I have a 1993 Honda Civic EX coupe Automatic Transmission with 180,000 miles. The car shifted out of Park fine but the IACV was making the engine idle high. I replaced the IACV with a new one then started the engine and it didn't idle high anymore but then the car wouldn't shift out of Park and the brake lights won't turn on when I pressed the brake pedal. I thought it was a coincidence that the brake switch wore out so I replaced it with a new one then reset the ECU but it still won't work. I checked the brake fluid level and it's normal. All fuses and bulbs are fine. Anyone know what the problem is? Everything was working fine until I replaced the IACV.....

Manual shift release is pointless because it's illegal to drive without brake lights working.

 

Even though you replaced the brake switch, did you replace the rubber pad that goes on switch? (You might have found little pieces that look like crayon in the foot well) I know this because it disintegrated on my clutch and the cruise stopped working and car wouldnt start period. Also you might want to check the Park/Neutral switch on your shifter (Sometimes those die). If its the pad on the pedal, its about 3 or 4 bucks from your dealer. Other wise temporary tape a penny on the hole.

 

It makes full contact. I even tested it with my fingers before installing but it still wont shift out of park or turn on the tail lights. It must be the Park/Neutral switch you are talking about.

 

Brake lights fuse under the hood is probably blown.

The circuits for the brake lights and the interlock solenoid are both protected by the fuse for the brake lights. This is not a coincidence.

 

 

Voltage test the fuse. Click link in my signature.

 

Does the horn work....? If not, check fuse 42 under the hood in the box there.

 

Yup horns work. I'm going to directly wire the tail lights to the brake switch and battery and just use the manual shift release whenever I need to use the car. This problem is starting to **** me off.

 

Do some basic diagnosing. Get a multimeter and start doing some voltage tests. Check whether battery voltage reaches the connectors for the brake lights switch, interlock solenoid, and shift lock solenoid.

Also voltage test 10A dash fuse 15.