me that the only thing they had time for was programming and that they couldn't diagnose it because when that key light is flashing it wont communicate with a scan tool, however when it does start and run for the 10 to 20 seconds it WILL communicate with the scan tool. this is crazy

ezone

That's not crazy at all, and it answers one of the questions above




Ok how about the ground wires at the thermostat housing..you said you had left them loose....

Are ALL the surfaces clean and shiny for good electric contact, and the bolt is not only tight but also clean and shiny?

You didn't use a bolt that was a little bit too long so the bolt felt tight but the wires really are loose?

The two black wires on the eyelet are both good, not damaged or broken?

Braided ground cable is also clean and tight?

01civyv3

The immobilizer light IS flashing when you try to start it. When it dies the light is flashing with the key in the on position and if you hit the key right after it dies the light starts immediately blinking again also. Ive check them two grounds about 3 times now. I'll check again tomorrow

01civyv3

update. a good friend of mine owns a junkyard, he got an 01 civic ex 2 door car exactly like mine just different color in it ran so I pulled the steering column and ecm out of it and put it in my car so the key would match the ecm, put it in it took about a half hour and boom as soon as I turn the key on the immobilizer light is flashing and wont start it just cranks. also put a new battery in it yesterday. where do the ignition get ground from? I also wire wheeled the ground from the radiator support to the engine and the g101 ground that goes from the wiring harness to the t stat housing. also when you turn the key on you can take the car out of PARK without pressing the brake. im just lost and need help please

ezone

Sounds like it's time to get a good voltmeter and wiring diagrams for the immobilizer system and the PGMFI system (PCM) and check all powers and grounds for each system.

PCM: A4 A5 A23 A24 are all grounds, all ground @ G101 on the stat housing.
Immobilizer control unit gets its grounding through the PCM on the brown/yellow wire #1 terminal.

01civyv3

Haven't got a volt meter yet but when the immobilizer kicks in does it not let scan tools communicate with it? I've unplugged the crank sensor and and the tcc solenoid just to see if it throws a code and it won't communicate. It's doing the same exact thing with the ecm that the dealer programmed and the ecu and column I took out of the donor car I grounded my test light and both relays in front of the ecm have power in all of the connectors besides one connector on each relay. Also when you turn the key on the shifter will come out of park without pressing the brake but if you unplug the blue relay or unplug the Very top connector in the ecu then you have to press the brake pedal for it to shift out of park

ezone

Because the PCM went brain dead for whatever reason.

I wonder if one of the 5v lines is getting shorted to ground, effectively putting the PCM into a coma?


Sensors that use the 5v reference circuits:
MAP
Knock
TPS
EGR
FTP
I'd unplug each of those items and see if any will bring the PCM back to life. Unplug in any order, whatever is easiest to reach first LOL

NOTE: IF one of those happens to be the culprit, I can't tell you if the PCM would wake back up on its own or if it would need to have the key cycled off, or if the battery would need to be disconnected and reconnected to get the PCM to wake up.

The only one of those that originates in the top connector ("E") is the FTP (fuel tank pressure) sensor, it's on the EVAP canister under the car.
There is a lot of stuff wired in the E connector, maybe 20 different possible reasons it's making so much difference when you unplug it.



Is there any chance you could have pinched, cut, squashed, sliced, or otherwise damaged any wiring in the engine compartment when you did the cylinder head work? That seems to be the common point when all this trouble began, right?

01civyv3

Yes it's where it all began. I can't find any pinched squashed or broken wires anywhere at all.

ezone

Maybe mashed the knock sensor or something? It's pretty well hidden under the intake manifold on the back of the block.

01civyv3

well I figured it out, you were right I smashed knock sensor unplugged it and the bitch fired right up!!!!! thank you so much man

RIPSAW

Too good.....Ezone's the MAN