S80 AUX2 PWM won't drive SSR

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rickp2660
Posts: 3
Joined: Thu Aug 19, 2021 4:36 pm
ECU Model: S80 Pro
Firmware Version: 89

S80 AUX2 PWM won't drive SSR

Post by rickp2660 »

Hi Everyone
I'd really appreciate some help/advice on getting the S80 AUX2 output to control a Davies Craig EWP via PWM control.

I'm trying to run a Davies Craig EWP80 via a Crydom D1D20 SSR from the AUX2 output. AUX 2 has been setup as the DTA recommended settings to use water temperature input to duty % with 50hz frequency.
No matter what I set the AUX2 duty to at the SSR will not output to supply the pump. I've tried changing the AUX duty with the ignition on, setting all to 100% or all varying duties, but the pump doesn't run, even tried with the engine running.
If I use the ECU test function and switch on AUX 2, the pump switches on via the SSR and runs at full speed.
I've tried a scope on the AUX2 output. This shows the output pulse, but this doesn't seem to change in relation to adjusting the duty cycle.

The SSR is connected with AUX2 to input -ve, +12V to input +ve, then +12V to output +ve and output -ve to the pump. I don't have a pull up resistor on the input, but as I understand it the S80 doesn't need one to operate.

I've also tried all of the above on AUX3 with exactly the same results.
With having an ECU with the capabilities it seems daft to have a separate pump controller.
I'm hoping I'm missing something obvious with the setup, but I'm pretty much out of ideas and any suggestions would be welcome.

Thanks, Richard
stevieturbo
Posts: 3577
Joined: Tue Aug 02, 2011 12:08 pm
ECU Model: No ECU
Location: Norn Iron

Re: S80 AUX2 PWM won't drive SSR

Post by stevieturbo »

Bench testing or engine running ? Pretty sure the aux's need engine running ?
rickp2660
Posts: 3
Joined: Thu Aug 19, 2021 4:36 pm
ECU Model: S80 Pro
Firmware Version: 89

Re: S80 AUX2 PWM won't drive SSR

Post by rickp2660 »

Thanks for the reply.
The majority of testing I've been doing with with the engine off, so will have another run through it with the engine running.
SMR
Posts: 137
Joined: Tue Jan 16, 2018 9:38 am
ECU Model: S100 Pro
Distributor: DTA
Location: Aberdeen

Re: S80 AUX2 PWM won't drive SSR

Post by SMR »

As Stevie says, pretty sure engine needs to be running for the Aux outputs to work.
rickp2660
Posts: 3
Joined: Thu Aug 19, 2021 4:36 pm
ECU Model: S80 Pro
Firmware Version: 89

Re: S80 AUX2 PWM won't drive SSR

Post by rickp2660 »

Thanks again for the replies
You were spot on, it does need the engine running for the aux to output.
Tweaked the duty with the engine running and its running the pump fine, altering speed with duty.
Like a simple fix (even if it was me missing the obvious😁)
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