ECU Connector J1 Pin B17 / 2009 Cobalt 2.2L NA 5 Speed

[Doug Rostad]

What does Pin B17 on Connector J1 pin B17 red with white stripe wire trigger? The 10 amp fuse on the BCM in location 25 "ECU" fuse , would blow every time I connected the battery.
To eliminate as much as I can, I started disconnecting plugs one by one, add B+ Pop goes the # 25 10 amp fuse,, at this point I do not have any of the engine wiring connections. It still blows the 10 amp fuse in location 25. With the square gray plug on the main fuse box un mounted from the fuse box. Now ,,,,, with B+ power connected , I have power from BCM Rectangular Red connector D4 to Gray main fuse box plug connection E4....Fuse in position 25 on the BCM good .. On the square gray plug,, now out of the fuse box,,,, I take a wire and jumper E4 to E3 Bam! fuse blows!
So, , ,with my meter,,, I clip one wire to ground and the other lead touched to pin E3 on the gray plug. I have a direct connection to ground!
Before asked, I have 4 ECU's all part number 126.0186 ,, 4 BCM's all part number 25928052 , 3 fuse boxes. Every test with the same results.
What does Pin B17 on Connector J1 pin B17 red with white stripe wire trigger? I seem to have all of the schematics this forum has to offer. None , show what pin B17 BATT POS VOL Triggers ?

Does anyone KNOW what it triggers ?

 

[Gtstorey]

You have your number/letter system screwed up. “X’s are the letter/number of the connectors on the ECM, BCM, and fuse box connectors. Tell me which connector, what it is connected to and the PIN number and I’ll check the service manual.

 

[Gtstorey]

I see, you made up your own wiring designation. Circuit 840 is a power feed to the ECM on the manual cars.

 

[ToothMagician]

Circut 840, hope this helps

 

[Doug Rostad]

I see, you made up your own wiring designation. Circuit 840 is a power feed to the ECM on the manual cars.

Correct. My diagram as yours , Circuit 840 ECM Red & White wire (X1 20 LAP) B+ voltage.

What would cause it to be direct to ground?

 

[Ross]

Correct. My diagram as yours , Circuit 840 ECM Red & White wire (X1 20 LAP) B+ voltage.

What would cause it to be direct to ground?

What would cause an electrical short? There is so many answers...
A bad wiring harness.
A wiring harness installed wrong, with a Red & White wire connected to a ground post.
A Red & White wire that has worn away its insulation, and is contacting the frame.
A Red & White wire that has worn away its insulation, and is contacting another wire.
A bad ECM.

 

[Gtstorey]

Does it shoot a fuse with ECM disconnected?

 

[Doug Rostad]

Does it shoot a fuse with ECM disconnected?

No it does not. As soon as I put the J1 Plug in the ECM it blows the fuse in the BCM. that's why I started eliminating anything relating to the ECM. I have the complete wiring harness un-taped. including the engine harness. It isn't even run through the car at this point just the BCM Laying on the pass floor, the wires running over the roll bar to the fuse box laying on the plastic mount. the engine harness completely eliminated. The only things plugged in are the (turn signal and lights .. that work with no problems) the ignition switch plugs, the throttle plug, the BCM plugs are all in. The two ECM Latching plugs are in. The only piece of the fuse box not connected is the black / gray square plug for the fuse box. That is where I jumper the red and white wire from the BCM to the red and white wire going to the ECM , and it blows the fuse. That is when I used my ohmmeter and tested the wire going to the ECM , It is direct to ground. There only a couple wires on that plug that have been eliminated.

 

[Gtstorey]

And just to be sure, this isn’t an auto to manual swap?

 

[Doug Rostad]

And just to be sure, this isn’t an auto to manual swap?

Nope , The original manual transmission.

#3 BCM was in the car when I took these pictures last night

 

[Gtstorey]

This is not a bcm problem, it's an ECM problem either internally or downstream if it shoots the fuse only when the ECM is plugged in. And if it's multiple ECM it's probably downstream. And I don't know how to figure out what downstream may cause the issue.

 

[Ross]

Wow, you have 4 ECM and 4 BCM an 3 fuse boxes!!!
You have spent a bunch of money trying to figure this out.
How about we do a video visit, and see if we can get to the bottom of this?

That BCM fuse supplies power to circuit 840, which has the ECM an possible a TCM which isn't in this goblin, so just the ECM.
There isn't anything downstream, according to post #3 wiring diagram, and according to this wiring diagram.
Lets use an electrical meter to find the issue.
In order to pop a 10A fuse, you need a connection to ground with 12V/10A =< 1.2 Ohms resistance.

If you put your electrical meter on resistance, and one probe on the ECM ground (I'm guessing the aluminum ECM case is ground), and the other probe on the ECM X1 connector, pin 20, does it measure < 1.2 Ohms?

If so, Then
that ECM is bad, and will continue to blow fuses.
Otherwise,
Maybe the ECM is getting ground from some other wire?
We need to keep probing electrical circuit 840 to find where the short is.

 

[Gtstorey]

I wouldn't count on the aluminum case as grounded, but it might be. In practice, it would typically be isolated. I would check it to the individual ground pins in addition to the case.

 

[Gtstorey]

I probably did count out bad ECM a little too quickly. It’s very possible that a wiring problem on the ECM could have caused the same thing to happen to multiple ECM’s as soon as you plugged them or powered it up.

 

[Joebob]

If you are popping fuses across multiple ECMs and BCMs, it is not the computer but the wiring. I would pull off all the connectors off the computers and meter the pins to ground to determine which ones are grounding out and those that do, make sure they are only authorized grounds. Be careful with the pin receptacles in the plugs because if you stretch them, you will be chasing a whole 'nother problem later.

Joe

 

[Doug Rostad]

I wouldn't count on the aluminum case as grounded, but it might be. In practice, it would typically be isolated. I would check it to the individual ground pins in addition to the case.

I have checked the case of the ECM to ground,,,, found it is not grounded,,,,, thought , ok , I ran a solid ground wire to ground,,,,,,,,,, to no avail .

 

[Doug Rostad]

If you are popping fuses across multiple ECMs and BCMs, it is not the computer but the wiring. I would pull off all the connectors off the computers and meter the pins to ground to determine which ones are grounding out and those that do, make sure they are only authorized grounds. Be careful with the pin receptacles in the plugs because if you stretch them, you will be chasing a whole 'nother problem later.

Joe

Joe

I will test the connectors to ground, tonight, I have been so frustrated with this , The engine ran fine in the Cobalt and There are so few wires in this situation that were even eliminated. As I remember , in this ECM there were only a couple wires that were eliminated, and they were for the fuel pump / evap.
No wires are bare , or grounding out , externally. I have the complete harness separated and in plane site. Any wire that was extended is clear to be connected to it's original connection.

 

[Doug Rostad]

Find the and isolate the ground cluster that burns the fuse. That will further isolate the false ground. Here's a wild idea. Pull that wire out of both connectors, and replace it with a (temporary) jumper wire. This will by pass a ground hidden in the harness.

I have this fuse block connector out of the fuse block, With the battery connected if I jumper "E3 to E4" with the ECM plugs connected the # 25 10 Amp fuse in the BCM blows

 

[Doug Rostad]

Wow, you have 4 ECM and 4 BCM an 3 fuse boxes!!!
You have spent a bunch of money trying to figure this out.
How about we do a video visit, and see if we can get to the bottom of this?

That BCM fuse supplies power to circuit 840, which has the ECM an possible a TCM which isn't in this goblin, so just the ECM.
There isn't anything downstream, according to post #3 wiring diagram, and according to this wiring diagram.
Lets use an electrical meter to find the issue.
In order to pop a 10A fuse, you need a connection to ground with 12V/10A =< 1.2 Ohms resistance.

If you put your electrical meter on resistance, and one probe on the ECM ground (I'm guessing the aluminum ECM case is ground), and the other probe on the ECM X1 connector, pin 20, does it measure < 1.2 Ohms?

If so, Then
that ECM is bad, and will continue to blow fuses.
Otherwise,
Maybe the ECM is getting ground from some other wire?
We need to keep probing electrical circuit 840 to find where the short is.

Ross
Yes , Ebay loves me! at first I thought, ok maybe I tightened the fuse box connectors to tight. I ordered on,,, It was going to be a few days longer than I was willing to wait to move foreword..... so I ordered another one closer to me. Once I got it I took my original one apart,,, checked the board, Nothing wrong with it. but, it was an interesting experience. Then, to eliminate anything I bought a BCM and an ECM to try to eliminate the issue. Still to have the original result. Now with every engine plug disconnected, Brake plug , clutch plug disconnected. to get to what I see to be connection "E4" in the black fuse block plug,,,, that is to be supplying B+ Power to the ECM from "E3" from the BCM to be a dead short to ground. That red and white wire is 12" long and in plain sight to not be bare and connected to ground.
I was so frustrated with it last night I spent my garage time fabricating front and rear bumpers for the car , instead.

 

[Gtstorey]

If you are popping fuses across multiple ECMs and BCMs, it is not the computer but the wiring. I would pull off all the connectors off the computers and meter the pins to ground to determine which ones are grounding out and those that do, make sure they are only authorized grounds. Be careful with the pin receptacles in the plugs because if you stretch them, you will be chasing a whole 'nother problem later.

Joe

If it's popping a fuse when the ECM is plugged in but not popping with it unplugged, it gets a lot harder to point it to wiring upstream of the ECM. Not 100% impossible it's in the connector. Has this connector ever been apart?