Won't crank with key turn

[Painjack]

Hi everyone, I have been searching the forums for advice on this, and found quite a bit, unfortunately none of it has panned out for me yet. Here is the situation:

Donor was an 09 LS cobalt, automatic
Goblin is an A/T version

I have everything assembled minus the seats and the tail lights, and the darn thing won't crank when you turn the key. I can get it to crank just fine by jumping the relay in the fuse box with a paper clip, but with the key turn nothing much happens (a bunch of clicks and little whirrs behind me as relays go and I think the fuel pump primes). I have taken the fuse box apart twice to check for bent pins and or improperly seated multiplugs and found nothing there, and all the multiplugs are cranked down tight. I've checked the grounds all over the place and everything is good with an ohm meter. I've checked to make sure there is a ground coming out of the white multiplug in the fuse box, and there is and it is seated on the frame. I've checked for voltage from the battery at the starter, that is good (verified by screwdriver jump on the posts, and again with a paper clip in the relay). I've swapped relays with no success there either. I have double checked that the brake position sensor is connected, which it is, and checked for continuity through it to the battery, 2 of the three wires show small resistance to the black post on the battery and the middle one reads as an open line, I have done the same to the shifter connector, with the black wire there showing good connection to a ground lug. I'm pretty stumped! Anyone have any ideas for other things to check? The only lights that are on are a check engine light and the air bag light, and after a couple minutes with the key on the tire pressure light comes on (I do not have the tire pressure fob thing connected), I do have one plug that isn't connected to anything under the dash area, I'll include a couple pictures of it as I have no idea where it is supposed to go.

Please help!
Thanks!

 

[ATMironov]

Hi everyone, I have been searching the forums for advice on this, and found quite a bit, unfortunately none of it has panned out for me yet. Here is the situation:

Donor was an 09 LS cobalt, automatic
Goblin is an A/T version

I have everything assembled minus the seats and the tail lights, and the darn thing won't crank when you turn the key. I can get it to crank just fine by jumping the relay in the fuse box with a paper clip, but with the key turn nothing much happens (a bunch of clicks and little whirrs behind me as relays go and I think the fuel pump primes). I have taken the fuse box apart twice to check for bent pins and or improperly seated multiplugs and found nothing there, and all the multiplugs are cranked down tight. I've checked the grounds all over the place and everything is good with an ohm meter. I've checked to make sure there is a ground coming out of the white multiplug in the fuse box, and there is and it is seated on the frame. I've checked for voltage from the battery at the starter, that is good (verified by screwdriver jump on the posts, and again with a paper clip in the relay). I've swapped relays with no success there either. I have double checked that the brake position sensor is connected, which it is, and checked for continuity through it to the battery, 2 of the three wires show small resistance to the black post on the battery and the middle one reads as an open line, I have done the same to the shifter connector, with the black wire there showing good connection to a ground lug. I'm pretty stumped! Anyone have any ideas for other things to check? The only lights that are on are a check engine light and the air bag light, and after a couple minutes with the key on the tire pressure light comes on (I do not have the tire pressure fob thing connected), I do have one plug that isn't connected to anything under the dash area, I'll include a couple pictures of it as I have no idea where it is supposed to go.

Please help!
Thanks!

The connector should be for the TPMS module.

Try putting the shifter into neutral and see if that will get it to start

 

[ATMironov]

The connector should be for the TPMS module. If you have the module plug it in.

Try putting the shifter into neutral and see if that will get it to start

 

[Painjack]

Try putting the shifter into neutral and see if that will get it to start

Just saw your post so I ran out to the barn and tried that, no luck. I believe I still have the TPMS module somewhere in my hardware pile, I wasn't planning on using it since I got new wheels and tires that don't have pressure sensors in them, and as an off-road version it will frequently be running with very low tire pressure. I can plug it in though and see if that makes any difference.

 

[k.rollin]

That plug goes to the TPMS/keyless entry receiver; it shouldn't be causing your no crank condition.

 

[Ross]

Just put a start button on the dash. The engine doesn't run unless you have the key, right?

I had an issue with the starter not cranking because of a GMLAN data being intermittent.
I ran an extra wire so I could start it.
After I replaced my power steering unit, the intermittent LAN data issue was fixed... but lots of things can cause LAN data issues.

 

[MJP61]

Do you have access to a scanner that shows what gear the car is in? If the computer sees that the car is not in Park or Neutral, it won’t start.

 

[Painjack]

Just put a start button on the dash. The engine doesn't run unless you have the key, right?
View attachment 25690
I had an issue with the starter not cranking because of a GMLAN data being intermittent.
I ran an extra wire so I could start it.
After I replaced my power steering unit, the intermittent LAN data issue was fixed... but lots of things can cause LAN data issues.

I've spent all afternoon going back over everything again, and still no luck, so I am ready to embrace this solution to it. I spliced an extension wire to the starter solenoid and ran it through the channel to the dash, what hot wire do you recommend using to energize it? I tried the purple and pink striped wires that I had coiled up by the brake cylinder, but they don't have enough amperage in them to do the trick. I can go direct to the battery terminal, but that burns the wire as it is a lot of amperage for that little wire.

 

[Ross]

If you use the starter solenoid wire, it is fairly low amperage.... I used the 12v auxillary power jack (cigarette lighter) to energize the purple wire that went to the starter solenoid. The solenoid will throw the high amperage contacts that the starter motor needs.

It is the purple circled wire in this post.

 

[Painjack]

If you use the starter solenoid wire, it is fairly low amperage.... I used the 12v auxillary power jack (cigarette lighter) to energize the purple wire that went to the starter solenoid. The solenoid will throw the high amperage contacts that the starter motor needs.

It is the purple circled wire in this post.

Yep, that's the one I extended, the ones I have looked at so far for powering all only had .01 amps in them. What color is the aux power wire you used, and where do I find that one?

 

[Ross]

On my 06 SC LSJ donor car, there is a 15A lighter fuse for the aux power, and a 20A trunk outlet fuse in the fuse box for the second aux power cig lighter jack.
My signature line has a link that will show you how to set up your signature line to list your donor car.

AllDataDIY Login for my donor car... has electrical diagrams.
Fusebox diagrams here.

 

[Dale E]

Two things:

When you turn the key to the start position what wire/terminal sends power to the purple wire at the starter? Trace that wire to the BCM/ECM fuse.
Good fuse - great! Power from fuse to starter? Great! If not is fuse blown?

At the starter relay in the engine fuse box, you say if you jump it it will start? Good. There should be a small 10 or 15 amp fuse next to the relay (possibly marked IGN?) Is that fuse good? If not replace. Now, on the ground side/lug of the starter relay, run a jumper wire to a known good ground. Try key start. If it starts, trace that ground lug in fuse box to connection plug to grounding source on frame or engine. Replace or clean/rebuild broken ground wire. Or if it started with the key with the relay ground lug jumped then simply run a new ground wire.

Ground for the starter relay should be on the back of the engine or where ever you mounted that bundle of ground wires to the frame/engine during assembly.

Somewhere in the multiple pages of this same historical event in ARD-D build and just a few weeks ago another person had this event. Both were solved by a ground wire issue.

Dale

 

[Ross]

Putting the start engine button on the dash will bypass the ECM, so it won't check if the clutch pedal is pressed.
The purple wire goes to the starter solenoid. The key start signal is a white wire that goes to the BCM. I am guessing the ECM is the one that checks the clutch is pressed in before sending the signal to the starter.

Both aux power fuses are in the fusebox.... I was wrong about the BCM having one.

 

[Painjack]

well I have spent most of today and yesterday working this, with little actual progress. Here is an update as to what I have tried:

Removed all grounds from the frame under the fuse box, polished the mounting post and ground lugs, remounted and tightened down
Removed the ground lug from the transfer case, polished the lug and post, and remounted that.
Checked all fuses related to crank or ignition in the fuse box

None of that fixed the cranking issue, so then I spliced a new wire into the purple starter solenoid signal wire, and ran it up through the channel to the front of the car (the wire still extends to the crank relay, this is an additional leg), then I pulled apart the BCM, removed the large white multiplug off the back of it and added a heavy-ish gage wire to it to contact an unoccupied Ignition Voltage pin, and ran that wire up to the dash area. I've got a momentary switch on order to wire these too. Now if I contact the new wire from the BCM to the purple extension wire (while the key is in the run position), the engine cranks happily, but it never actually starts. Over the course of all this I left the **** key in the "accessory" position over night, so the battery is dead. I have it on a charger now, and the battery wasn't in great shape to start with (donor sat on a salvage lot for several months over the winter, in Michigan), so I am going to try to get it to start up again after it has reach full charge, but I'm not holding my breath about it. I'm guessing the next steps will be to check the fuel pump and spark plugs, anyone have suggestions for fast and easy way test the fuel pump? I can use a spark plug light to check if I am getting spark I know.

 

[Lonny]

I think the engine not turning over and the engine not starting when you jump the relay are clues.
I would look for data wire problems. Low speed and high speed.

 

[Painjack]

I think the engine not turning over and the engine not starting when you jump the relay are clues.
I would look for data wire problems. Low speed and high speed.

ok, that is something I have not looked into at all. How and where do I check that out? I just did a quick search of the forum and it didn't turn up much.

 

[Ross]

If you can pull the OBDII codes from that port, it is a pretty good test of your GMLAN.
If it doesn't work you can start tracing down the issue.

 

[Painjack]

So i've done some digging, and watched a couple good videos that Dave E sent me, and i've figured out that i don't have a good ground on the 85 pin under the crank relay. From looking through the diagrams on alldata, I see this:

But I am so far unable to find a diagram that shows me which multi plug is X1, and which pin is B12, to further trace the fault. Can anyone point me in the right direction?

 

[Ross]

Well my 2006 Cobalt on AllDataDIY didn't have an X1, but did have Fuse Block C1 with
connector B10 as the purple wire that goes to the starter solenoid. (Wow your diagram has a 30A fuse on it... and I was running that on a 15A circuit!)
Try searching "Fuse Block" in your AllDataDIY.

 

[MJP61]

The Black/White wire (85) should go to a ground. Probably the same ground lug as the Black/White wire from the Neutral Safety Switch. I think it goes to the Transmission stud.