The reason why I say experts only is because I havent had one person here who can correctly diagnose the issue.
Lexus Es300, 94, 143k miles. Cel codes p0500 and p0720 I was having issues with my od light flashing and cel with my car. High rpms and hesitation. Replaced one speed sensor on the tranny to the advice of a mechanic. No improvement.
Lexus Dealer said get another ecu and dash cluster.I recently had my old ecu remanufactured. And I got a used dash cluster. The cel and od light came back on after a few hours. Tried resetting the ecu did not help. Same problems.
Do I need to get the other (output) speed sensor replaced?
This cold be an ecm problem so here is the proper way to check to see if it is or notat least for the speed sensor. Diagnosis & Repair
1. Check speedometer operation. If speedometer is operating properly, go to next step. If speedometer is not operating properly, check for open or short in VSS circuit. See SYSTEM/COMPONENT TESTS
article. Repair as necessary.
2. Access ECM behind glove box. Turn ignition off. Disconnect ECM E10 connector. See Fig. 6 . Using DVOM, check for continuity between ground and terminal No. 12 (Violet/Yellow wire) at ECM E10
connector. If continuity does not exist, go to next step. If continuity exists, locate and repair short to ground in Violet/Yellow wire between ECM and instrument cluster.
3. Measure voltage between ground and terminal No. 12 (Violet/Yellow wire) at ECM E10 connector. If voltage is 9 14 volts, go to next step. If voltage is not 9 14 volts, locate and repair open in Violet/Yellow
wire between junction block No. 3, located behind instrument cluster, and ECM.
4. Check for open in Violet/Yellow wire between junction block No. 3 and instrument cluster. See appropriate wiring diagram in WIRING DIAGRAMS article. Repair wiring as necessary. If wiring is okay, then replace ecu.
Make sure to check the ground for the ecu it is a white/black wire on left side of manifold, make sure it is NOT corroded or dirty. You might have a trasn guy look at this as you may have an internal trans problem as well. But keep in mind any type of engine problem will effect the trans. You other sensor is for O/D it h as a th/blu an dyel/blu wire leading to it. You might try to see what resistance the o/d sensor is giving. Test a new one at an autoparts store then see what yours is. If it's within range then suspect a overdrive clutch problem. The 720 code may be a clutch/seal problem as well
April, 16, 2012 AT 6:36 PM
Ok, are there any other tests for an output sensor problem? I know soemtimes my tachometere is going much faster than my speedometer.
April, 16, 2012 AT 7:03 PM
The tach going faster than speedo is normal. You needto increase yoru rpms as yu get up to speed. BUT, if your tach is giing faster than it normally did say like 30, 00 miles ago i'd reccomend you going to a trans guy as you probably have a failing clutch/seal in trans. If your fluid is brownish or dark in color that is a good tipoff.
April, 16, 2012 AT 7:38 PM
What if the tach stay s up at the same pace of the speedometer after I stopped speeding up and I am holding at say 60mph at 3000 rpms? Seems too high
April, 16, 2012 AT 7:45 PM
Like I said if it used to be say 1800 at60 and now is 3000, it's probably not in o/d and the clutch pak or seal is burnt up. That is why your light is probably flashing. Take to a trans guy andlet him look at it. He can tell you better than I can
April, 17, 2012 AT 2:10 PM
Im just going to drive it till it breaks down then im going to get rid of it. At this point the money I would have to put into it.A 1995 its not even worth it. Guess I got one of the bad ones. Lol. Thanks for the help.