Main fan and IC pump questions

[MVD]

Through a majority of my searches people are have used 2 prong switches (non lighted) for the main fan and IC pump and have no problems. Of the handful who used lighted switches they did not say where they picked up their 12v source from. I picked up a 12v source off the PCM but am having problems. I have also read that with lighted switches it is a good idea to run the ground right back to the battery instead of the chassis. Is this true?

So for those who have lighted switches where did you pick up your 12v from?

 

[MVD]

Apparently no one used lighted gauges when doing these mods :shrug:

 

[Dana]

I do not have lighted switches either, but you have to insure that the control circuit for the fan or pump is completely isolated from the lighting circuit for the switch. The control circuit is typically 5v and the lighting circuit is 12v. You do not want to mix them.

Dana

 

[G03SVT]

Just pick up the 12V ignition source from the radio.

 

[FireRed04Vert]

I sure wouldn't use any power source off the PCM. You're playing with fire there.

 

[FireRed04Vert]

I do not have lighted switches either, but you have to insure that the control circuit for the fan or pump is completely isolated from the lighting circuit for the switch. The control circuit is typically 5v and the lighting circuit is 12v. You do not want to mix them.

Dana

That is excellent advice. Find out what you're dealing with by using a digital volt meter.

 

[ShelbyGuy]

i have two lighted switches and grab power for them from the rear window defroster circuit

 

[MVD]

Just pick up the 12V ignition source from the radio.

I tried that but it didn't work. I also tried grabbing power from the PCM and the headlight switch but neither of those worked.

 

[Dana]

I tried that but it didn't work. I also tried grabbing power from the PCM and the headlight switch but neither of those worked.

Then you are probably using the wrong type of switch.

It should have 4 connectors on it.
2 for the switched circuit, say the fan control which would be from one of the pins on the PCM, I forget which, to ground.
The other 2 would be for the lighting circuit. One side would be from a switched 12v + and the other side would go to ground.

Dana