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Old 03-31-2021, 10:13 PM
colorado80439 colorado80439 is online now
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Default ECU power question?

Looking for suggestions, we are chassis wiring and do not have the engine wiring harness yet. (E38 ecu) we're installing a battery disconnect next to the battery controlled from a toggle switch at the instrument panel. I'm questioning whether we need to have constant power to the ECU if I will be using the battery disconnect frequently. IE bypassing the battery disconnect to power the ECU

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Old 04-01-2021, 06:31 AM
dhutton dhutton is offline
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Yes you do or you will lose all your fuel trims etc every time you remove power.

Don
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Old 04-01-2021, 08:13 PM
colorado80439 colorado80439 is online now
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Quote:
Originally Posted by dhutton View Post
Yes you do or you will lose all your fuel trims etc every time you remove power.

Don
Thanks Don, you're the man.
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Old 04-02-2021, 12:52 AM
65 Drop Top 65 Drop Top is offline
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I believe you can use a small fused jumper wire to keep the ecu memory.

Last edited by 65 Drop Top; 04-02-2021 at 12:55 AM.
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Old 04-02-2021, 08:04 AM
colorado80439 colorado80439 is online now
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Quote:
Originally Posted by 65 Drop Top View Post
I believe you can use a small fused jumper wire to keep the ecu memory.
OH! I like that idea, I'll research that for sure
Thanks so much!!
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Old 04-02-2021, 08:53 AM
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572Camaro 572Camaro is offline
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American Autowire sells a “lifeline” which is a small circuit breaker that can bypass your main disconnect switch. If you trip the breaker, it auto resets.

I don’t know anything about your ECU but most aftermarket EFI companies want you to run power and ground directly to the battery.
I run FAST and they demand it due to electrical noise.
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Old 04-02-2021, 01:24 PM
65 Drop Top 65 Drop Top is offline
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I suppose a breaker would be better than a fuse.

Another option, which is more involved and costs more, would be to use a battery back up. I saw a guy use one of those mini lithium ion jump starter batteries. He used it primarily for car stereo memory, but ecu memory should be the same. And if your car battery ever dies, this can jump start it. It’ll charge phones or laptops too.
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Old 04-03-2021, 07:23 PM
colorado80439 colorado80439 is online now
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Quote:
Originally Posted by 572Camaro View Post
American Autowire sells a “lifeline” which is a small circuit breaker that can bypass your main disconnect switch. If you trip the breaker, it auto resets.

I don’t know anything about your ECU but most aftermarket EFI companies want you to run power and ground directly to the battery.
I run FAST and they demand it due to electrical noise.
That's great, I think I may run a 20 amp version so I can use the power door locks with the battery disconnect open.
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