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Dodge Repair/'02 Neon: Automatic: self shifts gears in rain


QUESTION: Hi Roland,
I have a 2002 Dodge Neon with automatic transmisson. When on the highway and in the rain, it shifts between the two high gears. You can feel it shift either up or down and the engine RPM changes 400-500 RPM accordingly. This does not happen normally....only when it's raining. It also does not seem to happen at lower speeds. Only at highway speed shifting between high gears. Clearly something is getting wet and an electronic signal is being sent to the wrong destination or at the wrong time. I took the car to a Dodge dealer and they believe the transmission range sensor is missing it's cover. They do not have that part to replace it, however, and say that Dodge no longer makes it.  I have tried to find a schematic showing that part but can't find it. Are you familiar with this part, and if so, does it make sense that that would be the problem? Was that cover meant to be waterproof to keep water out of the Trans range sensor? If you agree that that could very well be the problem, do you have any idea where I might find one (just the cover)



ANSWER: Hi Bill,
The range sensor proper is located inside the transmission, so I don't see that there is any "cover" for it. However the gray plug (8 wires/10 pins) for the electrical wiring of it is external and located on the side which faces the front of the vehicle directly next to the vertical shift rod which is connected to the shifter in the cabin. So you could take a look at the plug and associated wiring harness to see whether there might be a bare wire(s) that are touching each other or the body of the transaxle and thus causing an electrical short circuit.
For diagnosis of what might be wrong you would want to get a fault code readout using a plug-in code reader which attaches to a socket under the dash near the steering column. A nationwide auto parts store (e.g. Autozone) might do it for free or an independent shop will charge around $40 for the readout. Get the fault code number(s), and what they mean, what is suggested to be done. Then send me a follow-up question with the details and we'll compare notes with the service manual. The trans is a 40TE model in that vehicle.
I can tell you the connections for the 8 wires and you could test them between both ends for a short/open condition using a continuity tester or an ohmmeter.
Please read the PS (below) and respond to it.

---------- FOLLOW-UP ----------

QUESTION: Okay, so I talked to the tech that looked at the car. He said that the service writer mis-spoke to me. The tech thinks the issue is that a "skin-like cover" is missing from the transmission control module (not the transmission range sensor) that covers the module and where the wiring harness goes into it. I tried to look at schematics on line and I see nothing of the sort? I talked to a parts person at Dodge and she said that her schematic showed a cover but it was included with the wiring harness, not the module, and that the wiring harness was big and included a lot of different ends going different places (read, you don't want to replace it.) They did not mention a code showing a fault. The car does NOT have this issue when driving conditions are dry, only when it's raining, so I'm thinking there is not a problem with bare or chaffed wires touching ground (or each other)...if that were the case I would think it would do it all the time, right? So it's only doing it when it's wet.....meaning to me something is getting wet and shorting or water is allowing current to pass from wire to wire (like maybe in a cannon plug, or where wires are connected.) The tech said he put dilectric grease in the cannon plug (I'm assuming the one that goes into the control module) hoping that would prevent any moisture there. I have not got the car back yet, and will obviously have to drive it in the rain to see if it happens again. I was also thinking of putting a gob of silicone over that cannon plug when I get it home. Your thoughts? Do you see any type of cover in your available literature?
Thank you so much for your time.


ANSWER: Hi Bill,
The powertrain/transmission controller is a single unit with 4 plugs. The 4th plug (green) is primarily for the transmission so focus on that one first. The controller is located on the left side of the engine compartment, forward. I don't recall seeing anything about shields for the individual plugs, so you may just want to cover it yourself. Also cover the plug for the trs on the transmission.
Thanks for the rating and nomination which you are welcome to do both once again (a limit of 5 such nominations per month for an individual volunteer by a single questioner).

---------- FOLLOW-UP ----------

QUESTION: Do you have a picture or schematic that you can send or publish showing the transmission controller? I don't think you are talking about the shift module as that is down below on the front of the transmission. Is the transmission controller up on the inner fender somewhere? And when you say "cover them yourself". what do you mean? Was that in response to my silicone thought or do you have another idea?

Thank you.  Bill

Yes, Bill, tell me your email address and I can send a figure that shows the location of the powertrain/trans control module. I can't recommend a specific cover substance, I was thinking rather of some plastic bag/sheet material. When you tell me the address don't use the @ symbol, instead use "at" or the address will be erased automatically.

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Roland Finston


Get a Free Fast answer to your repair question about a Chrysler/Dodge/Plymouth car, minivan, SUV, or truck. Problems with electronically controlled engines and transmissions as well as body wiring problems are my specialty. This free troubleshoot advice forum helps you diagnose faults, minimize repair costs or do-it-yourself.

I answer questions seven days a week and respond to you in about 30 minutes. "Maxed Out" means I am answering another question or briefly unavailable so try again later.

I have do-it-yourself experience (50+ years) and a library of 100 1982-2012 Chrysler factory shop manuals and 20 multi-manual Chrysler Corp. CD's.

I was voted "Top expert" from 2010-2015 here at AllExperts, and have answered 20,000+ questions.


Five decades as a 'do-it-yourselfer' on domestic and imported cars

Yahoo Autos Group called The Chrysler Lebaron Club (co-moderator)

Degrees in Physics/bruised knuckles.

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"Top expert" of 2010, 2011, 2012, 2013, 2014, and 2015 here at Allexperts. Quickest "average response time" at Allexperts (currently no. 1).

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