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Old 10-03-2019, 11:58 PM
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Angry Ignition Switch Not Getting Power

Hey Jeep owners, so I’m completely stumped! Literally one day out of the clear blue sky, my Jeep stopped starting. Nothing outta the ordinary happened, just one morning it wouldn’t start. The ignition switch is not getting any power.

I checked everything possible, even replaced some fuses just in case, and still nothing! I gave the it12 volts directly you the wire, and it started right up without a hitch. But otherwise, the switch is getting no power.

No clue why it stopped getting power all of a sudden. Literally nothing happened, it just stopped! Anyone have ANY clues as to what it might be??

Battery is good, fuses are good, wire and wire harness connections are all goochie...

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Old 10-04-2019, 07:58 AM   #2
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Play with the shift lever a little and see if that works. Shift to neutral and back to park several times

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Old 10-04-2019, 09:03 AM   #3
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The ignition switch receives power from fuse M27. Should be a 10A fuse. You say the fuse is good but have you tested it with it in place? It's a mini fuse and should have little metal contacts exposed on the top of fuse that allow you to test it. Grab a test light, clamp it to battery negative. Then touch each side of the fuse leg...though those exposed holes on the top. Does the test light light on each side? If it does, then you have an issue from the right side of the fuse to the ignition switch. Could be wire, could even be part of the TIPM. If it lights on one side but not the other it's a bad fuse. If it doesn't light at all then something is not right in the TIPM (assuming the TIPM is getting power).
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Old 10-04-2019, 09:05 AM   #4
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Quote:
Originally Posted by Bob Sanders View Post
Play with the shift lever a little and see if that works. Shift to neutral and back to park several times
This. Put it in neutral and see if it starts... if it is, neutral safety starter switch is your issue. The switch isnt recognizing the gear is in park so not allowing it to kick over.

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Old 10-04-2019, 09:32 AM   #5
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Originally Posted by daveray9 View Post
This. Put it in neutral and see if it starts... if it is, neutral safety starter switch is your issue. The switch isnt recognizing the gear is in park so not allowing it to kick over.

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The Neutral safety switch is not in the circuit the OP is describing therefore messing with the shifter won't change anything. If he provides power to the ignition switch the Jeep starts when the key is turned to start. The neutral safety switch is on a different circuit tied to the PCM.
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Old 10-04-2019, 11:00 AM   #6
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Can bus systems sense key position via resistance at key switch
The resistance is sensed but the WIN which then sends out a can bus signal

It is not a power connection switch


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Old 10-04-2019, 11:35 AM   #7
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Can bus systems sense key position via resistance at key switch
The resistance is sensed but the WIN which then sends out a can bus signal

It is not a power connection switch


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A few things are at play with the JK ignition switch. The ignition switch does require battery postive that is provided by the TIPM. When you switch to run or start, 12v gets sent to the WCM (wireless control module) and to the TIPM. There is another wire that comes from the ignition switch into WCM. This wire actually will contain different voltages depending on what position the key is in. The service manual has a table of these. From here the WCM translates that to the key position and sends a message on the CAN bus. The TIPM then looks for that message to be in start and the 12v on the first wire. Then it will tell the PCM to do a start. The PCM then looks for all the conditions to start, including neutral safety switch and initiates a start.
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Old 10-04-2019, 11:38 AM
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Quote:
Originally Posted by Bob Sanders View Post
Play with the shift lever a little and see if that works. Shift to neutral and back to park several times
Quote:
Originally Posted by daveray9 View Post
This. Put it in neutral and see if it starts... if it is, neutral safety starter switch is your issue. The switch isnt recognizing the gear is in park so not allowing it to kick over.

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I wish it were that easy, but unfortunately that is not the case.

Quote:
Originally Posted by sequel View Post
The ignition switch receives power from fuse M27. Should be a 10A fuse. You say the fuse is good but have you tested it with it in place? It's a mini fuse and should have little metal contacts exposed on the top of fuse that allow you to test it. Grab a test light, clamp it to battery negative. Then touch each side of the fuse leg...though those exposed holes on the top. Does the test light light on each side? If it does, then you have an issue from the right side of the fuse to the ignition switch. Could be wire, could even be part of the TIPM. If it lights on one side but not the other it's a bad fuse. If it doesn't light at all then something is not right in the TIPM (assuming the TIPM is getting power).
I actually did not look at the M27, and only changed the J17. I'm not a car whiz or anything, just know a little bit and Google the rest, and that is what everyone seemed to say to attack first.

M27 though, thanks for the tip! Will look into it.
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Old 10-04-2019, 10:48 PM
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Talking

Problem solved!! It was in face the 10amp M27 fuse that was the culprit. Swapped it out with a new fuse, and started right up without needing to be tapped into another power source!

Thanks for the tips and advice fellas...
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