So i got my tach and amp installed.

But when i start the car, the tachometer does a sweep to 5.1 or 6 and stay there and doesn't go back to 0 and start working :/

I bought an aftermarket tachometer from someone a while ago and i can't remember who it was, he made them and yeah :/

I got an idea!
Remove the power steering pump and glue/JB weld some small magnets onto the back of it, then use a hall effect sensor to pick up the signal and send it to the tach.
Obviously not as easy as it sounds, as you would have to do the following:
Make sure you place the magnets on opposite sides of the pulley to keep it balanced.
Mount the hall sensor close enough to the magnets that it picks it up.
Feed the hall sensor 12V from something.
Use a voltage divider circuit to step down the voltage from 12V to 1V, a 220ohm and 20ohm should do it.



Anyone think this will work?

Here are the links to some parts:

https://www.mcmaster.com/5862K23/

https://www.digikey.com/en/products/detail/littelfuse-inc./55505-00-02-A/1237226?utm_adgroup=&utm_source=google&utm_medium=cpc&utm_campaign=Pmax_Shopping_Product_Silicon%20Valley%20Category%20Awareness&utm_term=&utm_content=&utm_id=go_cmp-20773039395_adg-_ad-__dev-c_ext-_prd-1237226_sig-CjwKCAiA_5WvBhBAEiwAZtCU7806fJ0g9pjScjNiiOpLpAxXRl9Bma3VBgiUgEUM_UopTVAH4Br0XhoCwxQQAvD_BwE&gad_source=1&gclid=CjwKCAiA_5WvBhBAEiwAZtCU7806fJ0g9pjScjNiiOpLpAxXRl9Bma3VBgiUgEUM_UopTVAH4Br0XhoCwxQQAvD_BwE