2004 Trailblazer,2.4L. Tachometer not showing correct rpm. It shows about 4000 rpm when engine is off and 5000 when engine is started. Any idea where the problem could be? Thanks

It's possible that the 2004 Ford Ranger's engine or the tachometer itself is to blame for the difficulty you're describing with the tachometer reading. A crankshaft position sensor issue is one typical reason for a tachometer to read high. To determine the engine's RPM, this sensor transmits signals to the engine control module (ECM). The tachometer may show a reading higher than the real RPM if the sensor is broken.
There are several possible causes for this issue, including a problem with the tachometer itself, a problem with the sensor that sends information to the tachometer, or a problem with the vehicle's electrical system. It is also possible that the tachometer cable is loose, damaged, or disconnected.
It's recommendable to take your truck to a professional mechanic to diagnose and fix the problem. In some cases, the problem might be fixable by replacing the sensor or cable, but in other cases, it may require more extensive repairs or replacement of the tachometer itself.
It's also important to note that even though the tachometer is not working properly, it does not affect the performance of the engine, but it will give you a wrong idea of the RPM, which could lead you to over-rev the engine and cause damage.

Tow it to a transmission shop

If you can actually hear the engine race up to 5000 RPM you may have a serious problem. But more then likely you cant actually hear the engine rev up. If this is the case I would suspect a bad Tachometer ground wire.

The speedometer and tachometer problem on your Trailblazer instrument cluster is very common on the 03-06 models. It's caused by failing stepper motors on the cluster's circuit board and can be fixed. Check out this page for more on how to get it fixed - Trailblazer tachometer problems

Hello, try and turn the ignition slowly like you are going to start the engine. There is a very small "dead" space where you will see your gauge lights go off.

What you want to do is cycle the ignition switch from off to that dead space. Each time you do it your stuck speedometer will move towards zero about 10 mph. So if its stuck on 40 you will have to cycle it at least 4 times.

At first you will probably actually hit the ignition and the engine will try to start.....just release it and try it again.

Thanks

it is not a connection problem. The instrument panel will need to be replace and reprogrammed.

somebody had dash out and did not fit correctly.Have u just purchased the car?

could be a sensor problem in your catalytic convertor or air mass meter.

"The Fix" works...I would have not believed it untill I did it.... Start the car in reverse and about 5 times later it reset the speedometer back to zero.....wow!

Check EGR valve and sensor it might be carbon up or stuck and the sensor might be bad.
EGR valve and sensor connected to it control idle at start up.