I have an ignition switch problem, as far as i can tell.  This an old, 20 yr, Opel running well. Often 3 of 5 days the key turning does not start the car. All the electrical stuff turns on OK, fans etc. I can jiggle the key/switch etc and keep turning and always eventually starts. But frankly rather nerve-wracking.  Battery seems fine, once key makes contact, it powers up smartly.  I have never heard a grinding cranking sound, indicative of a week battery.

But i cannot figure out where is the problem.  And why generally first try in the morning = failure but every other time same day = start right up.

Not very interested in new switch, probably big bucks. And taking apart the ig switch will be ??

 

Might try to separate the starting wire from the other wires in the switch and make a push button starter.

Any ideas on how to test or do the button thing?

check the   solenoid  on the starter circuit 

Spray some wd in the slot and try again for a few times.

Sounds like worn out brushes on the starter to me.Or dust inside so the connection is bad.If no wires are loose, can try tapping it a bit at the same time someone turns the key.Should also hear a click turning the key.

2 hours ago, surangw said:

check the   solenoid  on the starter circuit 

Yep....had similar problem traced to solenoid.

I've had two older vehicles where the copper contacts inside the solenoid were shot.  Sometimes lightly tapping it with a hammer would allow it to work for a few days.  Learned that from my Thai BIL.

7 hours ago, donim said:

Spray some wd in the slot and try again for a few times.

All electrical systems start, so solenoid is more likely.

10 hours ago, Damrongsak said:

Sometimes lightly tapping it with a hammer would allow it to work

Spot on you can't beat the Irish screwdriver. ????

Here's my amateur/professional diagnosis.

It is the starter. Your words "And why generally first try in the morning = failure but every other time same day = start right up." 

Battery drops down a bit overnight and first start is more temperamental. But after that, rest of the day starts are easier (because a bit of charge has been put back into the battery). Starter is drawing a bit more than it should be.

UPDATE.  Took car to local shop, who know my car well. Arrived and 5 min later the electrical expert was on the job.

2 days later work done. Result: bad relay switch.  Expert said an 'off brand, japanese make' relay had been installed some years before.  My car a GM Opel.

 

He checked all other parts and they passed inspection. Total cost 750 baht.

So all told, of the 'key, switch, relay, solenoid, starter motor, battery' parts that could have been shit, at least i 'chose' the cheapest one!

 

https://www.youtube.com/watch?v=dBN86y30Ufc