Vehicle Speed Sensor gear apparently not engaging

DIY-GUY

MEMBER
1994 TOYOTA CAMRY
2.2L
4 CYL
2WD
AUTOMATIC
170,000 MILES

Hi guys,

Sorry for the long question, but I wanted to be thorough.

I believe the vehicle speed sensor (VSS) is not activating. It is causing the speedometer to not work, and as a result of no speedometer signal the transmission (A140e) is not shifting out of 1st.
I tested the VSS to see if it functions by pulling it out, but keeping it hooked up to the wiring harness, and using a drill to spin it. When I did the speedometer responded in kind, nice and smooth.
I then tested to see if the transmission was turning the VSS by opening the VSS so that the top shaft could been seen if it spins and inserted the sensor back into the transmission. I lifted the car and then turned the wheel with it in neutral, and watched to see if the sensor would turn, and it looked like it almost started to turn at one point but then remained unmoved as if the teeth of the sensor gear was not connecting to the teeth of the gear inside the transmission.

I also had taken a good VSS from my wife's car (a Camry also) to see if it would function in my car and it did not, I put it back in her car and it worked fine as always for her car.

My VSS was acting up a few months ago with very erratic shifting. I did put in a new one (a very cheap one) but it made it even worse. So I took the new one's gear and placed it on the old sensor (changing just the sensor gear) and it was a little better than what I had started with, but it was still erratic. I had been driving with that until the other day when it was a first cold day of the season (I live in Arizona, so cold is a relative thing, maybe sixty degrees or even fifty degrees at night) and the transmission would not shift up very well.
My transmission has had problems over the last six years or so with not working if it was cold and would take about a mile of driving to warm up and start shifting normally. However, this time with the VSS not really working, seems that it has really bit the dust.

I had hoped that a change of fluid and filter would help, but it did not.

Also the only codes I got was 42, which is the VSS.

If the gear really is not connecting what would cause that, and how can I fix it? Does it require the transmission to be pulled (which on this car is a very large job from my research) or can this be fixed on the vehicle? Or have I missed something?

The uploaded image is just an example I found online of what my VSS looks like.

I would be truly grateful for any help you can give me.

Image (Click to make bigger)

3 Replies

KHLOW2008

MECHANIC
41,815 POSTS

Hi DIY-GUY,

This component is known to fail regularly. Referring to the picture that you posted, at the right is the fiber gear. Different models might have different number of teeth and the diameter could be different so it could work on one vehicle but not the next. You need to confirm if both have the same number of driven tooth (with the one that you borrowed from your wife's vehicle). If both are the same, did you try using the unit from your vehicle on your wife's vehicle?
Did you check for abnormal wear of the fiber teeth? The fiber gears do get damaged at times.

This component can also be erratic in the sense that it can work well for a while and then fails intermittently.

If the VSS is tested to be good, that would be a major problem. The driving gear inside the trans-axle cannot be repaired/replaced without stripping apart the transmission.

The transmission control unit depends on the VSS to understand the vehicle speed and provide the gear shift changing command so with a bad VSS, the shifting would definitely be erratic.

Unable to shift when cold is usually due to a fault with the valve body controls (the shift solenoids are not working smoothly/efficiently). This could be due to aged shift solenoids, lower than normal battery voltage, transmission fluid quality or high resistance in the wiring circuit.

Have you ever checked for trouble codes with the transmission controls?

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Tuesday, December 12th, 2017 AT 8:23 AM

DIY-GUY

MEMBER
2 POSTS

Hi KHLO2008,

Thanks for replying to my question.

The only error code I got from checking the OBD1 was a 42, which was the VSS.

Per your suggestion I tested my VSS on my wife's car and it worked perfect. It looks like it might be the driving gear inside the transmission, would you not agree?

You mentioned the solenoids, could one of them not working cause the driving gear to not engage or some how have caused the current problem?

This is probably a stupid question, but can the gear be accessed while still on the car, I think the answer is probably not.

What might be your recommendation at this point,

1. replace the Solenoids, can they be cleaned or refurbished?

2. get a rebuild kit and rebuild the transmission,
https://www.ebay.com/i/221852187253?chn=ps
or https://www.ebay.com/i/282239669478?chn=ps

3. Buy a used transmission

4. Buy a rebuilt or re-manufactured transmission - which is better?

5. Buy a new car.

The attached image is from a video I found online that shows the same speed sensor and cover removed from the A140E transmission.

Thanks for any feedback,

DIY-GUY

Image (Click to make bigger)

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Wednesday, December 13th, 2017 AT 2:23 PM

KHLOW2008

MECHANIC
41,815 POSTS

Sorry for the delay in replying.

The test indicates the VSS is not at fault and one more thing you need to check is the VSS wiring circuit. If there is any fault with the wiring circuit then it has to be rectified before the VSS would work. You need to test for power supply to the VSS connector and also continuity to the TCM.

Buying a new car is always the best option as you would be free of trouble for a few years but is that a viable option?

Yes, the picture shows the correct thing and if you can get the cover removed, you might be able to see what is wrong. Too bad I don't think it can be done om vehicle meaning you need to remove the transmission from vehicle to work on. At the point where the fiber gear of the VSS is, the driving gear is located there.

If the VSS fails, it would result in erratic shifting and this should be rectified first before we go on to solving solenoid problems if any. Solenoids can be replaced and can be purchased separately. Refurbishing is not possible.

A used transmission is not the best option if you are think of repairs/replacement. A rebuilt one would be better.

Getting a rebuilt kit is good if you are able to perform the repairs but transmission repairs are not for DIY as certain areas such as disassembling/assembling clutch pack seals requires special tools or technique to accomplish.

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Friday, December 15th, 2017 AT 7:37 AM