Erratic cranking, no start

[samjesse]

Hello

I have 2006 VE V6.
It often does not crank when key on Start, sometimes it will crank but not long enough for the engine to run "split of a second".
P0615 is present but battery is new, terminals clean and even jumper to a brand new batter in parallel to make sure voltage is not low, I tried to switch the relays over, for no avail.
I applied B+ to control circuit of the relay and it keeps cranking as long as I give it B+.
What controls how long the cranking time is? Is it how long the key is held on Start position or the ECU based on what it gets from the BCM?
I back probed the pink wire on the back of the ignition switch, B+ when cranking/acc.
System voltage while cranking does not drop below 9.2v
It starts when the ECU sends the voltage for 900ms or so but some times it cuts off after 600ms or even 200ms "milliseconds"
Does any one have a wiring diagram or circuit design in order to understand and fix this problem please?

many thx

 

[Muke]

Yeah, I'm pretty sure it's the ECU that controls the cranking time. (I've slipped and just touched "start", but it continued cranking until start). However I would expect there to be a set max cranking time, or else it'd just keep going and going if the battery was too low which doesn't happen. eg. low voltage batt, you can try & try before giving up & jump starting - it doesn't crank until batt dead. I'm assuming you've cleared the error code and it came back? Might be a tech2 fix. Anyway, I don't have a VE diagram, but I do have a G8 wiring diagram. Not sure if it's the same as they have the remote start (though I wonder if that's just something that can be enabled rather than a different ignition system). PM me your email and I can send it to you if you still want it.

Good luck.

 

[RiCeY]

 

[samjesse]

Thank a lot for all the help. a 1.5v drop "during cranking" from block to chassis which I am fixing now. I will WD40 few times till crack the nut and fix and try again. many thx