08 Envoy No Crank

08 w 133k 4.2L SLT. I recently had replaced the ignition switch and P/N switch in the console for another issue. During the other issues it would not crank every time when keyed and now won't crank at all. I had assumed the intermittent crank had to do with not recognizing P/N position and not releasing my key. But after the console switch was replaced the key turns to off and can be removed but the starting issue remained. So I removed the starter and it tested good. I have 12v at the post on the solenoid but there is no voltage to the solenoid lead when the key is in start position (she turned the key). I swapped the relay and no change. I am starting to wonder if the BCM is passing the signal to the relay. How would I follow this back to the problem? Do the BCMs fail often?

A BCM can fail, but there are other things in the circuit as well, including the harness and connectors. Get the schematic and start working your way outward from the ignition switch, then from the BCM to the relay, and beyond if necessary.

I just helped my brother diagnose a no start on his Equinox. He had torn the dash apart to do the heater core. BTW EFFFFFF GM and the dumbass engineers that decided to design it that way.

Anyway, after assembly he tried to start and had radio, dash lights, etc, but no crank. He called me for help, because I seem to have to play hero anytime he gets into something. LOL He is in the car messing with it as I pull in the driveway and first thing I noticed was the reverse lights were on.

At first I dismissed it as courtesy lights. I tried a few tricks I have learned over the years and got nothing. Finally I decided to jump the starter relay. I touched it just enough to see if I got anything, and it cranked. I put the ignition into the run position, and had him sit in the drivers seat and hold the brake just in case.

I jumped it over again and it fired right up. That's when he realized even though the shifter said it was in park, it was in reverse. That explains the reverse lights I noticed.

After a little digging he realized that somehow the cable had popped off the shifter upon reassembly. He tore it back apart enough to pop it back on and after that he was able to start it with the key.

So, I've rambled on, but I was hoping to point some things out to you along the way.

#1 Try moving the shifter to neutral and see if it starts there.

If it does not then you can try #2 Remove the stater relay and use a piece of wire to jump across and see if it cranks. BE VERY CAREFUL if you do this. Have a second person in the car behind the wheel just in case it is in gear.

If it does start after trying that then you need to start diagnosing why it won't start like normal. I have had older vehicles that I sometimes had to "slam" into park, because I would have the same issue. Come out to leave and it won't start. It got to the point where I just pulled the shifter into neutral to start until I got the cable adjusted better.

Either way, good luck.

Update: watched a youtube and checked voltage in the starter relay spade holes, The two legs had 12v and the ground leg also read when reversed. I jumped across two legs and the starter engages. So electrically from the fuse box to the starter is good. So the BCM is not passing the signal for some reason. (we were driving this after the key issue but the intermittent start continued so I don't think the cable slipped) So what switches have to be made for the BCM to send out a signal. I know of ignition, P/N switch but I don't have access to schematics so youtubing and asking questions on here. Thanks for the response.

Maybe:

http://wiringdiagramsdraw.info/wp-content/uploads/2018/04/new-of-wiring-diagram-for-a-2008-equinox-crank-relay-and-starter-1963-chevy-impala-diagrams-thermostats-carrier.jpg

Looking at the wiring diagram, I would check to see if the PCM(crank) fuse is ok, and getting power with the key in the crank position....if it isn't could be the ignition switch/wiring.....

If it is, then I would take a jumper and attach it to the C10 spade of the crank relay... ...re-insert relay...turn key just to "on" position....now ground that jumper......if car cranks over, the PCM is not grounding the relay or you have an open wire or you have a bad connection in the UBEC(your relay center....make sure the 3 silver bolts in the center are tight) or the BCM is not sending a crank enab le signal to the PCM....one possibility is you have a Security problem, and the PassLock sensor is not sending a good signal to the BCM, or the BCM is bad.....

To diagnose this, you would need a scan tool, like the GM Tech II, to see if the BCM is get a good signal from the Passlock sensor, and if it is sending a starter enable signal to the PCM....