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Aux output high side drive issue


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Hello all,

I'm having a puzzling issue with Auxiliary output number 8 on my Xtreme ECU.

Aux 8 is setup as a high polarity driver (drives battery voltage to output) and is switching a 12V relay with an impedance of around 80 ohms. The reason i am high driving it is i don't have a 12V ignition switched source nearby.

When in test output mode 'ON', Polarity set to HIGH and Driver type set to HIGH the Relay turns on and off as expected without any issue.

However when you assign the output to 'Starter Solenoid', flick the key to the start position the relay does not enable. I can see the ECU getting the crank signal and the ECU turning on the output but the relay doesn't energize. I have tried changing Polarity and Driver type with no success.

On further investigation i found that the output will drive an LED ok under the starter solenoid condition but not the relay. Furthermore investigation i found that under test mode the output provides 13.4V but when under the starter solenoid feature the output only provides 11.8V even when both the Polarity and Driver type are set to high.

Latest firmware revision installed

Possible bug with the firmware or something else?


Link starter issue 1.PNG

Link starter issue 2.PNG

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58 minutes ago, Kitto said:

i found that under test mode the output provides 13.4V but when under the starter solenoid feature the output only provides 11.8V even when both the Polarity and Driver type are set to high.

11.8V should be enough to engage a relay.  Or was that measured without the relay connected?  

I tested this function on an ECU here and get close to battery voltage out with a 47ohm load connected.  Can you pull the aux 8 wire out of the ECU connector and measure its resistance to ground - just to confirm there is no short somewhere.  The symptoms you see suggest it may be overloaded.  My poor 0.25W resistor didnt like 3W going through it for long.

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With the relay connected i'm getting 0.5V across the relay when in starter solenoid function.

When in test on function i'm getting a good 13V across the relay and the relay enables.

For some reason, ONLY when i switch to starter solenoid function the available current is zip, barely enough to drive a T10 LED, relay coil brings the voltage down to 0.5V.

Output 8 resistance to earth with the ECU harness connector disconnected or connected is open circuit.

Resistance of Aux 8 wire itself from ECU to relay is 1 ohm.

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23 minutes ago, Adamw said:

I mean resistance between Aux 8 wire and ground, it should be about the same as your relay coil but I want to confirm


79 Ohms.

Measuring Aux 8 wire at the ECU connector through the relay coil to ground.


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Just now, Adamw said:

And this is definately a G4+ Xtreme, not a plug-in etc?  Do you have one of the other high-side capable auxes available to try?  Can you attach your map also.

Black Xtreme wire in - i wired it in :)

I was just thinking that, I'll try Aux 7 next which is for the boost control solenoid.

I can attach my map, but there's nothing to it.. Engine hasn't been setup or any tuning done at all yet, literally just IO configuring so to speak.

Note to add, i have tried other relays as well, Even tired a 2W incandescent 12V bulb - no go. But again, it will drive the light bulb with the test function on.

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Exactly the same issue. Tried it with Test on mode with Aux 7 - perfect, also tried the incandescent lamp - perfect. Tried it under Starter Solenoid feature, no go.

I did try something else to make sure when an the cranking signal was active the output comes on.

I setup Aux 7 as a GP output > Cond 1 only > Enable when DI 7 High > Driver type High Side. Worked perfectly! With the key in the cranking position (Input 7 high), Aux 7 would illuminate the bulb.

Certainly seems to be an issue with the Starter Solenoid feature or possibly any feature that drives a high signal? Or i do have a config error. I'll upload my map shortly.

See attached photo for what i did to get the output to come on with cranking signal high. 

Link Starter Issue 3.PNG


Think I've found a bug / the cause!

Under Aux 8, Select Starter Solenoid > Select Polarity - High > select driver type - High > Perform Store > Power cycle.

ECU reverts Driver type back to LOW. Does not save HIGH driver type.

Map attached.

Link Starter Issue Adam PCL.pclr

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Ok, thanks the map helped.  There is definitely a problem with this function.  I was testing on a Thunder earlier, if I load your map into a Thunder it works as expected and power-cycles fine etc.  However if I load it into an Xtreme it does behave odd and reverts to lowside after a powercycle as you mention.

Im not sure if this is a hardware limitation in the Xtreme or a firmware problem.  I will question engineering about it tomorrow.

Unfortunately I think your only option now is to change the wiring to work with lowside because it may take some time to fix assuming it is fixable.

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Haha, so i'm not going mad!

Surely it cannot be a hardware issue with the Xtreme? It works under test function and GP Output function, just not under the Starter Solenoid function, Points towards a bug within the firmware?

That's ok, i'll leave it as is for the moment. Be another 3 months before the car is operational anyway. In the mean time i'll just have to hold the key while starting. :D

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Ok, I have just taken a closer look at this today.  The reason it was working on my Thunder is because it had the latest test firmware in it and this bug has been fixed.  I just updated my Xtreme to the latest test firmware and tested your map and it is all working fine.  So I can confirm this is fixed and will be in the next release.  I dont think public release is too far away.

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