Connecting to e67 Ecu for ac fan control on a LS Swap

[arriusone]

I have been reading the various threads here for quite some time and the information from all you folks has been immensely helpful. I have installed a LS3 crate engine with a Vintage Air and a T56 Magnum transmission in a 67 Firebird.The engine controller is an E67 ECM. I have found a lot of information on other ECM’s but not much on the crate motor ECM.

AC and Fan strategy -
From what I understand I cannot use the E67 ECM to control the AC compressor and fans together because I do not have any data link from a Body Control Module so I need another strategy. So I am planning to use the VA trinary switch to turn the fans on when the AC is turned on. However, I do not want the fans running full blast all the time. Similar to several other threads my thought is to do a series/parallel fan setup. The following diagram shows my idea. The low speed and high speed fan connection to the ECM should handle all the engine cooling requirements with the low speed also handling the AC requirements triggered thru the trinary switch.

Is this possible with an E67 ECM? The ‘as received’ wiring has only one fan connection in the relay/fuse panel. However the low speed fan (C3 pin 49) and the high speed fan (C1 pin 54) are connected to a single fuse. I am assuming I can separate these for my series/parallel fan setup?

To protect the compressor I am thinking I can put in a NC rpm window switch to shut the compressor off at a set rpm – say 4000rpm. Several friends do not have rpm protection in their LS installations and have exploded a couple of compressors, literally.





I am still unclear about a few things.

1. Is it possible to get idle bump when the AC compressor turns on? Or do I just increase idle speed to compensate?
2. Is there a signal to the ECM maybe from the electronic throttle pedal that I can use to disable the AC compressor on WOT?

Reverse Lock Out –
My second challenge is with the reverse lock out solenoid actuation in the T56. Can I enable C3 pin 8 in the ECM and connect it directly to the solenoid on the transmission? Or should I go thru a relay?

My challenge has been that there was no wiring diagram with the instructions that came with the electrical kit and the pin out descriptions are unclear. For example non of the pins are identified for the fan control. I have been extrapolating the pin outs and functions from a combination of Corvette and Cadillac ECM information.

Appreciate any thoughts and comments.