1997 Camry w/ P0500 code

[avionicsmaster1958]

Ladies and Gents,
My Camry recently added the MIL to its display. I had the code read and it indicated a VSS failure. I changed the VSS sensor, cleaned the connector and changed the fluid along with the filter. Unfortunately the MIL is still on. I've read somewhere to disconnect the sensor and drive it around using the shifter to control the transmission. The car shifts when I select the gear and even seems to auto shift up in the higher ranges. Again, from what I've read it means it's not the transmission but with the cost of a Engine Control Module at around $500, I can't afford to get it wrong. The car has over 200,000 miles on it so it could be time for a tranny but I'd like to figure out a way to prove it could be an ECM before I go to that length.

Any ideas?

[eyeball96]

to ToyotaNation

I moved your thread to the proper forum so you may find the answer to your question.

[avionicsmaster1958]

Although it didn't come with a new gear I inspected it for missing teeth but I hadn't thought about it slipping on the shaft. The speedometer working correctly rules that out though.

The problem is the problem is somewhat intermittent and difficult to troubleshoot effectively.

Do you know if a real Toyota scan tool would have better code detection than the ones from Checker or Autozone?

[csaxon]

If speedometer works then the sensor must be OK. The signal goes from the speed sensor to the combination meter (instrument panel) to the ECM.

P0500= no vehicle speed sensor signal to ECM (2 trip detection logic)
Problem Areas:
Combination meter, Open or short in No.1 vehicle speed sensor circuit
, No.1 vehicle speed sensor,
ECM

[csaxon]

Toyota uses a more advanced scanner that has better diagnostic capabilities.

[avionicsmaster1958]

You say combination meter. Does that mean the speedo assembly?

I'm going to try the ECM next as I think I've found one in a used vehicle nearby. Do you know what range of years does the ECM fit? Most I've seen say only 1997 but the part number from AutoZ or Check don't really match what I've got.

Thanks for the bantor.

[fenixus]

I would at least make sure all plugs sitting on back of the combination meter (dash gauges cluster) are secure and tight, before replacing ECU.

best if you could check continuity on the Speed Sensor Wire between the combination meter and connector in ECU.

you must get the matching ECU, either same part number of yours or one of fully compatible part numbers (e.g. with newer firmware) and matching all components and specs like engine displacement, transmission type, california/federal emission specs, immobilizer or no immobilizer, etc.

[avionicsmaster1958]

Thanks for the info. I thought I had this fixed with no problems after driving it for two days. On the third day, unfortunately, it went out again.

I did find an ECU in a pic a part and changed it. Same issue.

After reading your reply and some other research it finally sunk in what you'd said. If the speedo is working the sensor is working. Well the speedo has never quit working so it's got to be between the speedo and the ECU. I pulled the combo meter and found the screws holding the speedo, and making electrical connections, loose on the back of the combo meter. I tightened them and it worked for two days.

While it was working I found the SPD pin on the ECU and verified I had a pulsating voltage. Most books I found say it should be either 0 and 5 volts. I'm getting 0 and 9.5 VDC. I wonder if the voltage regulator or wave shaper inside the combo meter is going out. I'm going for a combo meter tomorrow.

So far I've been able to find parts on e-bay very inexpensively. Normally a VSS would rund $150 but I found it on e-bay for $32. Found the ECU, normally $500 to $1000, for $40 at the pic a part. Unfortunately I'm no closer to fixing it. I hate intermittent problems.

[avionicsmaster1958]

Well, I hate unfinished stories so here goes. Drumroll please! It was the speedometer. I was finally able to find the right pin on the ECU and it finally failed with me watching it. Voltage stayed at 5ish volts for the duration. I put in the new, well junkyard version, and could watch the voltage change from 0 to 5 volts as the car rolled. Then it changed to a pulsating DC that I could watch the frequency increase as I increased speed.

Being an electronic geek I pulled it apart and if the schematic I have is any indication of actual circuit, it has a bad transistor. A nickel part for a $300 combo cluster. I'm going to try to fix the old one and put it back in. Why? I want the 200k miles to show up on the odometer. I'm proud of that.

Funny. The car I found in the junkyard was a 1999 with only 73k miles on it. Looks like a front end collision. I was able to get a ton of parts off of it. Luck was on my side today.

[fenixus]