Intermittent no crank unless bang under key ignition on dash

‘07 Hyundai entourage. At times it won’t crank unless you hit under the key ignition on the lower dash. We’ve made all repairs as diagnosed. 1st was told, starter. 2nd some waterproofing around crank sensor. Sensor not replaced but some sealant was added. Most recently starter relay. Is crank sensor under hood or any ideas where to look. Tech doesn’t believe it’s a ignition cylinder.

You need a better “tech”. The reason I say this is the starter replacement; the first “go to” for mechanics that can’t properly diagnose problem.

Just from your description, I would guess it is the ignition switch.

(sadly…another perfectly good starter is replaced)

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I’m going to second Mustangman. Ignition switch. So many incompetent mechanics now-a-days.

I agree this is the ignition switch. Several cars ago I had a similar intermittent no start. Jiggling the key and banging got it to start, my mechanic (a pretty good guy) insisted it was the starter. After he replaced the starter it still was a problem. He then replaced the key/ignition switch and sheepishly showed me a frayed wire.

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There’s also the possibility the problem could be related to the neutral safety switch. Maybe that dash banging is just enough to cause that switch to operate. Next time it acts up gently shift into neutral and see what happens.

I’m also in agreement that you have been the victim of some bad guesses. The starter motor and sealing the crank sensor is way down the list with the latter being “unorthodox” to put it kindly.

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Sigh… and another perfectly good starter is replaced…

I am going to have some Tee shirts made up… “Save the Starters - It is Something ELSE!”

I’ve owned 26 cars or so in my life with mileage from 20 to 147K and I may have had ONE bad starter… but its been so long ago I can’t remember which car it was.

something else to check…

07-90-009 Hyundai Technical Service Bulletin (tsbsearch.com)

Despite it’s moniker, the crank sensor – aka crank position sensor – is unrelated to cranking the engine. That part is used to tell the computer what position the crankshaft is in. A faulty crank sensor won’t prevent the engine from cranking.

When you turn key to "start’ and don’t here anything at all, common causes are

  • battery faulty or discharged
  • battery connections loose or corroded
  • ignition switch faulty
  • clutch or transmission safety switch faulty
  • ignition relay faulty (very uncommon)
  • starter motor faulty

When this symptom happens to me, first step, I measure the voltage at the starter’s “s” terminal (thinner of the two wires) with key in “start”. Should be at least 10.5 volts.