How many sensor connect to the check engine light?

as to the traction/stability trac check hub and abs sensors [wires and connection ] these systems are not tied into the cam sensor but ---look for wire chaffing in the harness by the cam sensor the harness may have the wiring from both systems in harness

Traction control usually uses part of your ABS brake system to function. Sometimes a dirty (or worn out) wheel sensor is the problem that triggers both "check engine" and "traction control"...This can be verified with the proper diagnostic meter, and many shops will perform this test for free...unfortunately the free check at the auto parts stores does not include reading the ABS/Traction sensors...sensor cost is about $65. sometimes they can be cleaned. Hope this helps.

look listen and dance not matter how you performance keep it calp and trust it

Code 340 is for a problem with the cam position sensor. That would affect the tach and cause the check engine light to be on.
And most all the time the check engine light is on the other warning lights will be also. The Traction control system uses the engine and the ABS system to function. So if there is a problem with the engine, the TCS will be disabled.
The cam sensor and circuits would need to be tested. It could be a wiring problem.

probably didn't connect the tacho wire to the right side of the coil for the first problem
because the engine was replaced it is possible that a sensor wire to a wheel for the traction light was damaged /disconnected

Your vehicle is equipped with 4 of them. They are located at each of the 4 wheels. There are other reasons that the Traction Control light can come on...wheel speeds sensors are not the only reason, athough they are the most common. The traction control system works with the engine/powertrain control system and with the antilock brake system. A bad wheel speed sensor will usually also turn on the Antilock Brake (ABS) light. If the Check Engine light is also on, you could have an engine control problem causing the Trac light to come on.
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If the Trac light is on by itself, you may just have the traction control turned off. The Trac Off switch is located on the steering column.

If none of the above solves your problem, then you will have to scan your computer system to find out why the light is on. ( i.e. failed wheel speed sensor...but which one?)

Check engine light is for telling you that there is A problem with the fuel injection or emissions system, Most of the time there is no major problem to really wory about. ETS is the light for the Enhanced Traction system (traction control) This is not A vital component of your car.

If these two lights come on together then the extra traction sensor is broken and needs to be replaced when the sensor is fixed the check engine light will go off and the ets light will work properly again.

cleaning the sensor may not have fixed problem --also check connections with abs and speed sensors but recheck code and if still maf possible wiring ir sensor failure

how do I determine which oxygen sensor is bad on my 2003 forerunner ? the check engine light is on and also the vsc trac

An ABS sensor DOES affect the traction control system. Traction control uses these sensors to determine if a wheel is losing traction. A bad sensor will cause both the ABS and TRACTION lights to come on.
The CHECK ENGINE light however is going to be a seperate problem.