Cool, got it...thanks guys.

 

I promise I'm not completely dumb too. I must be missing something though.

These are two opposing statements as far as I can tell....

 

The diagram that Nonnie posted up, along with others, appear to be the diagrams for the Nelson type wire harness which uses the (+) tap (green wire) of the AC clutch to activate the second fan. They've been somewhat modified... and in the case of that one the verbiage for the A/C clutch was not removed but the line schematic shows going to a switch contact and to ground. Trace it and it goes to the coil of a relay which has positive voltage on the other side of it. It confused me also when I first looked at it and read the verbiage, hence me telling Nonnie that it wouldn't work because the A/C clutch is a positive voltage. That lead should say PIN 33 of the PCM which provides a ground to complete the circuit and close the relay.

Again anyone reading this..... it is really simple. If you want to use 2 pin controlled e-fans 99-2007 use the attached schematic to wire up a harness and have your PCM tuned to use both pins 42 and 33 of the PCM.

EDIT:
Here is a description of their operation.

Cooling Fan Control - Two Fan System

The engine cooling fan system consists of 2 electrical cooling fans and 3 fan relays. The relays are arranged in a series/parallel configuration that allows the powertrain control module (PCM) to operate both fans together at low or high speeds. The cooling fans and fan relays receive battery positive voltage from the underhood fuse block.

During low speed operation, the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. This energizes the low speed fan relay coil, closes the relay contacts, and supplies battery positive voltage from the low fan fuse through the cooling fan motor supply voltage circuit to the left cooling fan. The ground path for the left cooling fan is through the cooling fan s/p relay and the right cooling fan. The result is a series circuit with both fans running at low speed.

During high speed operation the PCM supplies the ground path for the low speed fan relay through the low speed cooling fan relay control circuit. After a 3 second delay, the PCM supplies a ground path for the high speed fan relay and the cooling fan s/p relay through the high speed cooling fan relay control circuit. This energizes the cooling fan s/p relay coil, closes the relay contacts, and provides a ground path for the left cooling fan. At the same time the high speed fan relay coil is energized closing the relay contacts and provides battery positive voltage from the high fan fuse on the cooling fan motor supply voltage circuit to the right cooling fan. During high speed fan operation, both engine cooling fans have there own ground path. The result is a parallel circuit with both fans running at high speed.

Important

The right and left cooling fan connectors are interchangeable. When servicing the fans be sure that the connectors are plugged into the correct fan.

The PCM commands the low speed cooling fans ON under the following conditions:

* Engine coolant temperature exceeds approximately 94.5°C (202°F).
* A/C refrigerant pressure exceeds 1447 kPa (210 psi).
* After the vehicle is shut OFF if the engine coolant temperature at key-off is greater than 101°C (214°F) the low speed fans will run for a minimum of 60 seconds After 60 seconds, if the coolant temperature drops below 101°C (214°F) the fans will shut OFF. The fans will automatically shut OFF after 3 min. regardless of coolant temperature.

The PCM commands the high speed fans ON under the following conditions:

* Engine coolant temperature exceeds approximately 104.25°C (220°F).
* A/C refrigerant pressure exceeds approximately 1824 kPa (265 psi).
* When certain DTCs set.

At idle and very low vehicle speeds the cooling fans are only allowed to increase in speed if required. This insures idle stability by preventing the fans from cycling between high and low speed.

 

It's good to see that my schematic gets a lot of use.

 

Yes it is. Great job on that by the way! Don't/Didn't you actually make the harnesses for Nelson Performance?

 

good heaven's, no.

I did the wiring on my truck, though.

 

Has anyone converted their PermaCool Cool-Pack fans to run off PCM control? Just throwin it out there... Thanks.

 

Ah! It all makes sense now!

But where do you get the "hot in run and start" wire from? This is just the trip wire to the relay and will not be pulling much power, correct?

 

Pin 42 in the blue PCM connector and Pin 33 in the green connector? Pin #42 is empty in the blue connector but I already have a pin in #33 on the Blue connector.

 

Yep, they are on different connectors.