1968 C10 5.3L LMG no start?????

[tk-mpl]

Hey guys, have been a lurker for quiet a while but now need some help.

I am building a 68 chevy c10 with a 2007 5.3L/4L60 powertrain. Everything is in and wired up. It turns over but does not start. I have no spark and no noid. At a lose right now and could use some help. I have EFI Live for the tuning, but a friend of mine does the tuning. We turned off the Vats, but still no noid or spark...
Trevor

[joecar]

Trevor, welcome to the forum...

Check if you're getting a CKP signal (does RPM show a value on the scantool while cranking)...?

[GAMEOVER]

http://forum.efilive.com/showthread....ight=E38+start
http://forum.efilive.com/showthread.php?t=10888

[tk-mpl]

I have a crank signal, you can see it on efi scan tool. The only thing I really have to go on is a p0615 and p0690...

[tk-mpl]

I have seen alot of people say that vats won't let it crank. I don't know if this is right but on my truck the bcm relays the start request through GM LAN network. I don't have a BCM so I just wired the starter relay enable right to the crank circuit off of the ign. switch. I don't know how to show the PCM a starter request to be able to use the pcm to enable the starter relay.

Trevor.

still no spark and no noid?????

[ChipsByAl]

You should still have a spark output. What kind of harness are you using? Is it a factory harness that is modified or an aftermarket one? For a quick check, unplug one of your coil/modules and test for grounds at terminals "A"& "B". Then check for 12 volts power on terminal "D" with the key on and during cranking.
Al

[tk-mpl]

It is a modified , by me, stock harness. I do have power and ground with key on and power while cranking. How do I test the out put from the pcm??

[GMPX]

2 or 3 should work, either one sends the ECM down the right path.

I thought even with the VATS still active, the engine will fire briefly, like 1/4 of a second just to let you know, yes everything is ok but I am not going to allow this engine to keep running.
I also thought the request to crank was a discrete input not a GMLAN message (I think the discrete input is J1-52, but I don't know that is 100% correct). I confess, that is beyond where I normally deal with so I am not sure. The ECM does seem to get grumpy when the starter relay output is left open circuit (J1-67).
Maybe post up your file too.

[tk-mpl]

there is got to be a way to tell the pcm to start other then the GM LAN message from the bcm...... Is this PCM in an older vehicle that may not need a GM LAN message and has like a 12 volt input to the pcm to start...

Trevor

[gmh308]

2 or 3 should work, either one sends the ECM down the right path.

I thought even with the VATS still active, the engine will fire briefly, like 1/4 of a second just to let you know, yes everything is ok but I am not going to allow this engine to keep running.
I also thought the request to crank was a discrete input not a GMLAN message (I think the discrete input is J1-52, but I don't know that is 100% correct). I confess, that is beyond where I normally deal with so I am not sure. The ECM does seem to get grumpy when the starter relay output is left open circuit (J1-67).
Maybe post up your file too.

Just for fun some OS's use J1-67, others J1-52. Seems J1-67 is earlier, J1-52 later. Vegasrobbi has had success with a resistor in circuit so it looks like it expects to see some idle current to ground.

And to make it just a little more perplexing even some OS's that use this J1-52 crank relay control will start on the second crank and some wont.

Will give it a shot this morning and report back.

Unfortunately the request to crank is generated via the BCM which the ign switch connects to. There are no wired inputs in relation to this so can only assume it is one of those functions like cruise control that has disappeared into the mysteries of the GMLAN.