03 Matrix engine light - ABS ECM failure

[matrixdriver]

My 2003 Matrix 4cyl AWD - engine light on. Speedomoter and all panel instruments are working. No symptoms drives fine, brakes fine.

I took it in for engine code diagnostic and emission test for state inspection. I am told that code P0500 accounts for the engine light (they say that I must replace the ABS Electronic Control Unit/Module, $1561 plus labor).
I am told that the error code cannot be cleared since it recurs each time the car is started. Because the code is present the State inspection equipment refuses to run the emission test.

Questions- Am I being taken for a ride? Is there really no way to clear this code besides replacing ABS ECM? Are there cheaper aftermarket ABS ECM's available or where might be a source for one?

[toyomoho]

P0500 is the speed sensor.

Is check engine or ABS light on?

[roadrunner2]

Matrixdriver,
That's a pretty big leap (Guess) from reading a code to instant diagnosis.

Was any testing performed on any part of the ABS system? There are speed sensors on each wheel.

I would prefer you take your vehicle to someone else for a second (and maybe even a third) opinion before allowing this repair.

DO NOT tell the next shop what the previous one said, let them check for themselves.

[mikered30]

Possible causes for the code, vehicle speed sensor A:

Instrument cluster malfunction
Open or short in vehicle speed sensor circuit
Vehicle speed sensor
ECM

Does your speedometer read correctly all the time, even in reverse? I know you said it works, but can you verify that with radar or GPS? ABS work like it should?

Can you take it to autozone or advanced auto to get to code checked for free to see if the shop was telling the truth?

I would go to another shop for a second opinion. Since they appeared to have lied about the part being bad, try disconnecting the negative battery terminal for an hour. The only thing you could lose is your radio stations. See if the CEL comes back after 100 miles of driving and then take it to a different shop for inspection.

[matrixdriver]

Thanks for the advice. To answer some questions.

No the ABS light has not been on. But the engine light was on. The shop says they reset all error codes and that the P0500 returns each time the car is started. I think the only reason that they began testing the ABS system was a result of the P0500 codes. I pressed them for more details and codes and they said they followed the diagnostic flowchart and it pointed to the ABS ECM.

I now have the car back (did not buy a new ABS ECM) and will follow advice given here...

I have not yet tested the ABS performance, I am not sure the best way to test it but will do some hard braking to see what happens.

I have only casually observed the speedometer and not noticed any problem. At your suggestion I will test it with a GPS and watch it during backing up.

After doing an autozone test I will remove the battery terminal, wait and retest.

I will post my observations.

[mikered30]

Originally Posted by matrixdriver

Thanks for the advice. To answer some questions.

No the ABS light has not been on. But the engine light was on. The shop says they reset all error codes and that the P0500 returns each time the car is started. I think the only reason that they began testing the ABS system was a result of the P0500 codes. I pressed them for more details and codes and they said they followed the diagnostic flowchart and it pointed to the ABS ECM.

I now have the car back (did not buy a new ABS ECM) and will follow advice given here...

I have not yet tested the ABS performance, I am not sure the best way to test it but will do some hard braking to see what happens.

I have only casually observed the speedometer and not noticed any problem. At your suggestion I will test it with a GPS and watch it during backing up.

After doing an autozone test I will remove the battery terminal, wait and retest.

I will post my observations.

Did they say what the other codes were? You can test ABS on any wet/icy back road or going down a hill on a back county road with no one around. I don't know if you ever had your ABS kick in, but it pulses the pedal and makes a vibrating noise, that is normal. After you disconnect your battery terminal, press the on the brake and turn on the lights, that will help discharge the ECU faster, but still wait 1 hr before connecting again. Let us know if the light comes back on, it may not be right away

[matrixdriver]

I appreciate the advice that helped me avoid the service that was advised. I did not let the dealership change the computer.

Per advice in posts- I verified that the speedometer is working in both forward and reverse. I disconnected the battery for 1 hour then reconnected it and drove to Autozone for a diagnostic test. The check engine light came on while I drove approx 3 miles to the store. The Autozone test produced code P0400 - which I was told is the catalytic converter error. I recently replaced the Catalytic converter... maybe the new one is faulty? I will now run down some answers about it and then hopefully get the emission test done that started this goose chase.

[larry9h]

It sounds like I'm having a similar problem. I just inherited an 03 Matrix XR-S and took it to get it's state inspection, it failed, check engine light was coming on. The inspection shop said that the code indicated a speed sensor was out. I took it to an honest mechanic that I've dealt with for many years and he agreed with the code diagnosis but when he replaced the speed sensors, the check engine light would come on again after he drove it for a few miles. The next move apparently is the ABS system. We've been waiting for almost two months for the part from Toyota. He's already told me that if it's this part that is bad it's going to be around 1800 for the part alone. I was wondering if this is a problem that many Matrix drivers have had. It's a nice little car and want to get it fixed so that I can get it inspected and drive it! Does it sound like I'm going down the right path?

[fishexpo101]

If its a P0500 CEL - Vehicle Speed Sensor Malfunction, then it only has to do with the vehicle speed sensor installed in the transaxle. The speed sensors for the ABS are part of their own independant system. If swapping the sensors didn't fix it and the wiring is good (most likely failure is in the harness itself) - then the ECM is suspected next. An ABS warning is a completely different story - it will flash its own warning lamp