So I put a 05 LQ9 motor/ harness into my 76 nova. Long story short I have all the wiring hooked up in the car, but I ordered a new OBD II connector because when I got the motor I found out they did not give me the port. I have the port hooked up correctly pin 2 to blue connect soldered to pin 58, pin 4 & 5 to ground, and pin 16 is battery hot side. I was trying to have the VATS turned off today and I get good power to the OBD II port, but it keeps saying communication error. I have checked my grounds...

(2) grounds from wiring harness to back of each head, (1) main strap ground from head to chassis, and there is another ground that is grounded to the side of the block near the power steering pump...I have checked each one individually and with a meter and they are all grounded properly...

Any ideas of what else it could be?

 

1 more ground from the back of the head to the battery negative

does the engine fire and then die like the typical one where vats hasn't been disconnected?

 

The vats has not been able to be disabled yet. They were trying to do that yesterday, but no success. I was told the car wont run without the vats disabled first??

 

It will crank/fire and briefly shutoff. I did that before my vats was disabled so I wouldn't waste my tuners time when he showed up. Do you have an LKQ nearby where you could pick up another computer for cheap? Could be the issue.

 

I just ran a 4 gauge wire from the negative side of the battery to the back of the drivers side head and no dice... Car turns over, but never fires...i do have an LKQ, but i was told it has to be either an 05-06 drive by wire car or 04 gto is that correct?

 

Being a Nova tell me about where you are pulling your cranking power from? On your fuse panel you have ACCSY BAT and IGN ... IGN will be the only one with 12v cranking for your swap harness power. If it turns over it should have briefly fired if you were getting spark.

I used an 03 tahoe motor and kept drive by wire. Green/Blue harness. Did you keep drive by wire? Any 03 - 06 Silverado, Tahoe, Yukon ecu should work.

04 GTO will not work for sure

 

I ran the red power wire (from original nova) out from the fire wall to the starter. I also ran the one from the new ls harness to the starter. I know the LS starter is probably not needed, but I didnt want to cut it or leave it hanging.

I also kept it drive by wire yes. Let me pull a plug and ground it to the head and see if im getting spark when it turns over.

 

Obviously the starter is wired ok... purple wire to your solenoid on the starter right?

I think your computer might be losing power when cranking...

 

I believe the purple wire is on it. I know I have a red to the starter itself and another wire to the solenoid that engages the Bendix on the starter. The hole motor turns over its its going to start, but it never fires up.

 

with the vats on it will only briefly fire, but it will... what is going on with your other harness wires? Your swap harness needs a 12v cranking source to the fuse block... is that coming off your stock Nova block spot marked IGN?

 

The purple wire is tied into a blue wire with a female type plastic spade... Here is the starter wired up...

 

I have a 1/0 gauge wire from the positive of the battery hooked to the oem power distribution block. From there its a 4 gauge wire hooked to the alternator, ls fuse block, and the starter all linking back to the oem power distribution block

 

The ls fuse block also needs a 12V cranking power source... was your harness a re work done by someone else or you?

Sounds like its missing and you aren't firing the coils because of it

 

No its the original harness. The LS fuse block does have power to it. I have a 4 gauge wire from the power distribution block to the fuse block.

 

This is just temporary wiring until i figure out where i want to mount everything, but you can see the power dist block feeding the fuse block.

 

The ls fuse blocks need 2 power sources - 1 12V key on cranking to fire the injectors etc

1 12V Bat source - typicall off the starter battery terminal

 

Alright I see now totally... you aren't getting power to your computer the way it is currently wired

http://lt1swap.com/2004vortec_pcm.htm

You need to get 12v cranking power into that stock ls fuse block

Look at that diagram

 

Found the information for you... here
Use this info to use the stock underhood fuse block. C2 is connection for engine wiring harness, other then that only 4 other connections needed, they are listed below:

C1- B11 - RED this wire feeds 12v Battery+ to ignition switch, hot at all times.

C1 - A9 - PINK - this wire is FROM ignition switch, hot in RUN, START. This powers up fuses on block.

C3 - F1 - GRAY - Power feed to fuel pump.

http://lt1swap.com/underhoodfuseblock.htm

 

I have power from the dist block to the bottom post...are you saying i need to run another wire from the dist block to the top fuse block post too?

 

yes C1 A9 as pictured