Multi meter testing sensors

[PlenumBiscuit]

As the saying goes....dont throw money at it, it could be a wirin g fault

Anyways so ive got a multi meter haha what next

do i take a sensor off and test the resistance/continuity? i ried this say on a cam sensor and theyve have 3 pins so i get no response

also if testing whilst sensor and ignition is on, how can i work out which wire is power, signal, ground without blowing the ecu up

i have probes to wedges into the plugs

ive been through 20 youtube videos and they all drive me nuts lol

anyone know any brilliant vids how how to do this holden style?

or any above advice cheers...

 

[07GTS]

3 wire engine sensors are usually power, earth, signal return, usually 5v so when plugged in and powered up u should have earth, 5v and signal will be somewhere from 0-5v depending what the sensor is doing if it goes past the teeth its reading it will be close to 0v then when its just in a gap it will be close to 5v,

if ur using multimeter then ur pretty safe and wont join any wrong wires, its when test light is used that causes those issues as test lights add load to the circuit tested where a multimeter just reads voltages, a sensor circuit like cam, crank 3 wire are designed to collapse (signal pulls 5v down to zero) so if a test light was used the test light itself would pull the circuit down to almost if not zero so always use multimeter, just if ur probing dont let the 5v power touch earth as it may damage the ecu output thats bout all u could damage, the 5v signal is fine to collapse

resistance only shows that the sensor is not open circuit which isnt much as some can be until powered up in which then u cant test resistance, resistance is mainly ok for testing sensors with coil windings in them to see coil resistance, but with cam, crank sensors keep it hooked up and probe in and power up find ''signal power'' and earth then get piece of metal and place it on the sensor end (same as sensor going past teeth inside) and it should pull the 5v down to zero, then if u move the metal away it will go back to 5v, if it dosnt then try the other 5v as one will be power and one signal,