Quote:
Originally Posted by BamZipPow
15A EFI fuse (engine bay fuse box) sends power through the EFI relay which supplies power through the Circuit Opening Relay to the fuel pump. The ECU gits an initial signal from the starter to close the CO relay and then stays closed via the ECU which gits it's signal from the crankshaft sensor. The CO kills power to the fuel pump in the event that the engine stops running (crank shaft sensor). It's a safety feature so the fuel pump doesn't keep pumping in accident if the engine stops running and the fuel line is compromised. You should be able to see if the CO relay is sending power to the fuel pump by connecting some wires to the top of the fuel pump contacts (on top of the fuel tank) and testing fer 12VDC.
The EFI fuse also supplies 12VDC power to the +B of the ECU. This is what powers the Check Engine light. If yer Check Engine light is not illuminated in the Ignition On position, I would check that fuse carefully/replace it or trace power from that point. There are 2 branch connectors from the EFI fuse along the way to the ECU. You should be able to test the +B power on the Diagnostics port located in the engine bay on the air plenum. If there is no power at the +B, you can use at least a 12 gauge wire from the battery to that test port and see if the Check Engine light illuminates. If it does, you should be able to test if the engine will fire at this point. If it fires, then it will be along the EFI fuse wire harness to the ECU. 
You will need to build a simple test harness to check fer power along the various components. I'm using a long length of Cat 5 network cable and alligator clips attached to the end. This allows me to test from anywhere along the vehicle with my multimeter. |
Thanks Bam.
*Someone on the You-Tube Toyota forums mentioned that the Circuit-opening relay knocked his vehicle out of service.It's on my list of things to check.
*the Haynes manual is also pointing at the Knock sensor as being associated with ignition timing (ECM & Igniter).
*they also talk about the MAF sensor as part of the ignition circuit.
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*EFI fuse was okay
*EFI Relay was okay
* my schematic shows that the 10-A 'Gauge' fuse powers the Check Engine Light.I'll verify that.thanks!
*I have voltage to the 'BATT' portal at all times.
*I do have power to the B+ portal when the ignition is on and cranking.
*Crankshaft Position RPM sensor is new and in range for impedance,but I need to test it's AC output while cranking.
*Camshaft Position Sensor is new and in range impedance-wise,but also need to check it;s AC output.
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*Twilight Zone showed up with ScanGauge. With the ECM removed from the kick-panel and grounded with a jumper,the ScanGauge will 'connect' and allow 'Scan' function.
*if I mount the ECM back in its place,the ScanGauge will NOT connect with the ECM.
*So somethin's squirrelly with the harness connectors that I've got to look into.
*as of yesterday,I could get the Scan function to reappear,but there were no codes stored and I never 'cleared' the 1300 code.Quirky!
* since the electronics are a complete system,and all the connectors have to connected simultaneously,I'm having to pierce wires with a needle and attach the DVOM to that,take my readings,then seal the wire with liquid tape.