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Discussion Starter #1
i recently bought a used IS300 (blue title). and my speedometer does not work. all the other gauges (gas, odometer, tachometer ect..) work fine. i talked to my local mechanic, and he said that maybe my speed sensor wire might my loose or dirty (maybe from flood damage). honestly i dont even know where to begin to look. my mechanic told me its near the transmisson under the car. i told him that i thought lexus is all electrical and stuff. but he still told me to take a look under my car. i jacked up my car and removed some of the undercover. i saw some wires and stuff but i dont know which one to take out and clean. can anybody please help me!!! :whine:
 

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For stuff like that your best bet is to take it to lexus, or buy yourself the shop manuals. They can be worth their weight in gold at times.
 

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Take it to the dealer. Also, did your speedometer work when you first got it? Also, what is blue title? Does that mean salvaged? Usually when the speed sensor is not hooked up or broken, the odometer no longer functions. that is how it works for most hondas. I'm wondering if it is the same for lexus also.
 

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Your Odometer is working and the speedometer is not??? :-? :-? :-?
That means the speed sensor is hooked up.

Do a search in mobiltronics for the speed sensor wire that goes into the trac ecu, so you can use a voltmeter to see if the speed sensor is hooked up (drive 10MPH and Check the volt reading).
There are also wiring diagrams available for download from go-fast forum.

I have a feeling your gauge cluster might be the cause of the problems (if the odometer is really working, i.e. incrementing miles as you drive)

I recommend to go through all electronic components and check that the connectors are plugged in all the way. Disconnect the battery's negative terminal first and remove then plug back all of the connectors. Do that for the ECU under the hood and for the Trac ECU above the pedals. Repeat the same procedure for the Gauge Cluster.
 

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Discussion Starter #5
i am sorry if i was not clear..but my odometer turn on with the no. of miles on the car but does not increse. if i use a voltmeter, how do i go about using it. i am sorry for the confusing, and thanks for all of your help everybody..all of you go out of yalls way to help everybody!! :D
 

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You would set your Voltmeter for 20V max, stick black(negative) terminal into the ground (car's metal body) and connect the positve to the wire you're taking the reading from.

If you're not proficient in electric, do not do this yourself. The repair cost will only increase once you start breaking things.

As I stated previosly, try replacing all of the connectors. One might be loose.

You can also get a GPS unit and get your speed reading from there. I usually check mine for speed, since the speedometer is only 97% accurate.
 
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