Okay last test for today, and then try a couple new OEM Honda relays. Same test, just with the ECM connector E unplugged. Test light hooked to Ground and touching with the tip to pin 3 with key Off, and key On. That will verify there's nothing internal to the ECM that could be limiting current flow preventing the test light bulb from illuminating.
Pretty much after this, we will try the new relays with the correct resistance. If things don't improve we'll need to load test circuits. This is what I use for load testing (pic), it's a turn signal bulb with 2 filaments. One filament is 4 amps, and the other is about 1 amp.
To load test a circuit, (an ECM ground for example), the load test light will be hooked to battery positive, then I'll disconnect the ECM connector and use its Ground wire in the ECM connector to ground my load tester, if the lamp lights, I know that ground circuit can carry either the 4amps or the 1amp, depending on how much load I want to put on the wire.
At the same time, I will voltage drop that wire with the load on it, having the multimeter hooked in parallel with the load test light. So, if the test light does not light, I'll know what the voltage drop is on that ground wire.
The same can be done with a power feed, you just have to make sure you're not pulling those 4 amps through the module (ECM is this case). You're only going from its connector to power or ground source.
This test must always be done before condemning any modules. Along with any inputs or outputs checked to make sure there isnt something else causing the ECM to act strange, not activating components/circuits.
The reason for load testing power and ground feeds is that normal test lights only pull a few hundred milliamps and that is not enough to verify wire integrity. Even with a resistance test, there can be just one strain of wire left, and that will check out as zero ohms of resistance, but it will not carry enough current for the module to operate.
We will also need to load test the pin 3 to E17 wire. Although relays only pull about 200ma at most.
I assume when you turn the key On, the security light only comes on for 2 sec then goes out? I've had others suggest checking the Immobilizer or ECM live data for any data PIDs having to do with the security system. One was pretty sure this was an Immobilizer fault, but the scan tool you have can't access the security system module, so that is tricky part here. Since the circuit we are dealing with is the IMMO circuit.
I'll post a diagram for you showing exactly how to do this, because if you accidentally pull 4 amps through a module it will be damaged. Another long post today.
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Wednesday, March 13th, 2024 AT 2:44 PM