Having spent the morning researching the 1227165 parameter for controlling the fan relay, I'm still not sure which is correct for 1986 to 1989 F body TPI cars.

I've cross referenced all wiring diagrams which seem to indicate all cars had normally open contacts in the fan relay so I would think that the parameter should be checked for N/O.

But, going through the BIN files for each year it appears that all $32 and $32b BINs had normally closed contacts so it is unchecked. All (or most) $6E BINs had normally open contacts so they are checked.

This doesn't jibe with the wiring diagrams.

I had always thought that all F body cars were Normally open contacts and that all Y body (Vette) were normally closed contacts but now I'm unsure.

Anyone have any knowledge or a place to check this information? I would appreciate it.

 

The difference is in the a/c pressure switch on D11, there is not a standard n/o or n/c for f-bodys although most are n/c and y's are n/o. I have seen in the schematic the switch being wrong as well.

 

Thanks. I think you mean f bodys are N/O and y's are N/C? Correct? I've looked at all of the 165 $32 bins and the are N/C. Most all $6E are N/O. Are you saying the A/C switch is what determines the open or closed? I thought that only came into effect on second fan and only off of the manual head switch. Thoughts?

 

I think the a/c switch determines the n/o or n/c setting in the ecm. But heres one I did a memcal for a buddy switching from 32 to 6e a while backed he ripped out his a/c so I left it n/o. The fans ran all the time and I had to change it too n/c to get them to function so I don't know the answer for sure.

 

This is what I have concluded after going through all the Bin files for 1986 through 1992 V6 and V8 F body cars and comparing them with the wiring diagrams.

In all cases, 86 through 87 cars had the n/o fan parameter unchecked so that means they must have n/c contacts in the fan relay. It does not show that in the wiring diagrams nor does it show any connection to the A/C pressure switch. The ECM does receive a ground input from the pressure switch when A/C is on but that's it.

1988 on up are different. The V6 cars are the same as earlier V8 cars in respect to simplicity but they do have n/o contacts not n/c.

5.0 throttle body cars are different with a temperature switch in the head for on and off operation and have one fan with no ECM connection. parameter is n/o but it doesn't matter as there is no ECM control.

5.0 and 5.7 TPI cars have 2 fans with a more complex system where the primary fan is controlled by the ECM and the auxiliary fan is controlled by both a temperature switch and the a/c pressure switch. Kind of a fail safe system. All have the parameter as normally open in the bin. In other words the parameter is checked.