V1 Cobalt related No-Crank

[Gtstorey]

That might cause a problem. Has that been hot or just corroded?

 

[Trail_Creeper]

Just corroded. Unfortunately it didn't help my issues at all. Relay is getting power but no signal to turn on.

 

[Gtstorey]

And you have checked for continuity from on of the relay connections to the starter solenoid?

And you have 12v on two of the relay connections?

 

[Gtstorey]

And you do realize the signal for that relay to cut on is ground through the BCM not a +voltage?

 

[Trail_Creeper]

I'm getting 12v here:

And have a good ground through G101 at the top right

 

[Gtstorey]

We are still talking about the powertrain relay? Looking at the diagram you posted you should have 2x12v terminals which you do. You will then have a switched ground that will close the relay when the switch is on. You will also have the load side terminal. which will feed several fuses including the injectors and PCM. If that terminal is grounded when switching the car on, it's should be the signal side and the relay should close. If it's the load side that is grounded then you have more problems either in the circuit board or in the wiring. Can you hear the relay click when plugging it in?

Don't make the mistake of thinking that all of these relays in the cobalt/goblin get a 12v+ signal to close the relay and have a full time ground. Some are this way but many (I think most but haven't counted) are full time 12+ and have a ground signal to close.

 

[Trail_Creeper]

The relay in that spot won't click at all. If I swap it to another spot (run/crank) it will click. That goes the same for the fuel pump relay.

Bot of then share the same G101 ground and look to be on the same BUS path according to the diagrams.

I think, and could be wrong, this is why I have no power downstream of these 2 relays. Looking back at @Ross power issues he had a while back mine are pretty similar. But from what I can gather the BCM under the dash is fine.

 

[Gtstorey]

I still don't see anything on your diagrams that say that the powertrain relay should be grounded to a permanent ground, G101. Am I missing it?

 

[Keckster]

is your security light on by chance?

 

[Gtstorey]

If you checked for ground by using the tone for continuity check on a multimeter, I'm thinking your "ground G101" may be the load side of the relay finding a path to ground either through one of the sub relays or through the injectors/coils. There should be a measurable resistance if that is the case, but it will still show continuity to ground.

See if you have Continuity to one of the fuses shown on that circuit from terminal labeled G101.

 

[Trail_Creeper]

is your security light on by chance?

Just during the initial key on light check

 

[Gtstorey]

I checked a spare relay and the pin that you are saying is grounded is on the load side of the relay.

 

[Gtstorey]

Pins 87 and 30 are the load side of the relay. Remember you are looking at the bottom of the relay and have to flip it over to match up the pins. So you are either getting ground through the various loads on the relay or have something shorted to ground. I would guess the former. Now you need to figure out why you aren’t getting a ground signal on the remaining terminal when the key is in the run position. The later models get this ground from the ECM but you need to find the correct diagram for your model to see what yours does. Since this started after you messed with the fuse box, my money is still on a loose individual terminal on the fuse box plug.
You can still call me if you want to discuss.

 

[D&dgoblin69]

Did you say you installed a junkyard ecm? Usually ecm is programmed to vehicle but can’t be swapped between other vehicles. Can you go into ecm and see what vin is burned into it? It has to match the vin of your car.

 

[Gtstorey]

He was running until he moved some wiring is what I read and he replaced the ECM/fuse mounting bracket/holder.

 

[Ross]

Did you say you installed a junkyard ecm? Usually ecm is programmed to vehicle but can’t be swapped between other vehicles. Can you go into ecm and see what vin is burned into it? It has to match the vin of your car.

I think that is true on an LNF, but not the LSJ cars.

 

[Trail_Creeper]

I appreciate the assistance everyone. The Girlfriend had some family stuff come up so I've had to put the cobalt on the back burner for the last couple weeks. Unfortunately it will be a week or two until I can get back into figuring this out. Once I jump back in it I will definitely reach out to you all for any questions that may come up.

Thanks again, everyone!

 

[Trail_Creeper]

***Update***

Well after all the testing wires, swapping fuses, and trying to sort out the issue with this car... I decided to throw an ECM at it. Ordered from eBay and it arrived yesterday. After the relearn process the car fired right up.

Thanks again @Gtstorey @Ross and everyone else that reached out to assist.

 

[Gtstorey]

I would hold on to your old ECM. There is a decent chance that you "fixed" a loose connection somewhere in the process of swapping out the ECM. But it's not impossible you had a bad connection in the ECM that was disturbed when you swapped out the holder.

 

[Trail_Creeper]

That's the plan. I'm going to hang on to the old one and once the wiring is all done for the Goblin and that's running, I may throw it in to see if it goes back to what it was doing before