Speedometer crazy and transmission shifting crazy and slipping - sometimes

Asked by Sep 27, 2016 at 08:17 AM about the 2002 Toyota Camry LE

Question type: Maintenance & Repair

330,000 miles.  When cruising on the highway, the trans will sometimes
downshift crazy and the speedometer sometimes goes to zero.  Some days I
have not problems at all.  Usually happens when its warm on the highway but
after it starts, it'll happen an slow speeds.  After a day of rest, its typically OK
- for a while.
Replaced BOTH speed sensors on the transmission
Replaced the instrument cluster.   
Getting ready to solder the leads to the speed sensors to eliminate the plugs
as a source.  

Anybody have any other ideas?

23 Answers

222,415

at 330K miles and the original transmission, I'd say your overdue for a rebuild. Consider it a good thing, you got your money worth out of it.

1,020

If this Tranny is Computer Controlled....I would road test this vehicle with a Scan Tool in place checking inputs and outputs. Have you noticed any warning lights ON or Flashing? What does the Tranny Fluid look/smell like?

I have had it scanned several times but not wile driving. The diagnostics at AutoZone always indicate: "Vehicle Speed Sensor Circuit Malfunction". That is why I replaced both VSS sensors. I replaced the transmission filter an fluid after the problem started. It was way, way, way over- due. It was dark. I cleaned the ground contacts on the ECM, including the contacts on the board itself. I could not quite figure out what fuse/link supplies power to the VSS's - (let me know if you do know). I pushed down hard on all the fuses/links in the engine box and dash box. Surprisingly, most of the links (not fuses) were NOT 100% seated and went down just a hair. Hmmmm.... After 14 years and 330,000 miles perhaps they start to loosen up a bit.. Drove the car > 100 miles today with no issues - so far. We shall see.

1,020

Ok...good History. This may be a wiring problem between the VSS's and the Computer. Now we need a DVOM(Digital Volt Ohm Meter) and a wiring diagram. The Code ID(letter and number) would ID which sensor/circuit is faulty....the DVOM will tell us if a signal is reaching the Computer The wiring diagram will tell us which wires/colors to check at the back of the computer to test. So...having said all that....WHO is going to run these tests. The signal being sent by a good VSS is usually AC Voltage...thus...we need to know a little about Auto Electricity to complete the diagnosis. Not knowing your background in this area...you might consider a good repair facility. Keep us up to date on this interesting issue.

1 out of 1 people think this is helpful.

I began the process of attempting to find where the circuit goes for the 2 VSS units. It is hard to find good information. What I did do was to push down on all the fuses/circuit breakers in the engine and dash fuse panels. I was surprised to find that most of the breakers/links where NOT FULLY SEATED. I guess after 14 years the vibration backs them out - just a hair. Not much. But I wonder.... anyway, its been about a week and hundreds of miles without a significant problem. Could it be???

1,020

With the technology used on these cars......I would not be surprised if you may have "fully seated" and solved the problem....however...if/when the problem resurfaces...I would suggest an immediate stop to where ever you have Computer Codes Scanned. Write down the ID of any Codes to include the Alpa/numeric ID, Get back to us for further analysis.

The code is "Vehicle Speed Sensor Circuit Malfunction" - seems obvious - but - The problem is recurred but is very sporadic. I might go for days without a problem then it'll crop up for about 5 minutes - then go away. I checked the connectors to both VSS units again and they are firm. I wish I knew where those wires went so that I could check them all along their path....

970

The VSS Sensor...is it a 2 wire sensor or a 3 wire sensor. What colors are the wires?

It was 2 wires - I would have to remove the air box again to get the colors. What do you think?

970

Time to regroup and clarify. When I go online and search for a VSS for a 2002 Camry....I see a 3 Wire sensor for Automatic Trans. I see a 2 wire Sensor for a Standard trans. So...What Tranny is in this vehicle....and....are both of these VSS located in the Transmission. Can you take a picture of both Old sensors and post?

970

UPDATE....This is what I have found......you will need a voltmeter to check for an AC voltage at the ECM. D connector. (L)...means BLUE. Front wheels must be turning.

970

Hope this helps

1 out of 1 people think this is helpful.
Best Answer
970

Another interesting note. Seems there is a Toyota Service Bulletin that addresses this issue. TBS-0072-10. Code P0500. Does that code ring any bells?

Yes - I'm pretty sure that is the code. I don't find anything when I google that TSB number - can you send a link to it?

Thanks for that diagram! Where did you find that? Based on it, the two sensors go directly to the ECM - surprise to me! each are 2 wire in the diagram. If I get desperate - I can run new wires to the 2 VSS units :)

I will look more closely at those wires when I next get a chance - thanks!

970

Here is another thought I just had. 2wire speed senors are usually magnetic reluctor types. They have a coil of wire rapped around a magnet. If the end of the sensor picks up a lot of dirt and Metal Particles....it effects the operation of the sensor. If you still have those old sensors....it might help if I could see a picture of said sensors.

970

Oooops...a small typo error above. That Service Bulletin # is TSB-0072-10.

I replaced both sensors last summer - they were clean. The local Toyota dealer wants $125/hr to "look" at the car when all I want is and updated ECM. Do you know a mail-order solution for that?

970

I assume an "updated ECM" ,...really means Re-flashing the ECM that is in the vehicle. That process is usually performed by a Toyota Dealership. It would be a lot cheaper to invest in a DVOM from Wal-Mart and make an attempt to check the wiring from the sensor to the computer...and...the signal coming from the sensors to the computer.

970

gc...so what's new concerning this vehicle?

970

Just had another thought. Does the Odometer(Mileage) function work properly on your Cluster assembly? is your Speedo still going nuts?

1,020

gcapilot.....so what's new concerning this vehicle?

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