Ls3 swap, no spark, no injector pulse.

[fishface]

Hi folks, was hoping to fire up my ls3. I have fuel pressure, but no spark or pulse​. This is in my 69 Camaro with AAW Classic Update harness. I used the following for my three wire hookup to the engine harness from the AAW accessories connector: dark blue fuel to gray fuel power feed on harness, orange BAT1 to orange constant power, and pink IGN1 to pink ignition on harness( this also says for cruise control or other ignition circuit. AAW says this should be hot in crank and run. Checked crank and cam sensor connection as well as grounds. Engine harness is grounded to back of drivers side head. I'm stumped! Lol. Anyone have an idea? Also forgot to add that ecu has had vats turned off.

[csouth]

Sounds like you say its turning over but not firing? What engine harness are you using? I have AAW body harness, but my constant power for the engine was to the hot side of the starter. My other wires are the same, grey ls harness to blue aaw for fuel pump and pink/blk ls to pink ignition on aaw for cranking. Sounds like you're wired correctly. Only thing I would have done different was use the ignition wire that was intended to go to the distributor, but that's no biggie. Your LS harness should have an ECM/Batt fuse, have you checked that?

[fishface]

Hi Chris, thanks for the response. That is correct, cranking but bot starting. The harness is a Modern Vintage, I have a relay for the fuel pump but no fuse for ecm that I am aware of.

[csouth]

Hi Chris, thanks for the response. That is correct, cranking but bot starting. The harness is a Modern Vintage, I have a relay for the fuel pump but no fuse for ecm that I am aware of.

You have a picture of the LS harness fuse panel? There sould be a fuse there for the fuel pump along with a relay. I'll show you what my old Currrent Performance harness had. You may not have all this, but def need coils, ecm and fuel. Mine has AC and fans.

https://static1.pt-content.com/images/pt/2017/06/IMG_6565_zpsomitwph6-1.jpg (http://s897.photobucket.com/user/csouth89/media/IMG_6565_zpsomitwph6.jpg.html)

[fishface]

Hi, mine didn't come with a fuse panel. It has the power feed wires the only the fuel pump relay. The fans are through an Entropy controller and the ac is through a Classic Auto Air control.

[andrewb70]

There are two large ground wires that go to the back of the heads (or there should be). Are they connected?

Andrew

[fishface]

Hi andrew, I only have one on my harness that I am aware of and have it running to the back of the drivers side head.

[csouth]

Hi, mine didn't come with a fuse panel. It has the power feed wires the only the fuel pump relay. The fans are through an Entropy controller and the ac is through a Classic Auto Air control.

I have yet to see one that didn't have any fuses and that's including factory harnesses that have been reworked...Unless its integrated with AAW? Not to say I've seen them all either...lol

[fishface]

I will check it out this morning hopefully. The humidity is a killer here so kind of limited to how long I can stand to be out there. I definitely appreciate the input and will let you know what I find out. Thanks guys!!

[Z06vet]

What ecm are you running? IF factory E38 or similar, be sure everything is disabled in the tune related to VATS, start enable/disable. If its a manual tune, disable the clutch switch as well.

[fishface]

Yes, it's an E38 which was said to be unlocked. Also had a mail order tune from Mike Norris on it so going to talk with him tomorrow and see if that is a possibility that something is not completely turned off with VATS.

[badazz81z28]

The car wound fire and then die if it was VATS, you have wiring issue. It's very common and usually the ECM power. I used the stock harness distributer wire to do that job. No guessing if it's hot while cranking. Battery power, grounds and you should be good to go if all other connectors are connected. There's not much to wiring these LS engines.

[csouth]

Hi folks, was hoping to fire up my ls3. I have fuel pressure, but no spark or pulse​. This is in my 69 Camaro with AAW Classic Update harness. I used the following for my three wire hookup to the engine harness from the AAW accessories connector: dark blue fuel to gray fuel power feed on harness, orange BAT1 to orange constant power, and pink IGN1 to pink ignition on harness( this also says for cruise control or other ignition circuit. AAW says this should be hot in crank and run. Checked crank and cam sensor connection as well as grounds. Engine harness is grounded to back of drivers side head. I'm stumped! Lol. Anyone have an idea? Also forgot to add that ecu has had vats turned off.


The car wound fire and then die if it was VATS, you have wiring issue. It's very common and usually the ECM power. I used the stock harness distributer wire to do that job. No guessing if it's hot while cranking. Battery power, grounds and you should be good to go if all other connectors are connected. There's not much to wiring these LS engines.

Rereading your original post, have you checked the fuse panel? As I and badazz81z28 posted, looks like your are losing power to your ECM. You said its wired to cruise/alternate ignition. I wired mine to the distributor ignition wire and so have others. The cruise is key on and run, but most likely its also fused circuit. I would use the wire intended for the distributer.

[fishface]

Thanks for the replies, I hope to get to work on it this weekend. I will try a different circuit. I went over my grounds and all connectors this week. Hopefully I will get it fired up and let you know.

[fishface]

Hi everyone, just an update, still no luck. I tried using distributor wire for ignition feed and verified hot in crank, bypassed everything by hooking ignition feed and constant 12v directly to the battery, took computer back out and verified VATS is turned off, and changed both cam and crank sensors, went over all grounds and made sure battery is fully charged. Needless to say I am getting discouraged. I'm at a loss for what to try next. Any ideas greatly appreciated.

[andrewb70]

I suspect something is wrong in your harness. Who made the harness? Where are you located?

Andrew

[dhutton]

I suspect something is wrong in your harness. Who made the harness? Where are you located?

Andrew

Modern Vintage Systems from above.

Don

[Z06vet]

Is the clutch switch turned off in the tune as well? It's in a different tab then the VATS (at least in HP tuners)Are yo, but I forget which one. Be sure everything start enable/disable is off. I had this issue the very first time I used an E38. Is the computer receiving a signal from the crank sensor while your trying to start it?

[badazz81z28]

Yeah, which harness you got? I have used GM and PSI, they had 3 grounds

[dhutton]

Yeah, which harness you got? I have used GM and PSI, they had 3 grounds

Modern Vintage Systems...

[fishface]

I will try to verify the crank signal. I have my daughter's wedding going on this weekend so not sure how far I will get but will let you know. . Thanks for all the replies, I'm confident it's something minor.

[12sec ss]

Something I haven't seen mentioned. Are injectors new or used? Used injectors depending on how long they've sat will lock up, happened to me before. Try some starting fluid, if it fires with starting fluid check injectors.

[12sec ss]

Hmm long day, didn't see that no injector pulse has been verified.

Besides having vats off, make sure starter check option has been disabled

[fishface]

Great news guys, I got it fired up this morning!!! I made a rookie mistake but hopefully this may help someone else down the road. I removed the small extension harness and bracket from the cam sensor last year to install my front accy drive, balancer etc. After being away from it for awhile I forgot to reinstall it and plugged my engine harness directly into sensor. Should have know something was up because harness plug wouldn't fit without removing small plastic keyway. Anyway, reinstalled and fired up first shot. Thanks everyone for all your help through this. It's been a serious learning experience but a rewarding one. I feel like I could do it again with a lot less problems.

[csouth]

Glad you got it figured out!

[andrewb70]

Great news guys, I got it fired up this morning!!! I made a rookie mistake but hopefully this may help someone else down the road. I removed the small extension harness and bracket from the cam sensor last year to install my front accy drive, balancer etc. After being away from it for awhile I forgot to reinstall it and plugged my engine harness directly into sensor. Should have know something was up because harness plug wouldn't fit without removing small plastic keyway. Anyway, reinstalled and fired up first shot. Thanks everyone for all your help through this. It's been a serious learning experience but a rewarding one. I feel like I could do it again with a lot less problems.

That little sub harness also swaps a couple of pins around (which is why you had no cam signal and it didn't start). Don't remember which ones exactly...The plugs are also different, as you discovered.

Andrew