Cooling fans troubleshooting help, please!

[kpeters59]

Hey all!

I have a 2012 SS that the cooling fans don't seem to turn on as commanded every time.

I've been fussing with this for a bit and only recently learned that I can command them on with my MPVI3.

When I do that, it turns them on sometimes. Most times, really.

But, there has been multiple times when I command 'Fan 1' on, which is 'Low Speed' for both fans, they either won't turn on at all, or they might kick on briefly, but then shut off.

This also happens, usually at the same time, that Fan 2, which IIRC, is the Drivers Side Fan and Fan 3 also don't go in to high speed.

When it's working, if I only command Fan 3 on it will go to High Speed and Fan 2 will go on if I command Fan1&2 together.

During this mornings poking around, I did notice that Fan 1 did seem to respond to some gentle wiggling, which surprised me because I'd tried that multiple time previously without seeing that. Because Fan 3 ought to be able to work in High Speed regardless of Fans 1&2.

I pried the covers off of the relays and while manually pressing the relay all 3 modes work every single time.

I visually inspected the relay sockets and the fan 4-pin plug. They look very good.

I'd guess that I need to locate some 'test points' for the harness wiring.

Can anybody help me figure out how to determine which pin on which plug at the PCM and the fuse block I might be able to get to to manually test at?

I do have a fake Power Probe that I ought to be able to inject the correct signal to the circuit. It looks to me like the PCM pulls the relay coils to Ground, right?

Anyway, sorry for the long post, but I figured we could skip ahead a bit if I posted what I'd already tried from a few other threads on this forum.

TIA,

-KP

[gtstorey]

You can get full wiring diagrams from;

https://www.acdelcotds.com/subscriptions

[gtstorey]

And you sometimes have to be careful using HPT's commanded stuff. It occasionally doesn't behave like you think it should. I don't know if this is one of those cases.

[gtstorey]

Originally Posted by kpeters59

Thanks for replying!

I seem to have wiring diagrams, but it's unclear which plug on the PCM and Fuse Block is which.

[IMG]file:///E:/Downloads/attachment[1].php.jpg[/IMG]

Attachment doesn't show but the ecm connection location diagram and pin out should be available at the ACDELCO TDS link.

[kpeters59]

Thanks for replying!

I seem to have wiring diagrams, but it's unclear which plug on the PCM and Fuse Block is which.









I was having trouble getting photos inserted.

So which harness at the PCM would have the fan wires?

And which one at the fuse block?

Thanks!

-KP

[kpeters59]

Ok, I found this on LT1swap:

Engine Control Module X1 (L99 or LS3) BLACK CONNECTOR, 73 PIN, 2010 CAMARO

Engine Control Module X2 (L99 or LS3) GRAY CONNECTOR, BLACK COVER, 80 PIN

https://lt1swap.com/2010camaro_ecm_pinouts.htm



Dang, it's like secret information...

-KP

[gtstorey]

Originally Posted by kpeters59

Dang, it's like secret information...

-KP

Not secret, just not easy for free. $22 would get you access to all the service manual information for 3 days. Download all the wiring diagrams, pinouts and connector information.

[kpeters59]

I have that information.

What wasn't easy to locate was the identification of which plug was which.
Even LT1swap's information was hardly discoverable with just a single line of information.

I'll figure out which pin on which plug is for the fan relays and go from there.

My expectation is that it's most likely in the PCM to Relay connection.

I wouldn't expect the PCM is only sometimes getting the relay coil pulled to ground. Unless it's a grounding issue at the PCM?

How can I get to the underside of the fuse block, if the issue is there? I also haven't located much information on that.

Thanks,

-KP


Edit:

I also found this:

PCM located on passenger side in engine bay.

"X1" (black) is toward the front of the vehicle on the PCM.
"X2" (gray) is toward the rear of the vehicle on the PCM.
You can only see the colors (blk and gray) once the connectors are disconnected.

Here:

https://www.camaro5.com/forums/showthread.php?t=48639

[gtstorey]

The oem service manual will show exactly which connector is which in relation to the call outs on the oem wiring diagrams. If you are looking at that as a source, you aren't finding the correct pages.

[kpeters59]

Thanks!

So X1 is not the black PCM connector like in the image I posted above?
And X2 is not the gray connector at the PCM?

-KP

[gtstorey]

I think what acutron42 posted is a fusebox connector, not the ecm. It actually says fuse block on the second image.

[kpeters59]

I get that.

It's just that the documentation I have calls X1 the Black PCM connector and X2 the Grey PCM connector.

I thought X3 was the Fuse Box connector.

.-KP

[acutron42]

Good observation GT, I will see if I can find the Bosch connector info.

[acutron42]

My bad, I uploaded the wrong pics. I deleted that post & here is the Bosch K20 X1 info.