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cel indicator for knock

Lawrence martin

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hi ive been trying to follow these instructions for setting the cel to flash when indicating knock, but setting virtual aux to cel doesnt give you any switch settings nor does setting an aux output to cel give you any settings to play with

what am i doing wrong here?






Hi Ryan,

You can do this quite simply with the functionality that the G4 has.

First you set a Virtual Auxiliary to CEL.

Then you set the Auxiliary that runs your CEL to:

SW Cond 1 : Aux Virtual Value (1 if you used Virtual Aux1)

SW Cond 2: Knock > Value (What ever knock level you want it to trigger on).

Switch Logic: Cond 1 or 2.

This will mean your CEL will operate just as before, and also when knock goes over your set level. It will not store a fault code though.

If you wanted to get really tricky, set a GP Output to Knock level, feed it back into a spare An Volt. When this goes to ground it will set off the CEL and store a fault code to the AnV you selected!

Hope that helps.


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Hi Lawrence,

Apologies for the delay in getting this done for you.

I have modified your base-map and tested it for you, and it seems to work well. The instructions you had were rather brief, below is an outline of what I have done. I am not sure which Aux channel you have your CE light connected to, so you may need to modify the basemap I have emailed to you. I assumed aux 1.

1) In ECU settings set Virtual Aux 1 (or whichever virtual aux you wish to use) to CE light
2) In ECU settings set Aux 1 (or whichever aux your CE is connected to) to GP Output
3) Set Switch logic in Aux 1 to 'Cond 1 OR 2'
4) Set SW Cond 1 to Aux Virtual Value 1 = ON
5) Set Aux Virtual Value 1 = ON to 1 (or whichever virtual aux number you decided to use)
6) Set SW Cond 2 to Knock > Value1
7) Set Knock > Value1 to whatever minimum knock level you want the check engine light to come on at.

Let me know how this goes for you,


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