car is producing a check engine code. i read in my haynes manual that its a possible ESC module, knock sensor, or bad connection. how do i diagnose this? knock sensor is 30 bucks, but its a pain the replace. i will replace it if it needs to be, but i HATE dealing with the coolant coming out when you remove it. i also dont want to randomly replace parts either, that can get costly and is not an effective way to repair the problem.

 

Check for power and ground at the ESC module (key on, engine off). Not at home, don't have dwg's in front of me, but I want to say pink & black wires.

If you have that.... back probe the wire going to the ECM (not even going to GUESS the color! heh). Key on, engine off, watch your meter on volts (reference to ground). Take a hammer and tap the block near the sensor. Watch for voltage change. If that works... you have probably got a wiring issue between the ESC and the ECM.

If it doesn't change the voltage....don't quote me since I'm doing this all from memory, but.... I think you can probe the sensor to ground in AC volts, and when you tap the block you'll get a small voltage if your meter is fast enough to catch the pulse.

Try the above and post back - I'll check my books when I get home.

 

i think the knock sensor has failed. i have power at the pink wire, which is fed by the ignition. i also have between power on both brown wire(ecm wire i believe) and white wire(fed from knock sensor). i tapped on the front of the water pump with the engine running. no effect in voltage. i also got underneath the car and tapped on the block. knock sensor did NOT produce any voltage. i hope i have all the clear indicators that the knock sensor is the problem. i will replace it tomorrow when i have a day off. i dont mind spending the money, i just dont like spending the money and having it turn out to be something else. funny thing is that the check engine light only comes on in mid throttle. it doesnt come on at full throttle. otherwise car runs fine with no other symptoms and no noticeable knocks or pings.