Neutral safety switch

Tiny
PCHAVERS
  • MEMBER
  • 2004 LEXUS ES 330
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 160,000 MILES
Need to know how to test because we are trying to diagnose a starting problem.
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Saturday, April 22nd, 2017 AT 9:51 AM

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Tiny
CARADIODOC
  • EXPERT
Remove the starter relay, then test for twelve volts on the terminals in the socket. A test light will be more accurate for this than a digital voltmeter.

You should find zero volts on all four terminals. Have a helper hold the ignition switch in the "crank" position. Now you should find twelve volts on two terminals. Shift to "reverse" or "drive". The twelve volts should be lost on one of those two terminals. That is the one coming from the neutral safety switch.

You can release the ignition switch. For the two remaining terminals, move the test light's ground clip to the battery's positive post. We will be checking for good ground circuits. Probe those last two terminals. The test light should light up on both of them. One is just reading through the relay's ground circuit. The other is reading through the starter solenoid, then to ground.

Up to now we do not even have to know which terminal is which. I expect you will find one of those four terminals did not read correctly. Tell me which one, and I will figure out where to go next.
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Saturday, April 22nd, 2017 AT 9:27 PM
Tiny
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My husband has tested a number of things to no avail as yet but he has ordered a new starter which will arrive on Friday so we are waiting for that. When it comes in, we can find out if it is the starter. He thinks it may be stripped out inside by the sound of it after talking to someone at an auto parts store.
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Wednesday, April 26th, 2017 AT 10:59 AM
Tiny
CARADIODOC
  • EXPERT
I have my doubts, but you didn't list any symptoms for me to analyze. The tests I described cover all four parts of the circuit with just those four readings. If they all appear to be okay, two more tests at the starter will pinpoint the cause of a failure of the starter to crank the engine. There would be two different symptoms / observations as to the clunks or other noises that are heard when turning the ignition switch to "crank".

I'll be out of town at an old car show swap meet this weekend, so don't panic if I don't get back you to see how you're doing until next Monday night.
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Wednesday, April 26th, 2017 AT 2:58 PM
Tiny
PCHAVERS
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Thanks for your help. We did follow your instructions and the neutral safety switch is fine. We received the starter that we ordered and put it in the car and now it works! So glad.

There is another issue that we are having to take care of. There is an oil leak somewhere, which my husband is trying to locate. If we need further assistance on that issue, we will contact you.

Again, thanks so much for your assistance.
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Monday, May 1st, 2017 AT 9:12 AM
Tiny
CARADIODOC
  • EXPERT
Happy to hear it's solved.

For the oil leak, if it's relatively slow, wash the area with Engine Degreaser, then add a small bottle of dark purple dye to the oil. Check a day later with a black light. The dye will show up as a bright yellow stain that you can follow back to the source. Auto parts stores will have the dye for the fluid being tested, and those that rent or borrow tools should have a black light.
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Monday, May 1st, 2017 AT 9:55 PM

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