Neutral safety switch

Tiny
DANO1971
  • MEMBER
  • 1996 TOYOTA 4RUNNER
  • 3.4L
  • V6
  • 4WD
  • AUTOMATIC
  • 265,000 MILES
Okay, I am on here again with another question about the neutral safety switch. So far I switched out the neutral safety switch. That did not work! Yesterday I spent two hours cleaning out the wire harness plug that goes into neutral safety switch, checking to make sure it has power going to it and it does. My check engine light came back on this morning. I have no idea what else to do.
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Wednesday, September 13th, 2017 AT 9:09 AM

7 Replies

Tiny
CARADIODOC
  • EXPERT
First of all, what problem or symptom are you trying to solve? Have you read the diagnostic fault codes? If you did, list the code numbers.
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Wednesday, September 13th, 2017 AT 4:12 PM
Tiny
DANO1971
  • MEMBER
It is P1780 neutral safety switch malfunction. First thing I did right off the bat was put in a new neutral safety switch that was about a month-and-a-half ago. Yesterday all the wires are running from the ECU to the neutral safety switch they all lit up when I tested them went to test light. I cleaned all the terminals sprayed them electrical cleaner and scrubbed them out with a toothbrush, tooth pick and the code came up and about driving for ten miles.
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Wednesday, September 13th, 2017 AT 6:05 PM
Tiny
DANO1971
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One of the thing it only starts in park and neutral which is good. I wound up switching out the bushings underneath the shifter on the t-bar. The shift lock control switch was not catching on the shifter pin so I fixed that too. It would not go into park. Now that is fine. But for life for me I just cannot figure out what else it could be.
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Wednesday, September 13th, 2017 AT 6:16 PM
Tiny
DANO1971
  • MEMBER
Here is the bushings I switched.
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Wednesday, September 13th, 2017 AT 6:17 PM
Tiny
CARADIODOC
  • EXPERT
Dandy. When you say "all the wires lit up", does that mean you were doing continuity tests with a test light, or the wires were burning up? If that was continuity testing, that is a valid test, but only part of it. You also have to check if any two wires are shorted together or if any of them is shorted to ground. Either condition can exist even though the wires are not broken.

This code can set for a defective switch, wires shorted together, or a problem in the Engine Computer. We can eliminate the switch for now since you replaced it already. My concern now is if it took over a month for the problem to act up again, it is going to be hard to know when it is solved. To make matters worse, the service manual lists a test you can do at the computer. That involves measuring the voltage on terminal number 14 in a 12-pin plug! That is a pretty good trick.

The engine computer is behind the glove box. The wire we're after is listed as black, in plug "E8" but as I said, it only has twelve wires. Look for a black wire in one of the other plugs. With the ignition switch on,
you should find between 0 to 3 volts when in "park" or "neutral", and from 9 to 14 volts when in any other gear. If any of those are wrong, suspect a problem with the wiring.
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Wednesday, September 13th, 2017 AT 8:48 PM
Tiny
DANO1971
  • MEMBER
Thank you. I am going to try that tomorrow. When I put the new switch in it was about a month-and-a-half ago it did not take a month for it to come back on it came back on right away. It has just been a nightmare I do not always have a lot of time to work on it that is why it has been taking so long. But yeah when I change the switch out the check engine light came back on with in eight to nine miles.
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Wednesday, September 13th, 2017 AT 9:46 PM
Tiny
CARADIODOC
  • EXPERT
That is actually better than having to wait and wonder if it is solved. I hope you can find a problem with the wires. That is better than having to replace the computer. Wish the diagram was better so I could help you find that black wire.
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Thursday, September 14th, 2017 AT 1:15 AM

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