Hi All,
Running into an issue where my EMU black is “disconnecting” from the computer via USB connection only while cranking. It goes form the green connected, straight to disconnected while cranking. Once I’m done cranking, it will go back to connected as if it’s loosing way to much voltage cutting out the ECU power. This is on a 2JZ / S14
If i disconnect the starter solenoid circuit and leave everything else in tact, it will NOT disconnect from the laptop. I’m assuming the starter is drawing too much current and the ECU is dropping below the valid voltage threads hold to stay on?
The car has a VERY hard time starting and idles horribly IF i do get it on.
ECU B13 battery 12v constant power is connected to battery w/ 20amp fuse
ECU G18 Ignition 12v switched (received +12v at wire at ECU when on ON/RUN)
ECU B27, B28, G17, G24 power grounds are grounded through the harness to the engine’s intake manifold.
The engine has ground wire from black to chassis and from head to chassis.
Thank you all for the help and assistance.
A log would be great to help diagnose this
More then likely the battery is dropping very low under cranking, Black is stable as low as 6V. Anything below 10 volts under cranking is considered bad for the battery, though really seeing it dip to around 9 ish is pretty common
Yes a log would be helpful, but what i dont understand is…if it disconnects i assume it completely shuts down. So how the engine can start then?
So it must come back during cranking and probably just when starting the cranking ur voltage shortly drops so deep that everything shortly shuts off.
Maybe this can be seen in the log or do an oscilloscope measurement of bat voltage.
So probably ur battery is bad…starter bad…or somewhere a bad spot in the wiring…or ur engine needs too much power to turn.
I will try and get a log. Thank you for that. First standalone so still getting used to it. I do have the EDL1 as well.
It’s a brand new battery so I suspect the starter is bad.
Correct, it drops so low that the ECU loses power therefore cutting out power to vital sensors and engine components. Once I let up on the cranking is when it comes back above 8V’s which is why you see the laptop connect again.
The ECU is never seeing below 7V, however this is too low for it to stay on and connect to the laptop which is why it drops out.
Check your grounds too.
I’d also bet the Black is getting voltage below 7V but isn’t able to log
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