Seeker1056

I am doing a lq4 swap into a 67 chevelle
I wish to retain the pcm starter relay
I am unclear as to how the keyed start position from the car hooks to the pcm to tell the pcm to engage the starter

I assume there must be a pcm pin to recieve the start signal from the key, and I assume it will be 12v and not a ground signal??
the harness and pcm are 2003 van and are blue and green

can anyone shed light on how to wire this up from the key to the pcm?

thanks

ls1nova71

iTrader: (4)

It isnt controlled by the PCM. In a factory set up its controlled by the BCM. Just use the NSS mounted on the side of the transmission and wire your starter relay to that. You can also use it for back up lights. That's what I do since its easier to get it adjusted so it works like it should rather than trying to hook up the column mounted one that is usually off a bit just because of loosness in the linkage.

Seeker1056

I am not understanding your post - the keyed starter wire already runs through the neutral switch on my floor shifter and would then go directly to the starter in my chevelle.
I wish to use the pcm controlled starter relay that is wired into my pcm harness
I have a starter relay wire from the pcm that goes to a starter relay
I do not have a bcm
I need to know what triggers the pcm to trigger the starter relay which DOES come from the pcm to the starter relay in my harness
Are you saying that in the 2003 van the key/start wire from the ignition switch goes to the bcm which in turn sends a signal to the pcm which then tells the pcm to turn on the starter relay?
if so - then my question is how to signal the pcm to initiate the starter relay without a bcm

thanks

ls1nova71

iTrader: (4)

Do you have an aftermarket harness? Is this wire you speak of a heavy gauge purple wire? If not, what color is it and which PCM pin is it on? The PCM does not control the starter relay. there is VATS, but all the PCM does is shut off the injectors and it's the BCM that doesn't allow the starter relay to engage if the correct key isn't in the ignition. Basically the way VATS works is if the incorrect key is used, the BCM sees it and it tells the PCM to not start the engine, which it does by shutting off injectors. The wiring is pretty straight forward, from the key switch the start wire goes to one side of the coil side of the relay and the other is grounded by the BCM. Then the other tow are constant power and the wire to the starter itself.

Seeker1056

my van harness pcm does have a starter output wire - I will have to look tonight to see color and pin number
are you trying to tell me that this wire prevents the starter relay from working in some fashion rather than enables it?
so if the bcm is the trigger for the ground on the relay - how does one hook up without a bcm and still use the relay?

or - I guess the answer is don't use the relay at all, delete the pcm pin, and just use the car starter wire as it was hooked up before?

Seeker1056

thanks LS1nova
I think I have it now - my head was wrapped around my aftermarket LS relay fuse box having a starter relay, and my pcm having a starter output or input wire - and now see neither are interconnected
I will just delete the pcm wire, and use my car start wire as before the swap