hildenhawk1992

2005 dx sedan 5 speed so i changed my motor the new one came out of the dame yiu and all that good stuff once it was in and i started it in ran for about 5 mins and went into limp mode somone told me to change the ecu ignition and ke so i got them from a junk yard all out of the same car and put it all in amd started it no problem it ran again for about 10 mins but my ecu was clicking every couple second and every time it clicked i would loose power and my tach would drop out now it is back in limp mode and my buddy came up with a honda scanner he was going to bypass it all for me and now no obd2 scanner will connect to the car and it is still in limp mode what can i do to fix it

mac25

It sounds like you have a few issues.

You made sure that the ECU you are using is from a manual vehicle and that it matches your vtec option right (vtec or non vtec)?

Secondly if the ECU is really clicking it is broken.
It may be the relays right in front of the ecu though, so make sure.

Also if you have no signal at the DLC (Data Link Connector/"OBDII PORT") then you probably have a fuse/relay or two burned out, check and test all fuses and relays related to starting and running.


You're first goal is to get the DLC to communicate, then we can tachle the rest after we get codes.

ezone

Fix the alternator that is not properly grounded (not bolted on tight, or maybe corrosion) before you go any further.
Loose alternator bolts are the most common cause of ruined PCMs on that car.

hildenhawk1992

i tried what you said besides test the relays as i dont no how to do that checked thw alternator cleaned it up and put it back on and also i unpluged the whole wire harness from the motor and cleaned all my grounds and the scanner still wont connect what do i do now

ezone

PCM lost the ability to communicate so that means it was ruined (consider it 'collateral damage' because it was damaged by the charging system problems);

Replace PCM,
program immobilizer to the new PCM so it will run the engine (or get the ignition switch complete with its matching PCM as you did before),
recheck all systems.

Unplug the alternator (4 wire plug) before starting the engine just so you can make sure the new PCM works. Then plug in the alternator, make sure it's not gonna screw up while it is running. If there is ANY sign something is wrong, shut it off before it ruins another PCM again.

hildenhawk1992

so i did all that put it in started right up no problem but now the batery light os on what now but no more clicking replaced the relays

ezone

Is the 4 wire connector unplugged from the alternator?
New PCM will communicate with a scanner now?


Did you fix the root cause of the failure so you don't ruin another PCM?

hildenhawk1992

so i did all that put it in started right up no problem but now the batery light os on what now but no more clicking replaced the relays

hildenhawk1992

i dont have a scanner here now im trying to find one but i think i foxed the root problem

ezone

Is the alternator 4 wire connector plugged in?
Start the engine. Unplug the alternator.
Is the battery light off now? Alternator fault.
(Edit: I don't have my notes handy but this is how I remember it...there are other control units that can keep the warning light on, but if it goes out when the alt is unplugged, the alt is causing it.)


Does the car have a Honda alternator, or a reman from a parts store?

hildenhawk1992

i unplugged the alt and the battery light stayed on and it is a factory alt i believe

ezone

Did you get the correct ECM ??? Is it any good?
Did you have the battery warning light on before you installed this ECM? Last ECM? Original ECM?
Can you plug in an old ECM to recheck with?

Do you have any fault codes? (and communication with the computer, do you have it now?)

Dash fuse box, check fuse #4 (10A) Is it blown?

Do the gauge control module self diagnostic test. Does the battery light flash during the self test?
If it does flash, gauge cluster passes test.



Unplug alternator 4 wire connector. Turn key ON.
Voltmeter: test in the black/yellow wire for battery voltage. (comes from fuse 4 checked above)

More wiring checks come after this. Checking the other wires between the ECM and alternator.