Car won't turn over - is it key problem

Having same problem over last month since I bought the car. It won’t turn over at all, but there is plenty of juice. Every once in awhile it will start after about 20 attempts. It will start a few days without issue.

Have replaced the solenoid, and the starter twice. Electically it reads good but that is only after it starts to take it to the garage so they are not reading it when it doesn’t work.

The key sometimes catches. The fob is so old that it doesn’t work and is missing buttons.

I was reading somewhere that the key for this car has a transponder, but I don’t know that for sure.

Guesses on it being a key issue? I’d hate to spend 200 on new key if it is not. So far I am at nearly 300 on this starting issue and it is not fixed.

Also, any cheaper ways to get a transponder key that works?

Thanks!

I don’t know: would the key keep it from turning over, or would it keep the fuel pump from running, or the ignition system from firing a spark - or some combination of these?

Another possible factor is the neutral safety switch (usually on the clutch pedal mount), or the park-neutral switch somewhere in the automatic transmission or its shift linkage. These prevent the starter from running when the car is in gear.

Not sure what year Neon you have but, according to the 2005 Neon owners manual (the last year), if your key is bad or you have an unauthorized key, the immobilizer system will allow the engine to start and then shut off after 2 seconds. When the key is in the “on”, do you have power?

I presume this is an intermittant “fails to crank” problem. Ask your shop to measure the voltage at both terminals on the starter motor during attempted cranking. Terminal to starter case. Both should measure at least 10.5 volts. If one of them measures below 10.5 volts, work backwards towards the battery to find out why. If both measure over 10.5 volts and it doesn’t crank, that’s almost always a faulty starter motor. If it never fails to crank at the shop, ask if they can install two volt meters in your car’s passenger compartment temporarily, attached with wires to the test points above. Then when it doesn’t crank, you’ll be able to report what the voltages were. If not that, then you’ll have to leave it with the shop and use another form of transport until they can get it to fail. One of the staff there could drive it back and forth from their home to work.

It’s a 2002. I have tried moving the car into neutral and/or back again and various combinations to ensure the car was registering in a gear that would allow it to start…

I can say it doesn’t turn over at all. But when the key is in the “on” I have good power to everything… Unfortunately I have not yet checked the security light which would match a key error like I started to suspect because I just started to suspect it today. And since it’s in the mood to start recently it probably wouldn’t say much until it refuses to start again…

I haven’t turned up any info on what a key issue would do - whether it would start for 2 seconds or something else.

Having said all that, if you or anyone else has a clue before I go spending again, I would really appreciate it…

Thanks for answering!

fyi, that doesn’t imply the battery is necessarily good. Cranking requires more than 100 amps and really stresses the battery and connections, while everything else electrical you’d power-up with the key in “on” but engine not running doesn’t stress the battery nearly as much.

Thanks. I guess I should have added that I have had certified AAA battery techs test the battery more than once to ensure it is fine… It has been through 2 techs and 3 mechanics now… I can say the problem is elusive which is one reason the transponder in the key is suspected, but I am really open to anyone suggesting otherwise so no more time and money is wasted.

The first thing I’d be looking at is the brake light switch and the transmission interlock switch. If either of those fail, the car thinks it’s not safe to start and you won’t get any cranking. Brake light switch is an easy test- have someone see if the brake lights are coming on when you step on the brakes as the car isn’t starting.

Assuming that’s working, try shifting to neutral and then starting the car. Does that work consistently? Then the interlock isn’t properly detecting when you’re in park.

Inspect the crimps on the battery cable clamps, I have replaced battery cables on these cars because the cable crimps become loose. This problem is illusive, it is usually difficult to replicate and generally results in replacing the battery, starter and alternator without solving the problem.

Try to push/pull on each cable, if there is any movement the crimp is loose. If moving the cables allows the engine to start there is a problem with the cables.