Problems With The Speedometer - Corolland: the Toyota Corolla Forums

I just bought my 99 corolla this summer. Everything was going fine until one day the check engine light came on and the speedometer dropped to 0. I took it to a mechanic and had the speed senser replaced, but once again the light has come on and the speedometer dropped to 0. It will stay off for a while, then it starts to work randomly until the car is shut off for a while. It seems to only happen when driving on the highway and using cruise control for a while. I took it to auto zone and the computer that they plugged into the car read: speed sensor malfuction and fuel exaust malfuction. I already had the speed sesor replaced, does anyone know what else could be causing this problem?

The mechanic should have asked - why did the speed sensor fail in the first place. Chances are - the original speed sensor was fine, you probably have an intermittent connection somewhere between the speed sensor and the ECU. Could be a bad wire or possible a bad connection at the sensor or on the ECU side. Other possiblities are poor chassis grounds, bad ECU, or a short somewhere in the cluster itself. Did Autozone give your the exact CEL codes the last time around? Would be very helpful to know the exact code and the order they were stored in memory.

alright, the autozone codes say

DTC (Codes)

P0441

EVAP Emission

Control System

Purge Flow Fault

P0500

Veh Speed Sensor A

Malfuction

DTC Pending (Codes)

po441

EVAP Emission

Control System

Purge Flow Fault

P0446

EVAP Emission

Control System

Vent Circuit Malf

I think that maybe all the emission codes are on there because when the speedometer failed the transmission wasn't sure what gear it should be in so it missed and caused all these errors, but I could be wrong.

p0441 and p0446 are evap. codes, usually caused by improperly tightened and/or missing gas cap.

as for the speed sensor issue, has the speedo head been out? if so, pull it back out and check to see if the conectors were properly plugged in. your mechanic should have verified it needed a speed sensor first.

aaron

Bikeman982

Jason86 you listed P0441 twice.

I posted that code twice because thats how everything was listed on the autozone paper. I bought a new gas cap to try to get ride of those codes, they came back. On top of all that my gas mileage is down to 22 mpg around town, and I tried fuel injector treatment, checked the air pressure in my tires, checked my air filter, and just had my oil changed a while ago. But atleast the speedometer only stops working on the highway. I don't know whats up with my car. If anyone has any clues to whats going on or any ideas, or what I could do, it would be very appreciated.

How do you fill the gas tank - do you run it to the first click/auto shut off and stop or do you top it off. If you do the latter - stop - this is a sure fire way to saturate the vapor canister and possible clog up the two valves right next to the canister. A very expensive piece.

Give these two codes together:

P0441 - EVAP emission Control System Purge Flow Fault

P0446 - EVAP emission Control System Vent Circuit Malf

You have a high porbably that you have an EVAP issue somewhere. Dealers are quick to jump on the vapor canister or charcoal canister as the culprit and will replace it to the tune of $300 + labor (can be the culprit in the end, especially if you top off the tank - but try and explore other avenues first before dumoing some serious cash into this - you can do some diagnostic work and find out for yourself if that is the case.)

Take a peek at my Photobucket site (click the link in my sig or the link posted here) - I have scanned pages that include an overview of the EVAP system, specific components, and some diagnostics steps that you can take to check each part. If you want to take a stab at this yourself - you can save a truckload of money and get a better understanding of the EVAP system on the Corolla (a personal sore point for me as well as other 8th gen owners).

https://smg.photobucket.com/albums/v620/fis.../EVAP%20system/

Unusual to have the fuel economy go down as well - if it was a very drastic change (dropped from the usual 28MPG to 18MPG for example) then it could be multiple issues. Could also be an ECU "feature" - as the computer is very sensitive to chassis ground (having GOOD grounds). If any new pieces of electronics have be introduced (new headunit, amp(s), ICE, new wiring anywhere, etc. - could be funky grounds. I personally found that that the ECU seemed to be very picky at first - improved greatly when I replaced the OEM battery with a better unit and re-did the chassis ground points for my audio system. Now the headlights don't dim anymore - when I turn on extra accessories.

Bikeman982

I posted that code twice because thats how everything was listed on the autozone paper. I bought a new gas cap to try to get ride of those codes, they came back. On top of all that my gas mileage is down to 22 mpg around town, and I tried fuel injector treatment, checked the air pressure in my tires, checked my air filter, and just had my oil changed a while ago. But atleast the speedometer only stops working on the highway. I don't know whats up with my car. If anyone has any clues to whats going on or any ideas, or what I could do, it would be very appreciated.

Does it only malfunction when you put the cruise control on?

Unusual to have the fuel economy go down as well - if it was a very drastic change (dropped from the usual 28MPG to 18MPG for example) then it could be multiple issues. Could also be an ECU "feature" - as the computer is very sensitive to chassis ground (having GOOD grounds). If any new pieces of electronics have be introduced (new headunit, amp(s), ICE, new wiring anywhere, etc. - could be funky grounds. I personally found that that the ECU seemed to be very picky at first - improved greatly when I replaced the OEM battery with a better unit and re-did the chassis ground points for my audio system. Now the headlights don't dim anymore - when I turn on extra accessories.

I called a bunch of toyota dealers, and they all gave me different asnwers on what the problem could be, one said the ECU, one said something about the wire cluster might be shorted, and the other said it is probably cruise control. Since you said that an ECU problem could make MPG's go down and the dealer said that could be shutting off my speedometer, maybe that's it.

The dealers said they could look at it, but it would probably cost a lot. Next time I am on the highway for a while I'm not going to use cruise and see if the speedometer goes off, so I can try to eliminate that as one of the problems because everytime it went off cruise was on. They said the only thing I could do is bring it in and hope it messes up when they drive it so they could figure out what is wrong. But it probably wouldn't mess up when I wanted it to. I'm hoping the 22 mpg is related to the speedometer problem, but who knows. I never top off my tank so I'm hoping thats not the problem. Thanks for all your imput, if anyone knows anything about this or has any other ideas, or simular problems let me know.

Bikeman982

Unusual to have the fuel economy go down as well - if it was a very drastic change (dropped from the usual 28MPG to 18MPG for example) then it could be multiple issues. Could also be an ECU "feature" - as the computer is very sensitive to chassis ground (having GOOD grounds). If any new pieces of electronics have be introduced (new headunit, amp(s), ICE, new wiring anywhere, etc. - could be funky grounds. I personally found that that the ECU seemed to be very picky at first - improved greatly when I replaced the OEM battery with a better unit and re-did the chassis ground points for my audio system. Now the headlights don't dim anymore - when I turn on extra accessories.
I called a bunch of toyota dealers, and they all gave me different asnwers on what the problem could be, one said the ECU, one said something about the wire cluster might be shorted, and the other said it is probably cruise control. Since you said that an ECU problem could make MPG's go down and the dealer said that could be shutting off my speedometer, maybe that's it.
The dealers said they could look at it, but it would probably cost a lot. Next time I am on the highway for a while I'm not going to use cruise and see if the speedometer goes off, so I can try to eliminate that as one of the problems because everytime it went off cruise was on. They said the only thing I could do is bring it in and hope it messes up when they drive it so they could figure out what is wrong. But it probably wouldn't mess up when I wanted it to. I'm hoping the 22 mpg is related to the speedometer problem, but who knows. I never top off my tank so I'm hoping thats not the problem. Thanks for all your imput, if anyone knows anything about this or has any other ideas, or simular problems let me know.

That sounds like a good plan to test whether or not it is tied into the cruise control.

Dealers always want you to bring it in, and they do cost a lot.

I have not heard that an ECU can shut off the speedometer.

i just got to thinking about this. i will try to remember and look when im at work tomorrow, but is there a adapter between the speed sensor and the tranny? some toyota's use a little "key" between the two. if so, it might be worn out and easily overlooked. hard to explain what i am talking about, but i will try to look at a picture tomorrow.

aaron

Bikeman982

I just bought my 99 corolla this summer. Everything was going fine until one day the check engine light came on and the speedometer dropped to 0. I took it to a mechanic and had the speed senser replaced, but once again the light has come on and the speedometer dropped to 0. It will stay off for a while, then it starts to work randomly until the car is shut off for a while. It seems to only happen when driving on the highway and using cruise control for a while. I took it to auto zone and the computer that they plugged into the car read: speed sensor malfuction and fuel exaust malfuction. I already had the speed sesor replaced, does anyone know what else could be causing this problem?

Sounds like an intermittent wiring problem - check the connections and also meter the wires.

i just got to thinking about this. i will try to remember and look when im at work tomorrow, but is there a adapter between the speed sensor and the tranny? some toyota's use a little "key" between the two. if so, it might be worn out and easily overlooked. hard to explain what i am talking about, but i will try to look at a picture tomorrow.aaron

ok, looked at a mpicture and the 99 corolla doesnt use one of those "keys". so, my memory left me again....

aaron

Bikeman982

I just bought my 99 corolla this summer. Everything was going fine until one day the check engine light came on and the speedometer dropped to 0. I took it to a mechanic and had the speed senser replaced, but once again the light has come on and the speedometer dropped to 0. It will stay off for a while, then it starts to work randomly until the car is shut off for a while. It seems to only happen when driving on the highway and using cruise control for a while. I took it to auto zone and the computer that they plugged into the car read: speed sensor malfuction and fuel exaust malfuction. I already had the speed sesor replaced, does anyone know what else could be causing this problem?
Sounds like an intermittent wiring problem - check the connections and also meter the wires.

If you have changed the speed sensor already and the speedometer is good, chances are it is a wiring problem (usually a pin in a connector that is loose).

I haven't had the speedometer stop working on me for a while, but I haven't had to do a lot of highway driving so it is only a matter of time before it does. The gas milage around town is terrible, Do you think the P0441 and the P0446 codes could come up for a bad oxygen senor? and could that be my problem with the gas milage, and possibly my speedometer? Or do you think they are completly unrelated problems?

Bikeman982

I haven't had the speedometer stop working on me for a while, but I haven't had to do a lot of highway driving so it is only a matter of time before it does. The gas milage around town is terrible, Do you think the P0441 and the P0446 codes could come up for a bad oxygen senor? and could that be my problem with the gas milage, and possibly my speedometer? Or do you think they are completly unrelated problems?

The sensor could be dirty, giving fault codes and poor fuel efficiency.

Try cleaning it off first and see if anything changes.