ridinny

Good day to all.. I have a 2007 Civic LX w/ ~140k on it bone stock. Everything was fine until one day I went to start it and it stalled immediately. After doing some research, i figured out that I have an immobilizer issue. I had a somewhat weak battery, so I thought the car may have lost the program for the keys.



I used a Launch X-431 Throttle to reprogram the keys, but it tells me "Immobilizer System Is Not Normal" and "D-3 No Communication Between ECM/PCM And Immobilizer Unit".



I have checked every fuse, checked all connectors at the immobilizer MICU (fuse box) and ECM. All seem normal.



I really just want to bypass the immobilizer altogether and have been looking for wiring diagrams to figure it out, but I am not 100% confident I won't mess more things up. If anyone knows how to do this, PLEASE PM me with some guidance.



Otherwise, if there is a way I can test each piece individually so I don't have to replace them all, that info would be greatly appreciated.

TIA

kevinstone2010

i have the same problem as yours, did you manage the problem?

ridinny

Unfortunately.. it's still sitting in my garage. I found another 2007 Civic LX sedan in the junkyard. I got the ECU, MICU and the immobilizer. I used my Launch x431 to reprogram then all but I still get the same error code at the end.

Crazy thing is, I periodically just try to start it even though I haven't worked on it at all... And one day it started and ran. I drove it around a little. Shut it restarted it, drove it again. Next day, the problem was back.

kevinstone2010

i have ''D-3 No Communication Between ECM/PCM'' too but i can manage that by putting unregistered key and resulting to D1 but successfully sync the immobox and ecu you can try that method

ridinny

Wow.. finally a response from someone that is actually having the same exact problem. So, I can get through the whole process right up until the end when I get D3. After that, I'm at a dead end. If I swap the immobilizer, I can start the process over until I got D3 again. Doesn't seem to matter which combination of pieces (ecu, micu, immobilizer) I have in. I've pinned out as many connections as I could figure out. I've gone through every troubleshooting step in the service manual. I've never had an automotive problem i couldn't figure out until this. I became so aggravated that it's just been sitting for 2 months.

Ryanthegreat1

Are you both using the same scan tool? Can you get your hands on an alternate tool? Or check for software updates on your tool? I have an Autel that has successfully programmed many immobilizer keys in this generation.

kevinstone2010

yes we have the same scan tool LAUNCH x431 , we have no problem with the programming keys , our problem is immobilizer doesn't communicate with the ECU.

Ryanthegreat1

Maybe a suspect MICU. That sits between the immobilizer unit and the PCM on the S-NET communication line. This is the only communication line between immobilizer and PCM.

Are you able to try another car or another scan tool? It is very possible for the scan tool to have a bug in software on this specific generation of immobilizer.

ridinny

I mentioned above that I've replaced (from same year and model car) and reprogrammed the ECM, MICU, and immobilizer. I've tried every combination of parts from both cars. If you read my post from yesterday, it comes up with D3 at the same point every time. It randomly started and ran one day even though I didn't change anything. Next day, back to the same problem.

Ryanthegreat1

MICUs were not real great around this time frame in all Hondas.

CR-V of this generation was notorious for failing MICUs.

kevinstone2010

Do you have a dump file for your MICU eeprom (93s56 eeprom inside micu fusebox) for comparing mine? my plan is to sync all the coding (ECU>MICU>IMMOBOX) so that they match altogether but i need file from other unit.

kevinstone2010

yes MICU is the problem but is the software not the hardware, starting with drain battery deletes immo coding inside the MICU and now scan tools cannot resync it, because eeprom data is corrupted and need to be replaced.

Ryanthegreat1

How did you arrive at that specific conclusion? This is an interesting topic to me.

ridinny

ok.. first off THANK YOU for the response, but I have a few questions. , 1) how do i resolve the problem? I swapped the MICU already. 2) by what you're saying, this would occur whenever a battery goes dead or is replaced, no? 3) why did the car randomly start and drive one day?

kevinstone2010

we have to find a good working MICU eeprom file and reprogram it directly to our eeprom 93c56 chip inside the MICU, did you check the battery voltage of the immobox? mine has 11volts in it but my battery voltage around 12-13volts.

Ryanthegreat1

I have two MICUs that were known good, an 06 CR-V and a 12 Civic. I could pop them open. I know that won't match your application.

Are you desoldering the eeprom to program it?

ridinny

OK.. I am not sure how to do this. which pins do I check on the immobox? Keep in mind, I have 2 of everything on hand (ECM, MICU and Immo).

kevinstone2010

yes , do you have eeprom programmer? eeprom chip inside is 93c56

tech8

This thread got very interesting.

Ryanthegreat1

I will have an eeprom programmer shortly. Looks like that 93c56 is in the soic-8 package? Any attempt to read that chip in circuit? Save some tear down steps.

Ryanthegreat1

With your scan tool have you attempted a Replace IMMO//MICU/PCM procedure? I recall seeing that on the Autel.

kevinstone2010

yes its a 93c56 soic-8 , desolder the chip, i read the chip and made a dump in it.

kevinstone2010

yes i did several times and MICU always failed! IMMObox and PCM always can sync but (D-3 no communication betwwen ECU and immobilizer) on immobilizer fault, funny thing is i can sync immobox and ecu successfully

ridinny

Hey, did this actually resolve the problem?

Ryanthegreat1

That is still a work in progress.