engine system malfunction indicator and warning light.

anthony pearce
Posts: 4
Joined: Wed Dec 06, 2017 3:57 pm

engine system malfunction indicator and warning light.

Postby anthony pearce » Sat Oct 06, 2018 10:43 am

Gents, Being a mechanical rather than electronics engineer , I have problems chasing the amps around the systems. I have a Subaru engine destined to run with an Alkatec ECM and OBD11 interface to Dash2 pro unit. i have gone through the resitor stage of sensor connections etc ok, but have reached a stage of wanting to maintain a clean dash layout by keeping switches and lights to minimum.
My current investigation/problem is associated with the "Malfuction indication" light requirements. The ECM has a single output which would power the standard Subaru combination meter indicator light. I would like to use one of the analogue input/drivers in Dash 2 to provide the warning .
The ECM output is 10 to 14v for a no fault, while in the event of a malfuction of the syetem the output is less than 1v. Since the Dash2 has a 5v supply for analogue devices, i am concern in getting the circuitry correct. I am seeking advice on the resistor (and diode?) requirements and circuitry to make the connection to Dash2 analogue input/output driver and to programme the display based on less than 1 v for fault indication, and that say 5v for no fault indication.

Support
Posts: 349
Joined: Mon Nov 21, 2005 4:09 pm

Re: engine system malfunction indicator and warning light.

Postby Support » Mon Oct 08, 2018 12:31 pm

Hello,

The DASH2PRO doesn't boast a designated "Engine Malfunction" warning LED as such. However you can connect the ECUs engine malfunction signal wire to one of the dashes analogue inputs (provided it does in fact have a varying voltage). From this you can create an alarm to appear on the dash when the voltage is below 1V for example. . . Additionally if you have the advanced options license installed on your DASH2PRO, you'll be able to take it a step further i.e. setting a custom alarm name to appear such as "MALFUNCTION" or to have the alarm clear itself after a certain amount of time etc.

Support(D)
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Posted by Race Technology Support

anthony pearce
Posts: 4
Joined: Wed Dec 06, 2017 3:57 pm

Re: engine system malfunction indicator and warning light.

Postby anthony pearce » Wed Oct 10, 2018 11:37 am

Are you confirming that I can connect the ECU Malfunction indicator signal from the ECU using the single cable since the ECM output signal is going tobe a voltage, varying between malfunction present at less than 1v, while no malfunction is 10to 14v.
I am expecting that this will give the alarm when the analogue device is programmed to give warning if input is less than 1v.

There is no requirement in this case to connect a 5v ref voltage as part of the circuit, as is the case with "resistance" type sensors.

Support
Posts: 349
Joined: Mon Nov 21, 2005 4:09 pm

Re: engine system malfunction indicator and warning light.

Postby Support » Wed Oct 17, 2018 2:43 pm

Yes but only if the following points are true:

You're sure the ECU malfunction wire has a varying voltage, with the range you've specified in your last post.

The dash will give you an on-screen alarm provided it has been properly configured to do this.

You'll need to connect the sensor GND (Red & Black wire from CONN B) from the DASH2PRO to a GND point in order to create the potential difference required for the analogue input. We suggest you use the same GND point that is used for powering the dash already or simply connect this to a known chassis GND.

Additionally, the 5V ref voltage output from the DASH2PRO is there to create a potential divider circuit, in order to make a normally varying resistance into a varying voltage. The dash will then be able to read the signal (via analogue inputs) & display it on-screen.

Support(D)
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