V1 Anti-Theft

[KingChuck24]

Looks like I am back to my original question, how should I poke the wires coming out of the bcm and fuse box multiplugs if they are plugged in when the car is turned on?

 

[Rttoys]

Open up a paper clip and poke it into the back of the terminal (Not forcefully). attach your meter to the paper clip.

 

[Ross]

I have used pins to poke thru the wire insulation, touching the copper .

 

[KingChuck24]

Ok so I just started testing with the key turned to the right but not on start and on the bcm connectors I am getting .02 volts on them. Do I have to have the key all of the way to the right where it is cranking to get a test done?

 

[Ross]

The run/crank wires should have 12V+ when the key is in the run position and in the crank position.
So you have found an issue - no power at the BCM connector.

 

[KingChuck24]

Yay! Ok, not really sure how to fix that, is that a bad connection with power to the bcm or what? What should I be testing for?
Edit: The dash pins were also reading .02 volts
Edit 2: The power to that multiplug in the corner is getting 12 volts

 

[Ross]

The pink wires are suppose to have 12V+ when the key is in position 1 (run) and position 2 (start), but drop to 0V when the key is off.
Seems like all the pink wires at the BCM are this way.
The red wires are 12V+ no matter what position the key is in... basically to battery power, probably thru a fuse and maybe a relay.

You need to trace the BCM C3 pin D6 wire to see where it goes. Do you have a wiring diagram for your LT Cobalt? Or are you using my 06 LSJ AllDataDIY wiring diagram? Maybe a popped fuse, bad relay, or poor wire connection.

 

[KingChuck24]

I am using your AllDataDIY currently but I am finding it hard to navigate, what section should I be looking under. I tried going to the starter section but I am not having much luck. Thank you for allowing the forum to use your subscription it is a major help when doing things like this!

 

[KingChuck24]

I know that it is circuit 739 just not sure where to find other stuff in that circuit.

 

[Ross]

I was able to trace the BCM C3, D6 wire for my LSJ.

The grey box shows where it is on AllDataDIY.
Need to check your run/crank relay, and IP IGN 20A fuse.

 

[KingChuck24]

Got it, fuse is good but no volts going through it. Don’t know how to test relay but I tried testing continuity between all of the pins on the bottom and got nothing. Does this mean it’s bad?

 

[Ross]

The big 12V+ wire from the battery goes to the starter, then another medium wire goes from there to the fusebox in the rear.
Do you have 12V+ at the rear post in your fusebox?
From there it goes to the run/crank relay. Pull that relay, check for 12V+. Is it there?
After that it gets to the 20A IGN fuse. With the fuse in place, can you probe the top of the fuse for 12V+, on both sides?

 

[KingChuck24]

I will check that tomorrow but based on what you have said about the relay going to the fuse and the fuse being good but it not getting 12 volts I am assuming it is the relay. Thanks again for all this help, I know it takes a lot of time but I really appreciate it!

 

[Goblinfanclub1234]

you can swap the crank relay with another relay in the fuse box that is the name part number and see if the problem changes.

 

[Rttoys]

you can swap the crank relay with another relay in the fuse box that is the name part number and see if the problem changes.

correct. There’s a lot of those relays we don’t use anymore when we swap from the cobalt to goblin, so there are plenty of spares in the fuse box. The down side is, those relays rarely go bad.

 

[Rttoys]

here’s another helpful tip.

On the back of the fuses there’s 2 “dots”, I circled in yellow in the pic. These are your test spots to truly know if a fuse is good. A test light make this process a lot faster and in a case like yours an older incondesent bulb test light is better. A led test light will active with almost any voltage, but an old school bulb will need the full 12v to turn on or will be dim with anything less than 12v.

with the fuses installed, ground your test light (or meter) and touch one side of the fuse, then the other. They will both be hot or both be cold, depending if the circuit is on. If one side is hot and the other is not, then the fuse is blown.

 

[KingChuck24]

Tested the voltage on the run/crank relay and here's what I got. I went off the numbers on the side of the relay that showed the circuit diagram:

Sorry about the picture but bottom left is 30 top left is 86 bottom right is 87 and top right is 85

Those corrispond to the pins that I tested on the fuse block
86-30: 12 volts
85-87: 4.2 volts

both 85-86 and 87-30: no volts

When I was poking the 85 and 87 with my multimeter set to 12 volts it would start making the clicking noise, not sure if thats normal.

Tested fuse and its good, I swapped it with another 20 amp fuse just to make sure it same issue occured, fuse gets 0 Volts but I assume its part of the relay instead. I also swapped a different relay in and the same issue occured. Does this mean its something in the actual wiring, maybe a loose connector from the relay circuit?

 

[Ross]

Interesting. Did it fix itself? Does your BCM all of a sudden have 12V+ on connector C3, pin D6? (With the key on, and relay & fuse installed)
This RUN/CRNK relay should click when the key turns, which sends power to this IGN fuse. If you use Russel's testing proceedure (Rttoys above),
the fuse has 12V+ on both of sides of this IGN fuse?

There is 12V+ power to the relay on pin 30? That verifies that power is getting to the rear fuse box.

as viewed from the fuse box. This image has the pins oriented correctly.

 

[KingChuck24]

Tested power to bcm c3 b6 pin and still nothing. Tested power to pin 30 on crank relay and it read good. I haven't been able to test voltages while the car is cranking as I need a second person to turn the key while I hold the multi-meter but I have a firend coming over later today so I will be able to test that. One thing I have been noticing is my battery has been dying extremely quickly, I leave been leaving the positive and negative terminals connected these last couple of days and almost every day it drops to around 11.7 volts before I then charge it to 12.6 again, but the thing is I tried using a jump pack (that red box I have, turned it to the jump options) and it still isn't working (tested the voltage coming from the jump and its around 12.6). Not really sure where to go from here, do you think it could be some wires that are burnt up or something of that sort?

 

[Ross]

The BCM C3 B6 pin should be 12V+ when the key is in the run position. Also when the key is in crank position. So just test it by yourself with the key in run position... don't worry about crank position.

We need to find why the 12V+ isn't getting from pin 30 on the run/crank relay to the BCM C3 B6.
We are close to finding the problem. Next test:
- Put the relay back in, turn the key on (run position), then test the top of the IP/IGN fuse for 12V+.

I would disconnect your battery when you aren't using it. We can look for vampire electrical loads later... one problem at a time.