krisby, you have pins 1 - 5, but pin 1 isn't used and there is no connector present in the plug. The four pins that are present are 2, 3, 4 and 5.
2 (which you call 1) is 12v power so NOT ECU - the ECU works with 5V signals. 3 is the ground connection, linked to pin 4 of the ECU, helping to ensure a common ground. 4 is the 5V reference input from the ECU and 5 the signal output, which can be expected to vary between 0 and 5V.
Measuring resistances is not going to help a lot. You want to check that pin 2 is 12V and pin 4 is 5V compared to pin 3. Pin 3 should be continuous to any earth point you can find.
2 (which you call 1) is 12v power so NOT ECU - the ECU works with 5V signals. 3 is the ground connection, linked to pin 4 of the ECU, helping to ensure a common ground. 4 is the 5V reference input from the ECU and 5 the signal output, which can be expected to vary between 0 and 5V.
Measuring resistances is not going to help a lot. You want to check that pin 2 is 12V and pin 4 is 5V compared to pin 3. Pin 3 should be continuous to any earth point you can find.
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