VEMS Community Forum

Technical => Wiring & Sensors => Topic started by: Teräsmiäs on July 01, 2018, 05:32:42 pm

Title: Tachometer ouput
Post by: Teräsmiäs on July 01, 2018, 05:32:42 pm

Hi,

I am using latest Vemstune. Firmware 1.1.95 and also i have tried 1.2.11.

Coil is using pin 24 and 34.

So i tried to change coil output 24 and 36 and car works fine so pin34 is okay.

I put tachometer channel 34 and tested with oscilloscope and there is no voltage (10mv and that is same if i disable that channel same voltage).
I also have tried channel 36. Same thing.

What is wrong ?

Title: Re: Tachometer ouput
Post by: Kamuto on July 02, 2018, 10:49:25 am

Quote from: Teräsmiäs on July 01, 2018, 05:32:42 pm

Hi,

I am using latest Vemstune. Firmware 1.1.95 and also i have tried 1.2.11.

Coil is using pin 24 and 34.

So i tried to change coil output 24 and 36 and car works fine so pin34 is okay.

I put tachometer channel 34 and tested with oscilloscope and there is no voltage (10mv and that is same if i disable that channel same voltage).
I also have tried channel 36. Same thing.

What is wrong ?

those outputs are pulling to ground probably, pin 4 is usually used for tach signal

Title: Re: Tachometer ouput
Post by: Teräsmiäs on July 02, 2018, 12:36:15 pm

https://shop.vems.hu/catalog/inductor-p-102.html?osCsid=865df4c5d41baf90a6e02e1e75eb76e0 (https://shop.vems.hu/catalog/inductor-p-102.html?osCsid=865df4c5d41baf90a6e02e1e75eb76e0)

Vems shop site says this
"Take a free ignition output (IGBT based, not logiclevel !) and connect it to the input of the RPM gauge. Beware that injector FET or other output is not suitable, would be ruined immediately!!!. "

So i ignition output needs to be used in this case.

Title: Re: Tachometer ouput
Post by: Kamuto on July 03, 2018, 10:17:59 am

Quote from: Teräsmiäs on July 02, 2018, 12:36:15 pm

https://shop.vems.hu/catalog/inductor-p-102.html?osCsid=865df4c5d41baf90a6e02e1e75eb76e0 (https://shop.vems.hu/catalog/inductor-p-102.html?osCsid=865df4c5d41baf90a6e02e1e75eb76e0)

Vems shop site says this
"Take a free ignition output (IGBT based, not logiclevel !) and connect it to the input of the RPM gauge. Beware that injector FET or other output is not suitable, would be ruined immediately!!!. "

So i ignition output needs to be used in this case.

If your RPM gauge originally got the input signal directly from the primary side of the ignition transformer (common for cars that originally had distributor ignition), or you know that the RPM gauge likes high voltage. Since 1989 most gauges are fine with the recommended EC36pin4 (p259/0) pulled up (to +12V with 1k .. 10k), but for example on old (older than 1989 ?) BMW was NOT sufficient to drive the tachometer gauge
read it full not the part :)

Title: Re: Tachometer ouput
Post by: Teräsmiäs on July 03, 2018, 10:59:28 am

I have older car -86 Saab and i have also measured that needs signal from primary side of the ignition transformer.

So the question is why there isn't signal ?

Title: Re: Tachometer ouput
Post by: Kamuto on July 04, 2018, 10:54:30 am

Quote from: Teräsmiäs on July 03, 2018, 10:59:28 am

I have older car -86 Saab and i have also measured that needs signal from primary side of the ignition transformer.

So the question is why there isn't signal ?

have you put resistor to 12v it requires pullup for the signal :) anyway p259 probably would work fine ;)