CEL when A/C is ON

[jbbauer]

I get a Check Engine Light (CEL) only when I turn on the A/C. Hondata tech rep is telling me it's my wiring and that Hondata has nothing to do with the air conditioning. When I put the origonal ECU back (everything else constant) I do not get a CEL when I turn ON A/C. When I select Error Codes in the HondataLogger nothing is reported. So either it's the Hondata's stuff (S200 or Hondata modified P28 ECU) or its the harness... my bet is on Hondata's stuff.

BTW, not sure why the Hondata rep is saying their product has nothing to do with A/C function when I know that it controls the A/C by cutting it off whenever the car is in high boost!

Suggestions???

[Hondata]

First, please only post in one forum. I've removed the duplicate posts from the other forums.

Hondata does not alter the functionality of the CEL, so it's hard to see why the CEL would come on when you operate the A/C. What is the year & model of the vehicle, and engine? Are you using an adapter harness? When does the CEL light come on? Immediately when you switch the A/C on? Can you retrieve any codes from the ECU by jumpering the service connector in the car?

If you have RomEditor then burn a stock program (hxxx.bin) into the ECU to confirm that it is the program which you are using.

[jbbauer]

I posted in multiple forumns to expand the visability since this seems to be an exclusive issue I'm seeing.

My car is a 2000 Civic SI. I swapped my OBD2 ECU with a OBD1 ECU this require a harness adapter which I purchased from Wired Speed Lab, a Hondata dealer.

The CEL light comes on immediately when I turn on A/C. This is my first CEL in this vehicle, could you tell me where the service connector is located and which connections I'm supposed to jumper?

THANKS! I'll try a stock program bin file to verify it's not related to the my bin.



BTW I wasn't trying to imply that Hondata S200 alters the ECU's CEL functionality but the Hondata system, which in my case includes the Hondata modified P28 ECU, definately seems suspect. Because the origonal ECU is not giving me a CEL and Hondata's features include being able to disable the A/C. Just trying to get more specific info as to where to start debugging and I appreciate your feedback. The info I got from the Hondata rep on the phone was essentially it's not the Hondata, its the wiring .. that didn't help me at all.

[HESAMI]

On a 2000 Si it's the blue adapter behind your ecu. Take a small paper clip and insert both ends into the connector. Turn your ignition on and you should be able to get the CEL code. Hope this helps!

[jbbauer]

thanks, I just did this but no flashing CEL. So I guess the problem that caused the check engine light to come on doesn't translate to a problem code.

[Hondata]

Burn a stock ROM. If your ECU is a P28, then you will need to burn the 304stock.bin file into an EEPROM. You need to do this straight from the Transtronics software as RomEditor will not open 304stock.bin. The 304stock.bin file is normally located in c:\program files\romeditor\roms\stock Try the A/C. If you get a CEL, then it's the harness.

[jbbauer]

Burn a stock ROM. If your ECU is a P28, then you will need to burn the 304stock.bin file into an EEPROM. You need to do this straight from the Transtronics software as RomEditor will not open 304stock.bin. The 304stock.bin file is normally located in c:\program files\romeditor\roms\stock Try the A/C. If you get a CEL, then it's the harness.

Before I overwrite my EEPROM with a new bin, is there a way to backup the ROM currently on my EEPROM? I got this EEPROM from my dealer as a good "at altitude" base map and don't want to loose this information.

[DevineCRX]

Load the Transtronic software and use the MOVE DEVICE button. Then save the buffer.

[jbbauer]

Burn a stock ROM. If your ECU is a P28, then you will need to burn the 304stock.bin file into an EEPROM. You need to do this straight from the Transtronics software as RomEditor will not open 304stock.bin. The 304stock.bin file is normally located in c:\program files\romeditor\roms\stock Try the A/C. If you get a CEL, then it's the harness.

I was able to burn the 304stock.bin into the EEPROM for the P28 ECU which I am using for my OBD1 to OBD11 conversion. Having done this I still get a CEL everytime I turn on the A/C and the CEL goes away when I turn off the A/C. Furthermore I do not get any error codes in the "error codes" section of the HondataLogger. I also do not get the flasing CEL indicator when I jumper the blue connector. Which I assume means the CEL does not translate to an error code. Also as I origonally stated my origonal Civic SI ECU does not give me a CEL when I turn on the A/C.

The problem therefore is NOT wiring and it is NOT the "bin" ROM being used, but something in the Hondata sytem. Either the S200 or the P28 modified by Hondata. Am I the first to have this problem? What next? My first reaction is to request replacement pre-modified P28 from Hondata.

[jbbauer]

BTW thanks again for your continued help, I not trying to point fingers. Just trying to debug the issue.

[Hondata]

Can you clarify this: Using the stock rom, do you still get the check engine light with AC?

[jbbauer]

Sorry if I was not clear... Using the stock ROM I still get a CEL when using the A/C

[Hondata]

Sorry if I was not clear... Using the stock ROM I still get a CEL when using the A/C

Assuming that this is correct (there's a contridiction with one of your earlier posts) then it must either be the harness or the P28. If you know someone with a P28 (stock would work) then swap in the P28 and re-test. That will tell you if it's the harness or P28. If it's the P28, arrange for another P28 from whereever you purchased the P28. If it is not the P28, then you're going to have to trace the A/C and MIL wires from OBDI to OBDII pins, or arrange for another harness.

[jbbauer]

If it is not the P28, then you're going to have to trace the A/C and MIL wires from OBDI to OBDII pins, or arrange for another harness.

Where can I get a wiring diagram for the OBD1 to OBD11 harness?

[DaX]

I don't think they make one. You're probably going to have to get a meter and test individual wires for continuity.