Here's another question regarding my 2004 GX470. Noticed my speedo was telling me I was going way too fast for what the surrounding traffic showed. When I stopped and shut the vehicle off, the gauge read 40mph:

• after driving a while, with i
• gnition first shut off, key out of ignition, and for at least 10min, gauge reads 40mph
• reading the OBD with the scan tool, speed is correct
• after sitting overnight gauge goes back to zero
• after driving from this point, gauge creeps up and stays at 40mph when at a light
• odometer seems normal
• all other gauges appear normal
• no warning lights
• no codes

So my question is:

• I have searched everywhere and can't find this symptom, anyone else ?
• any ideas?
• I see a lot of people blame the speed sensor, but doesn't reading normal from the OBD eliminate that?
• there are two speed sensors, is one for display and the other for the OBD?

You folks have been a blessing with your posts and replies, I hate to keep asking but I can use your help again. Thanks in advance.

 

If the OBD is reporting that the speed is correct, the sensor is good. More than likely there's a problem with the stepper motor in the gauge cluster.

Chip H.

 

I had something like this happen with the tachometer in 2017 and 25,000 miles ago. . Go to zero when cold and read very high after starting up. I ordered a stepper motor and was going to install it. Then got cold feet and ordeed a replacement dash module from Tanin Auto Electronix in Wisconsin. The module was perfect except the dash light for the seat belts was on when fastened and off when unfastened, opposite from what it should be. They took it back after several discussions. Had to send a video as proof. . Befuddled and recognizing that there are several different dash modules for a 2006 I didn;t know what to do. During this time I had the plastic lens off and moved the needle grabbing it by the center piece and rotated it a couple of times. Ok it moves easily. Then one day while the engine was running showing something like 2000 when it was idling I twisted the tach needle to what it should be and presto stayed there and has been good since then. It seem like once in a while you get lucky. The new stepper motor would not be that hard to solder in but I was leary of doing this since I was really not comfortable that I would get the right dash module. The dash module number is on the back. Easy to get the entire module out.

 

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