Can I simply depin whichever terminals I need to test. The Mitchell guide says to connect the test harness in between the main harness connectors and the ecu to do various tests. I'm wondering if I can just remove the pin that goes to the ecu and test or do the pins need to be connected to the ecu and voltage tested actually at the ecu via the test harness.

I can't find that thing anywhere and it appears to be over 600 dollars.

I guess I can try to find those pins that are small enough to fit in between the wires so I can test if I have to. I just don't like puncturing wires.

 

Not sure which tests you are doing. Many times you are looking for something from the ECU so you'd need to be testing it and not the wire....other times you are looking for a signal from "a sensor" to the ECU so in that case the wire is fine.

Agree with you on cutting into wires, try to get the small pins.

 

The test harness is made so that you can read the voltage/signal that is being sent between the ECU and the sensor while they are connected and the system is on. Therefore removing the wire at the ECU connector won't work. It makes it much easier than having to crawl into the foot well and back probe the individual wires at the ECU.

I wouldn't waste the money on an OEM test harness. I always pull the ECU and harness out as far as I can and back probe the ECU wire harness with my needle style multimeter probes. I would not suggest using any sort of wire piercing/cutting probes. If you don't have probes that are small enough you could try sticking needles/pins to your multimeter probes.

 

GhostAccord is correct, the best way to do this is to back probe the harness connector while it's still connected to the ECU.

 

What exactly is backproing ? Is that buying a pin small enough to stick into the connector while it's connected to the ecu ?

 

Yep, from the back side of a connector, the pin slides along the wire passed the seal until it makes contact with metal inside the connector. This way is much safer than puncturing wires.