Toyota Camry -- Speedometer not working... Will it fail smog?
in [Toyota]
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From: Rav on 13 Nov 2009 06:21 The "check engine" light came on 03 Toyota Camry. The mechanic checked with the diagnostic scanner and confirmed that it was because the speedometer and odometer were not working. He checked some other stuff which I didn't understand -- something to do with vehicle sensors. He said he suspected the car computer and that he would need to read the manual to see if he can fix the computer but I may have to take it to a dealer for expensive repair or replacement of the computer. Also, the mechanic mentioned that the car would not pass California Smog with a non-functional speedomoter/odomoter. Is that true? Not sure why smog check would care.
From: Scott Dorsey on 13 Nov 2009 08:50 Rav <raul.fremont(a)gmail.com> wrote: > >The "check engine" light came on 03 Toyota Camry. > >The mechanic checked with the diagnostic scanner and confirmed that it >was because the speedometer and odometer were not working. How long have they not been working? >He checked some other stuff which I didn't understand -- something to >do with vehicle sensors. There's a sensor in the transmission that tells the instrument panel how fast the transmission is turning. Sometimes that sensor breaks. >He said he suspected the car computer and that he would need to read >the manual to see if he can fix the computer but I may have to take it >to a dealer for expensive repair or replacement of the computer. It could also be a cabling issue somewhere. >Also, the mechanic mentioned that the car would not pass California >Smog with a non-functional speedomoter/odomoter. > >Is that true? Not sure why smog check would care. Because without the odometer running, they can't query the computer to get accurate engine information. If they want to know how much gas you're using per mile, for instance, they need to know how many miles you have gone. --scott -- "C'est un Nagra. C'est suisse, et tres, tres precis."
From: Ray O on 13 Nov 2009 12:31 "Rav" <raul.fremont(a)gmail.com> wrote in message news:4246b30b-ada5-4977-8cfc-ee9c8761c79a(a)j9g2000prh.googlegroups.com... > > The "check engine" light came on 03 Toyota Camry. > > The mechanic checked with the diagnostic scanner and confirmed that it > was because the speedometer and odometer were not working. > > He checked some other stuff which I didn't understand -- something to > do with vehicle sensors. > > He said he suspected the car computer and that he would need to read > the manual to see if he can fix the computer but I may have to take it > to a dealer for expensive repair or replacement of the computer. > > Also, the mechanic mentioned that the car would not pass California > Smog with a non-functional speedomoter/odomoter. > > Is that true? Not sure why smog check would care. It is unlikely that the car's engine control computer, referred to as an electronic control unit, or ECU, needs repair or replacement because they have a very low failure rate. A competent technician who is familiar with Toyotas knows that the engine ECU is the last thing to check, not the first thing to check. Even if the engine ECU did need repair, it would have to be sent out to an authorized repair facility for repair. The reason that the car would not pass smog is that vehicles with the check engine light (actually called the malfunction indicator light, or MIL) illuminated automatically fail, and the reason that the MIL is on is because of a problem with the speed sensor circuit. There is a speed sensor on the transmission that sends a signal to the speedometer control on the back of the instrument cluster, and diagnosis is pretty straightforward. The On-board Diagnostics Generation II (OBD II) scan tools used by professional technicians should have the ability to read the signal generated by the transmission speed sensor and therefore check the function of the speed sensor. Even if the technician's scan tool does not have this capability, the sensor can be checked with a volt meter at the sensor itself. If the sensor is putting out the proper signal, then the next step would be to check the wiring between the speed sensor and the speedometer control by checking the signal at the wire harness at the speedometer control. If the signal is good, then the speedometer control is bad, and if the signal is bad, then the wiring between the sensor and speedometer control is bad. The most time consuming part of doing all these checks would be removing the instrument cluster to get at the speedometer control, about a half-hour total for all the checks. If anyone did any work just before the speedometer started acting up or if you had any electrical work done on the car like installing an aftermarket remote starter or audio system, I'd check that work first to make sure that the speedometer circuit wasn't disturbed. -- Ray O (correct punctuation to reply)
From: AZ Nomad on 13 Nov 2009 12:54 On Fri, 13 Nov 2009 03:21:26 -0800 (PST), Rav <raul.fremont(a)gmail.com> wrote: >The "check engine" light came on 03 Toyota Camry. >The mechanic checked with the diagnostic scanner and confirmed that it >was because the speedometer and odometer were not working. >He checked some other stuff which I didn't understand -- something to >do with vehicle sensors. >He said he suspected the car computer and that he would need to read >the manual to see if he can fix the computer but I may have to take it >to a dealer for expensive repair or replacement of the computer. >Also, the mechanic mentioned that the car would not pass California >Smog with a non-functional speedomoter/odomoter. >Is that true? Not sure why smog check would care. the engine computer gets the road speed from the speedometer, actually there's a cable or switch on the transmission that both the speedometer and engine computer use.
From: Jeff Strickland on 14 Nov 2009 13:12 "Rav" <raul.fremont(a)gmail.com> wrote in message news:4246b30b-ada5-4977-8cfc-ee9c8761c79a(a)j9g2000prh.googlegroups.com... > > The "check engine" light came on 03 Toyota Camry. > > The mechanic checked with the diagnostic scanner and confirmed that it > was because the speedometer and odometer were not working. > > He checked some other stuff which I didn't understand -- something to > do with vehicle sensors. > > He said he suspected the car computer and that he would need to read > the manual to see if he can fix the computer but I may have to take it > to a dealer for expensive repair or replacement of the computer. > > Also, the mechanic mentioned that the car would not pass California > Smog with a non-functional speedomoter/odomoter. > > Is that true? Not sure why smog check would care. Yes, it's true. The Smog Nazis will fail the car if the Check light is on for any reason. The computer uses speed data to make decisions on how much gas to use, and stuff like that. The decisions affect how many pollutants are spewed from the tail pipe. If the speed data is missing, the decisions will by definition be wrong, and the pollutants will be high, even if they are not high in actuality. The Check light is ON, so the decisions must be wrong. Period. You could get the bright (no pun intended) idea to unplug the Check light, but that will cause you to fail smog too because a requirement of the smog check is that you be properly notified that the decision making process has gone astray. The check includes looking to see if the light comes on when the ignition is ON, then goes out after the engine starts. The failure modes for the smog test are, Check light never on and always on. Of course, if the light happens to come on, go off, then come on during the running ot the test, that's a failure opprotunity too. As for your problem, I recall reading that the speed sensor on the tail shaft of the transmission has some kind of problem. Perhaps RayO has discussed this, or will discuss it.
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