Driving an electric water pump from DTA S80

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Rob Stevens
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Re: Driving an electric water pump from DTA S80

Post by Rob Stevens »

I don't think the Aux outputs work if the engine is not running as noted above,
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mefmotorsport
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Re: Driving an electric water pump from DTA S80

Post by mefmotorsport »

Rob Stevens wrote:I don't think the Aux outputs work if the engine is not running as noted above,
Good point,

It's strange though that AUX2/FAN works OK with the engine stopped, I'll ask Allan to confirm that.

If that's the case then it's back to the drawing board!

Thanks,

Martin
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mefmotorsport
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Re: Driving an electric water pump from DTA S80

Post by mefmotorsport »

:( :( :( I just spoke to Allan who confirmed the bad news, only AUX2 is live when the engine isn't rotating and I'm using that already for the fan control.

I think I might change the wiring to use AUX2 for the water pump and AUX6 for the fan as it's more important to keep the water pump running after the engine has stopped. I can always wire an override switch in for the fan anyway if I want it to run after the engine has stopped (or use some kind of timer relay that hangs on for a pre-set time).

Martin
VR6Turbo
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Re: Driving an electric water pump from DTA S80

Post by VR6Turbo »

The manual says only AUX 4/5/6 & AUX7/8/9 are off when the engine stops.

I've seen my intake solenoid move (AUX 3) when the engine's stopped. Mine is an older generation S80 though, the big brick :D AUX2, yep, that definitely is on when the engine is stopped as that's my fan too.

Shame the DTA hasn't got a power off timer built in. I've looked at several delay-off relays and none of them just work from an ignition cut as a trigger. They all need a positive voltage trigger.

I.e. the relay powers up when you start the car, you stop the car, take the ignition key out and the relay stays powered up for X minutes, then shuts off.

If you know of one of these, please let me know! :D
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mefmotorsport
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Re: Driving an electric water pump from DTA S80

Post by mefmotorsport »

OK, Allan confirmed that Aux2 goes off with the engine, only Fan control (being the alternative function of Aux2) stays active with no crank pulses. That will be fine for me controlling my pump, I'll use aux6 for the fan, I can accept the fan going off when the engine is stopped, maybe I'll design a timer relay using a PIC that will start timing when triggered from the ecu aux6 output. If I get one working I'll send you one!
VR6Turbo
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Re: Driving an electric water pump from DTA S80

Post by VR6Turbo »

Yes please! :D

Ideally I'd like a timer that powers up with the ECU, then just stays on for 5 minutes when the ECU shuts down. Marvellous!
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mefmotorsport
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Re: Driving an electric water pump from DTA S80

Post by mefmotorsport »

One thing I'd forgotten about, if I leave the ecu powered up but the engine is stopped, there is no "autro prime" facility for the fuel system, also no "start fuelling" by initial crank turns.

I thought about this and haven now come up with a simple solution.

Using a relay with normally made contacts wired in the ecu power feed and the coil powered from my ignition switched supply and a capacitor in the ground path from the coil, when I switch the ignition on I now have an "interrupt" or a very short period of disconnection to the ecu power which reboots the ecu and all is well.

So, I'm now using the Fan output to drive my water pump, this works when the engine has stopped and Aux6 for my Fan control, the fan stops when the engine is stopped, I can get around this with my timer relay that will keep the fan running for a preset amount of time after the ecu Aux6 signal has gone.

Martin
VR6Turbo
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Re: Driving an electric water pump from DTA S80

Post by VR6Turbo »

Cool! So is there a way to use a timer relay (or some other circuit) to leave the ECU powered up for 5 mins after you turn the car off? I want to do the same thing as you: run the water pump off Aux 2.

Actually, what kind of current does the ECU draw?
proutyc
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Re: Driving an electric water pump from DTA S80

Post by proutyc »

Mef. How well is it working. I'd been thinking of how best to do this.

Interested to see the results?

Thanks
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mefmotorsport
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Re: Driving an electric water pump from DTA S80

Post by mefmotorsport »

Yes, it's fairly simple to make a circuit that would drive a relay such that once the ignition signal was removed, the ecu would stay powered up for a predetermined time, say 5 minutes (programmable) then switch off. It would switch the ecu on again once triggered by the ignition signal.

I've never actually measured the current drawn by the ecu but I suspect it will be only small, say 250mA as all the circuits that draw big current, ie injectors and coil dont draw current via the ecu positive supply, this current only passes through the ground wires (hence why it's important to have thick short ground wires, also 2 of them)

Martin
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