Transmission shifting issues

REDCRU777

MEMBER
1998 PLYMOUTH NEON
2.0L
4 CYL
2WD
AUTOMATIC
190,000 MILES

For over a year now, every morning (after being parked overnight), when I drive this car for the first ten minutes, the low gears (1, 2) shift normally but the high speed gear suddenly slips or doesn't engage, as if it's on neutral, but if you press the gas pedal for power, the high gear engages. After it's been driven around for more than ten minutes, or when the engine or transmission had heated up, it works perfectly fine and no slipping occurs anymore through out the day.

I searched the internet for help and found some similar issues with same symptoms, and point to the VSS (vehicle speed sensor). I bought one to replace the old part, but the problem is I can't find exactly where the VSS is located in this car. I read one case in this forum and saw a diagram, but it's still not clear to me where exactly I can find the VSS but I still tried my best to look for it as per location diagram but really cant find it.

Out of frustration, I brought the car to a shop, but after diagnosing it, I was told by the mechanic that it doesn't have a VSS! I showed them the new one I bought, but the mechanic insists that this car doesn't have one. The mechanic said that the transmission oil is low and burnt and needs a flush but there might be a likelihood that the flush may even make things worst, that the transmission may completely not work at all.

This car is in very good general condition except for this transmission slipping when driven during the first 10 minutes.

Please help!

Thanks in advance to those who can advise me how to resolve this issue.

9 Replies

JACOBANDNICKOLAS

MECHANIC
108,388 POSTS

Welcome to 2CarPros.

First, it does have a speed sensor. It is located on the trans-axle extension housing. See pic 1. But, I don't think that is the problem. Honestly, if the fluid is dirty and low, that is the most likely cause.

Being low is my first suspect. When ATF gets hot, it expands. Thus, it shifts normally when warmed up. So what about his comment. "It might make it worse." If it is extremely dirty, it could. New fluid has a detergent in it and will clean the clutch plates and if they are already worn, it may slip worse. So, here is what I suggest.

Since the transmission does not slip when warm, I need you to fill the level to the full mark and see if that fixes the cold issues. If it does, then I feel somewhat confident that changing the fluid (at least the filter and part of the fluid) would help. To change the filter, the pan needs dropped and only part of the fluid will come out.

Try that first to see if filling the fluid eliminates the cold issue. Make sure to use the correct fluid type. Here is the type of fluid it takes:

Transmission Fluid Type
Type. MOPAR ATF +4 Type 9602 or Equivalent

When you check it, the engine should be at operating temperature, running, and in park. Then just check the level at the dip stick. Note: When adding fluid, use a funnel and fill it via the dip stick tube.

Let me know if you have other questions.

Joe

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Friday, June 28th, 2019 AT 7:18 PM

REDCRU777

MEMBER
81 POSTS

Hi Joe,

First of all, thank you so much for your kind and detailed reply.

At around 10 this morning, I did exactly as per your instruction, checked the fluid while the car was on idle for about 10mins, and found that the fluid isn't dirty and the level is actually a bit higher than the full (hot markhole) level. At 1pm, I went on an errand driving this car and I noticed that there was not a single occurrence of slipping.

Also, I forgot to mention that the speedometer is working but falls below 5-10 kph as compared to a couiple of street speed radar/monitors around here.

Looking forward to hearing from you.

Thanks.

Rey

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Saturday, June 29th, 2019 AT 3:36 PM

JACOBANDNICKOLAS

MECHANIC
108,388 POSTS

Welcome back:

You are very welcome. If the fluid is clean and full and your speedo isn't working correctly, I suspect the speed sensor should be replaced because it may be the cause. The powertrain control module uses the signal from the sensor to run the speedo as well as determine shift points. If you still have it, replace it and see if that eliminated the problem.

I will watch for your response.

Take care,

Joe

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Saturday, June 29th, 2019 AT 6:24 PM

REDCRU777

MEMBER
81 POSTS

Thanks for your swift reply Joe!

That's what I think so too. Yes, I have the new sensor, but the problem is I really can't locate the sensor around the trans axle. Pardon my ignorance but is it on top, in front side or rear side of the car? I can't identify its location on the image you sent and the other diagrams I found in Google.

I really wanted to replace it asap if only I can locate where it is.

Thanks for your patience.

Rey

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Saturday, June 29th, 2019 AT 7:22 PM

JACOBANDNICKOLAS

MECHANIC
108,388 POSTS

Welcome back:

No problem. It is on what is called the extension housing. The housing is mounted on the transmission right where the engine and transmission come together. If I recall correctly, if you stand at the front of the vehicle, it should be lower left where they meet. Rey, it's been awhile since I seen one. It will either be there or same side but behind the transmission. It will be roughly the same height as the top of the engine oil pan.

Let me know if you find it.

Joe

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