Rep Power: 0

I have a 2005 Honda civic 4 door with a automatic dash harness matched with a 2003 civic ecu/ecm with existing automatic harness. All mounted to a d17a1 with a manual trans, engine starts runs decent other then iacv is sticking however a snap on scan tool is unable to connect to the ecu. As well as I have a permanent battery light but all grounds seem good as well as the alternator ground has been re done. Engine will rev all the way to 7000rpm so not sure the issue. Really need some help!!! Tia

 
Rep Power: 222

Seems like you're missing a ground, or got a wire crossed. You did check the fuse for the obd connector and all the related fuses?

 
Rep Power: 229

You have the radiator mount to head ground wire connected right?

then theres the alternator wiring and the ground from battery which splits to the transmission and body.

 
Rep Power: 0

it has a good ground to the head and battery is grounded good and gets 14.7volts when running. Belts are nice and tight as well. But I did cut 2 wires under the dash from one of the fuse box connectors I think it was plug 2 plugs down and the second one in from the right. I cut pin 7 and 11 and grounded them someone told me I had to so it would trick it into thinking it was in nutral and will rev. Other then that I'm lost. I might try to run my auto ECU with matching ignition ALSO the auto harness that is on the manual engine and trans isn't connected to the ac the speed sensor any of the auto trans sensors. Don't know if that would do anything or not. The car seems to run fine other then stalls sometimes when cold

 
Rep Power: 0

I have no idea about the wire cutting hack but 04-05 Civic uses wideband upstream O2 sensor so technically, it's not compatible with a 03 ECU.

 
Rep Power: 0

I have a 03 engine with matching exhaust manifold so it has 03 o2 sensors

 
Rep Power: 224

Usually when we see a scan tool that won't connect to the ECU it's due to a loose alternator mounting bolt.

 
Rep Power: 0

I have installed a new alternator as well as the mounting bolts however I didn't clean off the surfaces that the alternator ground would be touching. Do you think it will fix my battery light if I take off the alternator and clean all the grounding surfaces?

 
Rep Power: 222

Possibly, need to make sure the bolts are tight as well, however it may be too late and you've fried the ecu

 
Rep Power: 0

Do you think its fried even tho I haven't driven it like that and it revs fine when sitting there. Cuz I have blown one a while back in my old civic from a loose alternator and it revved all weird

 
Rep Power: 224

There's only one way to find out. Remove the alternator, clean the mounting surfaces, reinstall ensuring all bolts are tight (top alternator bolt, alternator to bracket bolt, alternator bracket to block).

 
Rep Power: 0

Cleaned it all re installed and still has a battery light. What do you guys think is I just run it with a battery light on because the whole car runs fine

 
Rep Power: 134

Where and what kind of alternator did you replace it with? Possible faulty replacement alt?

 
Rep Power: 0

Car quest and its about a year old I ran it for a bit on my other engine