car will start 9 out of 10 times. You can always tell if the car isn't going to start because the green key light does not come on. If you get the green light the car starts. Replaced the ignition switch and the car was golden for 3 weeks but now it's starting again. Any ideas?

 

Just to rule out the simpler things first:

1. Have you tried with a different key? The key has a built-in transponder.

2. Have you gotten the car battery test?

3. Does the car have an aftermarket security system or remote starter?

 

Also, check the battery cables and connectors for corrosion, etc.

 

have tried the master key and the valet key does it with both. Have not tested the battery yet. When this all started I thought ignition switch so replaced it. There was an after market remote start that was still wired to the switch but was not functional. I had no idea it was there. It was removed with the old ignition switch.

 

battery used to corrode really bad so I bought the pads and new hardware and this purple stuff to stop the corrosion. that was 3 years ago and this problem started maybe 6 months ago. I will check the connections and get the battery tested.

 

Having issues with my 1999 accord. Starts every morning without fail. In the afternoons I have a 50-50 chance it will start. Sometimes the green key light will blink and other times there is no green light and the car does not start. Replaced the ignition switch and that was not the problem. Talked to some people and they said replace the immobilizer. Need some input please. Thanks

 

Your threads were merged, there is no need to start a new thread on the same issue.

As mentioned previously, have you gotten the car battery tested? I want to rule out the simpler things first before going into testing of the Immobilizer system.

 

The battery is fine

 

The issue may or may not be directly related to the Immobilizer system. Attached is a Honda service bulletin so you can understand some of the components of the system. It consists of the transponder keys, the Immobilizer receiver unit (on the steering column, next to the ignition switch) and the ECM/PCM (car’s computer). The immobilizer receiver reads the ID code from the key’s transponder and sends it to the PCM. The Immobilizer System logic is inside the ECM/PCM. When the proper ID code is sent by the immobilizer receiver, the ECM/PCM enables the fuel system so the engine will start.

Although it can be an issue with either the receiver or the ECM/PCM, the issue can also be due to something else such as either a faulty main relay, ground connection, or other unknown. You’ve already indicated the battery is fine; so, that is not mentioned here as a possible cause.

• For the ground connection, take a look at Ground G101 (located on the intake manifold plenum under the hood) to make sure the wire is good there and the connection is tight, see attached pic.

• If the main relay is intermittently not working when you try to start the car, it won’t send power (+) via a Yel/Blk wire which is necessary for the Immobilizer receiver unit to function properly. If the solder joints are faulty on the main relay, it can cause problems intermittently (like what you experience when the car is hot) or all the time. I included a picture of the location of the main relay.

• If there was a problem with the Immobilizer receiver unit, that is not too difficult to replace.

• If there was a problem with the ECM/PCM, that would require a replacement ECM/PCM and programming of the Immobilizer. Generally, without the proper testing equipment and Honda's proprietary software, diagnostic of the Immobilizer system is limited. There are other limited tests that can be done on wires though.

 

ok, thanks!