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Pigtail on passenger side by transmission

Tiny
JEEP769
  • MEMBER
  • 1999 JEEP GRAND CHEROKEE
  • 4.7L
  • V8
  • 4WD
  • AUTOMATIC
  • 190,000 MILES
Okay, I recently discovered a hole in my transmission on the passenger side. It is right up by the exhaust with the exhaust coming through to the back of the vehicle. So, it's hard to see but I did get a picture of it there is a circuit board it looks like on the inside of it. I am wondering what is supposed to be plugged into here and there's also a pigtail harness just dangling there since about the vehicle, and I've always wondered what that was to plug into, and I am guessing that is where it's supposed to be plugged into, I just don't know what it plugs into. Any information would be great, and my vehicle has been running very rough lately my output speed sensor is running a code and so is my O2 sensor because I have that unplugged. I don't know if this photo will help but this is on the passenger side of transmission.
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Saturday, May 21st, 2022 AT 11:08 AM

15 Replies

Tiny
STEVE W.
  • MECHANIC
  • 13,462 POSTS
That is what is left of the output speed sensor. The bolt next to it comes out and the sensor gets removed and replaced with a new one, Spray around it with some brake cleaner to remove the crud then spray on some penetrant. Be gentle while removing it you want to get the entire thing out and the O-Ring on it tends to stick and you can break it inside the transmission. Then plug the wire back into it and the error code should go away.
Then reconnect the O2 sensor as that is likely the cause of the rough running and left disconnected can destroy the converter as well as cause a lot of extra wear in the engine due to it running rich.
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Saturday, May 21st, 2022 AT 1:44 PM
Tiny
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There are no catalytic converters or muffler on it also. That is because the people before me cut them out. I was almost positive that the part that's missing was the neutral safety sensor. Also, on the passenger side of jeep on the frame is a braided ground cable that is cut and I'm not sure where it went. It's on the frame under the passenger front door between the exhaust pipe and rocker panel. Any idea where it went or if this will cause any problem to the way it runs?
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Sunday, May 29th, 2022 AT 2:39 AM
Tiny
STEVE W.
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Well, the missing parts would be why it runs rough. They use the signals from the sensors in front and behind the converters to control the fuel mix. With them missing it's probably running in some version of open loop and that isn't intended for good operation, more of a limp mode.
The speed sensor missing also doesn't help. As for it being the neutral switch, nope that is all a part of the shifter's position sensor that tells the PCM what gear you are in, no other neutral sensor on it that has actual circuitry.
Braided ground sounds like a chassis ground but not in that location.
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Sunday, May 29th, 2022 AT 11:13 AM
Tiny
JEEP769
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Okay, thank you for your help with the speed sensor I am working on getting that fixed. And as for the braided wire or cable ground it is right by my transfer case right where the hole is on my transfer case, or the speed sensor goes. It is on the other side of my exhaust bolted to the frame. Didn't know if that would cause it to run rough also.
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Sunday, June 5th, 2022 AT 9:43 AM
Tiny
STEVE W.
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Well, as a general rule modern Chrysler vehicles tend to have poor grounding systems where they will take multiple grounds and combine them in one connector and the internal wires corrode and cause problems but on the exterior, they look perfect. As for the braid, service info doesn't show it, but I would expect it to be a chassis ground from body to the transfer case or similar.
Could you take a picture of it and post it, it might make it easier to see where it went.
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Sunday, June 5th, 2022 AT 10:00 AM
Tiny
JEEP769
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Here is the braided ground cable I am seeing on the passenger side by the transfer case.
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Thursday, June 16th, 2022 AT 11:35 PM
Tiny
STEVE W.
  • MECHANIC
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Don't see a braided cable. I see what looks like wire loom which is likely for the sensor that is missing in the middle. Once you replace the speed sensor and plug it in see if that code goes away.
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Friday, June 17th, 2022 AT 12:25 AM
Tiny
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Okay, well, got the sensor and took out the old. The sensor doesn't fit into the harness that is unplugged. The harness on the Jeep has four holes to plug into it and the speed sensor only two prongs. I am not so sure if this is a transmission speed sensor that broke off. I'll send you a picture of what is left of it after we had taken it out of the right side of the transfer case.
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Sunday, June 19th, 2022 AT 12:57 AM
Tiny
STEVE W.
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Okay, that looks like the pressure transducer, should be three wires from the plug. Mopar part 4799758AF
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Sunday, June 19th, 2022 AT 1:19 AM
Tiny
JEEP769
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Yes, I found it on this webpage:
https://cardiagn.com/jeep-parts-list-1999-wj/

My scanner is reading a code for the output speed sensor so got that part and just need to put on and then the pressure sensor will be next when I get paid. Thanks for all of your help!
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Monday, June 20th, 2022 AT 9:48 PM
Tiny
STEVE W.
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If you are looking for parts and want to buy, online take a look at rock auto. The output speed sensor is on the opposite side from the pressure transducer. That will be the part you already have.
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Tuesday, June 21st, 2022 AT 5:01 AM
Tiny
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Yes, it was the part that I've got and the code reader had that on there. Why isn't the transducer pressure sensor reading a code?
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Saturday, June 25th, 2022 AT 10:39 AM
Tiny
STEVE W.
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It might be setting one but some scan tools have issues reading Chrysler TCM codes.
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Saturday, June 25th, 2022 AT 11:33 AM
Tiny
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Okay, thanks for all your help. Now I've got a caliper in the right rear that the guide pins are shot and wore my brake pads uneven and grooved out my rotor. If it's not one thing it's another, haha. Have a Happy 4th!
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Monday, July 4th, 2022 AT 9:17 AM
Tiny
STEVE W.
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Yeah, the joys of vehicle ownership never end. Happy 4th to you as well.
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Monday, July 4th, 2022 AT 10:10 AM

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