Where are the speed sensors on a 2004 chevy trailblazer?

First you need to have EBCM - electronic brake control module check for DTC'S - diagnostic trouble code's . If the light is on there is a code stored . I think most part stores can do this and for free . After you find out what code is stored , looking up that code in service repair information for diagnostic trouble shooting chart would be next step . There are a few codes too.
DTC C0035 or C0040
DTC C0045 or C0050
DTC C0110
DTC C0131
DTC C0161
DTC C0186
DTC C0196
DTC C0201
DTC C0240
DTC C0241 or P0856
DTC C0244 or P1689
DTC C0245
DTC C0283
DTC C0287
DTC C0290 or C0292
DTC C0455
DTC C0550
DTC C0558

Find the code do the diagnostic's , fix the problem , wiring issue's , a sensor , bad module ,what ever it is . The light will go out then . Here is a sample of code discription .
• DTC C0035 Left Front Wheel Speed Sensor Circuit
• DTC C0040 Right Front Wheel Speed Sensor Circuit

code p0014 - Chevy TrailBlazer, TrailBlazer SS and GMC Envoy Forum

forums.trailvoy.com > ... > OEM Issues

Sep 8, 2007 - 11 posts - ‎8 authors
On my Trailblazer I have a code P0014 . this says Camshaft Position Actuator B ... If the desired and actual cam phase angle error exceeds its ... This diagnostic procedure supports the following DTC: ... replace the camshaft actuator solenoid, change the engine oil and filter, ... 2004 Chevy TrailBlazer LT P0014 - Camshaft Position Actuator Solenoid "Relearn"
11 posts
Dec 11, 2009
cam crank sensor mismatch
11 posts
Jul 4, 2009
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Tech Code "dtc P0014" 2003 Trailblazer - Chevy S-10/Blazer ...

www.gm-trucks.com/.../72278-tech-code-dtc-p0014-2003-trailblazer/

Dec 31, 2007 - 14 posts - ‎6 authors
Tech Code "dtc P0014" 2003 Trailblazer - posted in Chevy ... it had been serviced before for the same thing in 2003 or 2004! ... replace the camshaft actuator solenoid, change the engine oil and .... The extended war. co. prob. would not be to happy since they already fixed the sensor once or twice already.

Replace a Camshaft Position Actuator Solenoid Valve on a ...

? 8:05
https://www.youtube.com/watch?v=4Dkdd287AKg

check cruise control fuse and check the brake lights see if brake light working because the brake light switch will deactivate cruise control when brakes is applied.if brake lights dont work either fuse blowed or switch bad.if all is good have vechicle code scan because cruise control control by PCM and vechicle speed sensor and thottle actuator control motor.

could be a sensor...have it scanned...sounds like the problem....and good luck.

it could be a plug wire that is loose on the plug or a plug that may not be firing right due to dirt(carbon) shorting the plug not letting it fire.you can check to make sure the wire is on the plug tightly and pull the plug and check the plug gap and condition of the plug.

I had the exact same problem on my 2003 Trailblazer. The check engine light came on, I took my vehicle to autozone and they told me the code was P0495 (cooling fan speed high)but they did't know how to fix the problem.
I called the dealer and they told me that it would cost me $89.00 to reprogram my PCM. I took my vehicle to the dealer and now my trailblazer is working like new. I hope it's that simple, the other thing also that could have gone bad would be the relay to your electric fan. The relay is a not like a normal relay but is more like a module that can regulate the speed of the electric fan which a tech2 scanner can determine if it's bad or not. Good luck
Thank you for using fixya.

Just disconnect the battery (negative terminal) and turn the headlight switch on for about 15 minutes. This should reset the PCM. Otherwise go to Advance and have them hookup the code reader and reset the codes. Thanks

I don't see many bad sensors I would co to an auto zone read code if its a vss ck connevtors & wires at sensor does the trns shift if not ck the purpple & green wires

I suppose the engine code said that cylinder was not firing or faulty? I would immediately get a compression check done on the engine. It is relatively painless. My burnt valves (compression 10psi vs 150psi) could not be diagnosed any other way. Does this help?

the check engine? you need to have it scanned and the codes cleared at an autoshop. it will just pop back on if the problem isnt taken care of.