Vehicle: 2008 Honda Civic Si

Crank + Start: Yes

Battery: new and charged

Alternator: New (problem occurred before new alternator and persists after)

PROBLEM: Brought my car in for the airbag recall, left the dealership fine.

Next day A/C and radio won’t function. Blower works but no A/C. Driving to the dealership radio turns on, still no A/C. Dealership says A/C relay blew. Doesn’t check anything with radio. A/C functions normally and radio is working.

Next day, oem car alarm goes off when ignition is placed to on position and continues with vehicle running. Changed alternator suspecting Low voltage from battery not turning off security system. Pull horn fuse and let car run for 1 hour. Turn off car, insert horn fuse, lock door, unlock door from outside get in and start car. No more alarm but still no stereo. Turn off car. Notice rpm gauge stuck at 1000rpm and no beeping telling me my keys are in ignition with door open. Turn key to ACC position, no power to anything except interior lights. Start car to make sure it cranks and get electrical power, car starts fine and everything is energized minus the stereo. Turn off key and take it out. Interior lights work but power locks don’t. Turn key all the way on but don’t start, everything is energized except stereo, power locks work in this position. Turn key back to ACC, immediate loss of all power except interior lights and security system flashing.

I’m at a loss. I’ve checked all fuses and checked wiring the best I can. All fuses including main bat fuse shows cont from terminals.

EDIT Just happen to hit the flashers accidentally and with flashers on, no key, the doors will lock and unlock and the headlights/high beams will work. No beeping from key in ignition and started the car and shut it off leaving the flashers on and rpm gauge still stops at 1-2000 rpm as if the power was killed. As soon as I turn off the flashers door locks won’t work and headlights don’t turn on.

  • Welcome to Motor Vehicle Maintenance & Repair! While I wouldn't know for sure, this sounds like a problem with your body control module (or whatever Honda calls them). The BCM controls all power for the items you've mentioned and seems like it might be a commonality. Commented Jun 28, 2020 at 17:06
  • 2
    Try bridging pins 4 and 5 in your OBD2 connector with a paper clip see if symptoms improve. There is a common grounding issue's on these cars and this will temporarily fix it. If that does nothing then @Pᴀᴜʟsᴛᴇʀ2 may be on to something. The bcm does control many of the things listed including parts around the airbag being replaced. They may have shorted something and damaged the bcm. This is all just speculation so make sure you do solid testing first since replacing it requires some reprogramming in the immobilizer chain.
    – narkeleptk
    Commented Jun 28, 2020 at 22:47


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