Quote:
Originally Posted by Tcoat
Your issue doesn't sound like the starter battery at all. If you turned the key and had slow crank or just clicks and no crank then the battery would be suspect. When you turn the key and there is nothing at all but it starts without hesitation on the second tray it means the battery is fine but you are not getting signal to the ecu for some reason. A bad switch wouldn't care what temperature it is and should be repeatable no matter what the weather conditions are so you need to keep digging.
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That's the point though. The ECU gets the signal just fine... It just refuses to do anything with it.
Everything is working fine - All the switches and relays work, but the circuit that grounds via ECM pin 26 is closed
before all the other circuits close. That is all...
Theoretically, you shouldn't be able to turn the key fast enough to "beat" the relays, unless something is sticky or the initial voltage just isn't quite there... But you can simulate the condition in an MT car by leaving the clutch out... Hold the key to start, then press the clutch. You just completed the circuit, but nothing happens, because the ECU won't complete the ground for pin 26... Because reasons... And some internal start logic that I'm not privy to...
BUT, if you do the same thing in the car on the right side of the diagram, the car starts as soon as the clutch hits the switch. The only difference between these two is that one relay circuit terminates at a plain old ground, and the other disappears into a "logic box."
Here are two starter circuits to illustrate my point. FRS, and an older car.