Ronny

iTrader: (1)

For N02 hookup.

I see A4-GRY (egr) in EBL connection drawing which is an unused wire to my prior EGR. That clearly goes to relay. That is circuit 436 in my service manual ECU to EGR solenoid. My other wire(egr) PNK/BLK circuit 39 per my service manual is IGN switch. That shows to feed to solenoids and relay.

I see C8 in EBL drawing to switch but do not see it referenced in EBL ECM drawing. All others are shown. Might it be a ground? Where do I pick up that wire off ECU?

RBob

iTrader: (1)

Pin C8 is an input to the ECM. Grounding it arms the N2O logic in the ECM. This is how the ECM knows that it is OK to enable the N2O relay and pull the spark timing.

RBob.

Ronny

iTrader: (1)

Is that those 10 or so inputs I see in your install directions. G-R-N occupies 3 inputs? Others 1-7.

Ronny

iTrader: (1)

Where is pin C8 within the ECU?

RBob

iTrader: (1)

See this link:

www.dynamicefi.com/RePinHowTo.php

It shows how to read the connector pins.

RBob.

Ronny

iTrader: (1)

I brought my service manual to office so will take a look. I presume my 84 Vette original wire harness has a C8? I did this once B4 when I added IAT control. Bill(speedtronics) provided that pin with HAM board. Do you have a source that I can procure one? hint-hint...

Just to double check the other EGR wire(gray) is then not used?

RBob

iTrader: (1)

HAM board, that makes it different. Pin C8 of the ECM isn't wired to any connector location on the HAM board. Can add a wire from C8 to one of the unused edge card connector locations. They are white: 1, 6, 23, & 24. Then run the arming input to that location.

Not sure what you mean by 'other EGR wire.'

RBob.

Ronny

iTrader: (1)

Ok. I am not quite understanding. I have the SM in front of me. I see unused pins
7 and 21 on harness and GM-ECU and 1 and 24 on other harness and GM-ECU. I believe I already used one of those for IAT. I can look at harness and identify which is used for IAT. I still dont understand where C8 is on EBL. Are you suggesting it is internal? I looked at your photos and I do see several C's. Do I need someone to (solder) attach C8 to the HAM? Then use the available pin loaction, as in your repin instructions? Am I close on understanding this. Can I ship EBL back to you for mods?

"other wire" The EGR has pink/black which I believe is 12V switched. That I use per your drawings. Gray is the other I referred to is identified as ECU to EGR. Is that one disregarded? Does it have any value in this discussion? I thought that was the one that goes to switch at pos #3(rear of switch) that you identified as C8. I guess not.
Thank you.

RBob

iTrader: (1)

You need to use both wires that went to the EGR solenoid. The pnk/blk goes to the switch to provide power. The gray (A4/ black 22) goes to the relay coil to provide a ground.

In the drawing, A4 is the gray wire that goes to pin F on the relay.

The pnk/blk wire is shown going to pin 3 of the arming switch.

There is then a wire added from pin 2 of the arming switch to pin D of the relay.


On the HAM board there are 4 locations that are not connected to the ECM. Even though GM may have used them in the Crossfire ECM, there is no use for them when using a C3 TBI ECM. So Bill didn't place any connectivity between them and the ECM.

Pin C8 is the location in the original pin type connector that was on that ECM. Look at the HAM board and note the two sets of two rows of pins between it and the ECM. IIRC, the end pins are labeled on the HAM board.

A wire needs to be soldered between pin C8 of the ECM, and one of the open locations on the HAM board. That location will become the arming input to the ECM. Which goes to pin 5 of the arming switch.

RBob.

Ronny

iTrader: (1)

Can I ship EBL back to you for mods?

liquidh8

ronny, i just got your PM, sorry for the delay. What is the HAM board? I just added a pin to the C connector, don't recall the color or the connector. But the factory ECM connector is the one I am talking about. I guess you have some other mods to your ECM?

RBob

iTrader: (1)

Yes.

RBob.

Ronny

iTrader: (1)

Thank you. I will ship Thurs. I do not have the connector pin so please provide one if you can.
Thanks again.
Ronny

Ronny

iTrader: (1)

Liquid. I have an 84 Vette. The GM harness is not plug and play with 7747-8746 or other donor ECM's. Donor ECM needs to be Ham'd or adapted with edge card and that was currently or formerly done by Speedtronics. So C8 is where the pin will go. That location I believe RBob explained in this or my other tread. Soon will be up and running for spray.

liquidh8

Ronny, let us know how you make out after you get it back from RBob!