2000 s10 4.3l pickup electrical fans not working
 

When I got the truck the regular cooling fan was replaced with electrical cooling fans and they do not work so at idle it overheats. I put 12 volts to the fans they came on. Also when the truck did over heat the fans did pop on. But they won't pop on until it overheats. I've replaced the CTS so far and nothing what else should I do? I was just thinking about hard wiring them. But I would rather have them work correctly.

Since these trucks never came with electric cooling fans, you will likely need to do this troubleshooting yourself. Only you can determine what parts were installed & how they were hooked up. Follow the wiring from the fans and see if there is a control box with a manufacturer information on it.

Where was the CTS that you replaced? Most aftermarket fan control setups use a surface temperature probe on the radiator core itself.

The CTS was located driver side on the block. I'll dig in it some more tomorrow and look at the wiring more.

I thought it was weird that they popped on when it overheated but won't pop on to cool the motor before it overheats.

If the coolant temperature switch you have is designed for a light, it may not come on until it's too late. What temperature is it rated to switch on at?

The coolant temp sensor is what I replaced. I just put a stock one on it.

The temp sensor in the driver head is a variable resistor sensor, not a proper temp switch for tripping a relay to trigger a fan circuit.

Assuming the fan is activated via a relay, which it better be... you may be better off just having that relay triggered by an ignition source than the temp switch. Then whenever the engine is running, so is the fan, and you don't even have to worry about it.

Just my $0.02