Both relays test the same resistance? 107 Ohms? I assume relay 2 is still not being grounded by the ECM. Since we don't have a way to check the IMMO module for faults, we're running out of options here. We can go through and start checking ECM grounds and see if a ground is missing, but I would expect a code or other symptoms.
I'll label all the ECM grounds so you can check them.
The issue with the Immobilizer can be difficult to diagnose just by the security light, Under pattern 1-3 the light will go On for 2 seconds and then there will be a couple different things that can happen but possibly being missed, or it can appear to be fine but the IMMO module is not sending the correct message to the ECM to ground the relay. Even lower than normal voltage to the IMMO module can cause it to fault out. The ECM needs to receive a logic immobilizer code.
This is the diagram showing how the IMMO control unit and ECM interact. But I can't suggest you replace the ECM without knowing it's at fault, they are way too expensive to try a known good module. There are just way too many possibilities here.
If you had a higher end scan tool that could show the ECM is receiving the correct messages from the Immobilizer or not, that could show one or the other is at fault.
I've been going through service info for a long time today on your vehicle, and it should be setting codes if there is a relay fault causing the crank no start, It might be time to have a shop or possibly a mobile tech to come out and do a full system scan to see if there are any codes stored in other modules. At least to tell you what the issue is.
Diagrams 7, 8 are the Grounds for the ECM. You can back probe these with a regular test light attached to a 12v source and the light should not drop out while cranking, being grounded through the ECM connectors.
But I don't want to see you replace any very expensive modules and end up with the same problem.
I'm going to keep looking for any more info and tests you can do.
Go through the fuses one more time with the test light, make sure they have power on both sides, and no fuses look like they have burnt pins, possibly heat related.
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Friday, March 15th, 2024 AT 4:05 PM