Anyway to trigger idle up when elec fans kick on???

[SPOautos]

I've got a mostly stock 6.0L L98 swapped into a 62 vintage step van. Runs great using the E78 ecm.

I'm switching the clutch fan out for two 11" Spal electric fans. Im going to use an pwm controller to control them (autocoolguy high freq pwm controller) since the e78 is trash for controlling elec fans.

Here's my question....is there a way to trigger the idle to increase when the fans are running OR if voltage is below a certain threshold so that the alt will produce a bit more current? Similar to how ac will trigger a idle up....but based on something like voltage falling below 13v at idle or fans being on.

Or any other ideas....end goal being to help boost the alt some at idle when the fans are on so the voltage doesn't fall much.....I know I can buy a high output alt but I'm trying to avoid that.

Thank you for any ideas!

[blindsquirrel]

If there were a setting to do that (there isn't), it wouldn't work unless the ECM was controlling fan activation. Using a standalone fan controller the ECM won't ever know whether the fans are on or off.

[SPOautos]

As I think about this I have another question....

Is a factory E78 with L98 a ecm regulated voltage where they typically have the ring sensor around the main ground to read power usage so that it can control the alt appropriately? I do not have that sensor.

[blindsquirrel]

You know this stuff changes year to year and platform to platform, right? There's no way to look up "E78" in the GM manuals. Year, make, model.

[TheMechanic]

Most tables from Gen 5 seem to be in the E78 also. Try this
https://youtu.be/PTyAvvlW5og

[blindsquirrel]

The OE strategy/intent of the alternator voltage control is to reduce alt output under certain conditions where it isn't needed. Just because it has settings that can be changed doesn't mean you can change them in a way that would make it work the opposite of intended. The way to modify the system to increase output, on platforms that have it, is to disable it and let it work like a plain non-voltage-control system where the internal regulator controls the field to maintain a constant voltage output at all times.

[SPOautos]

The way to modify the system to increase output, on platforms that have it, is to disable it and let it work like a plain non-voltage-control system where the internal regulator controls the field to maintain a constant voltage output at all times.

I thought on vehicles with voltage control, the alt doesn't have its own logic or internal control.

[blindsquirrel]

It does have the same internal regulator, the alternator is the same whether it's got the smart system or the dumb system. The alt can be sent a signal to decrease output below what the internal regulator would normally do. If sent no signal it does whatever duty cycle is required to maintain the set output voltage.

[TheMechanic]

https://www.dirtydingo.com/shop/page...path=4&pID=108