Toyota Repair: 1988 Toyota 4Runner, toyota 4runner, knock sensor

Question
I have an 88 toyota 4runner 4cyl. that is giving me #52(knock sensor) code due to check engine light coming on.The light does not come on when engine is started.It only comes on while driving at different speeds.Anyhow is there a way to check if the knock sensor is bad before replacing?

Answer
The repair manual list three possible cuses for this trouble code:
An open wire between the knk sensor and the ECM
A malfunctioning KNK sensor
A malfunctioning ECM
There is no specific test for the knock sensor itself, it's a process of elimination, if the wires are good between the sensor and the ecm then there are two possible other causes, the knock sensor or the ecm with the sensor being the most common failure,checking the wiring is time consuming and requires using a DVOM and accessing the ecm to identify the wire connectors coming from the knock sensor. Check to make the sensor wires connector is on and not damaged or loose. Keep in mind that this code could also be set by an engine malfunction which could cause the engine to knock excessively, for example if the timing is overadvanced causing the engine to have preignition, the purpose of the knock sensor is to cause the computer to retard the engine timing when there is engine pinging, if the problem persists the computer(ECM)will stop retarding the timing and cause the engine light to turn on, engine pinging can also be caused by low octane fuel or engine overheating.