12v to 5v

[tc442]

Does anyone know how to convert 12volts to 5 volts? I am trying to find a way to tell the auto tranny in my 88 3.0 4runner that the engine is at full operating temp. so the overdrive will stay engaged. I have gone through 4 different thermostats to try to correct the problem to no avail. Any input appreciated...thanks

[odog96]

Originally Posted by tc442

Does anyone know how to convert 12volts to 5 volts? I am trying to find a way to tell the auto tranny in my 88 3.0 4runner that the engine is at full operating temp. so the overdrive will stay engaged. I have gone through 4 different thermostats to try to correct the problem to no avail. Any input appreciated...thanks

One way to do it is to make a voltage divider using 2 resitors.Since
you want to split 12v to 5v, try soldering a one end of a 6k ohms resitor to power & solder one end of a 4k ohm resistor to ground. Then solder the the open two ends of resistor together and this becomes your
feed into your temp read. The important thing is the ratio in value of the
2 resistors you use. Notice 4k is 40 % of total resitance ( 4k + 6K) which will give you a 4.8v which should be close enough. If you wanna
go even simpler use 2 - 5k ohm resistors and then you'll get 6v output.
Not sure if this is too high of a voltage? Either use an ohm meter to check the voltage after you solder this on. Also make sure the resistors are in 'k' ohms.

[tc442]

Thanks for the help Odog...I will give it a try..are amps affected by the resistor or do I need to worry about them?

[odog96]

sorry it took me a while to get back to you, I was out of town. The current (in amps)is determined by the the amount of resistance across the voltage drop. V=IR, so for 12v a total resistance of 10k will give you 12v/10kohms = 1.2 mA. If this isn't enough current for the temp sensor then you can try going down to 1k ohm total, which is 600 ohms plus 400 ohms. This will give you 12mA. I hope this helps some.

[tc442]

odog, I appreciate your help. I am probably over my head with this but I gotta try. My job is moving 30 miles further from where I live, and with the gas prices 8-10 mpg isn't gonna cut it...lol Wish me luck and thanks again..........(anybody else having problems like this on thier auto 4 runner?)