Duramax Diesels Forum Truck of the Week
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Old 05-01-2013, 10:53 PM
Gone Nomad Gone Nomad is offline
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Default How to re-wire this connection?

I'm going to change how the device that is currently connected via this 10-pin Delphi connector is controlled:




Without getting into what it is, I already know what I intend to do will work.

But what I'm not sure about is what to do with the wires that will no longer be needed for this device.

My assumption is that I need to connect these two sets together:
CAN LO In to CAN LO OUT
CAN HI In to CAN HI OUT


My assumption is that retains the continuity of CANBUS LO & HI after they are no longer connected to the device they are currently connected to.

Anybody know if that's correct?

Two other wires won't be used either ("J - BCM COMM ENABLE" and "K - Supplier Diagnostic"), but neither of these wires pass through this connector,
so they are evidently used only for diagnostics, with a test cable plugged in between the two sides of the connector shown above.

Thanks!
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Old 05-02-2013, 01:45 AM
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Looks like the auxiliary heater connection. There is a dummy plug for that connection available when the heater is not installed.

You are right. Connect the CAN hi and low so they pass through.
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Old 05-02-2013, 01:35 PM
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"BCM comm enable" is nothing more than a regular +12v hot ignition power feed to provide a discrete "wake up" signal to the module...as opposed to being woken up with a data message alone.
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Old 05-02-2013, 10:43 PM
Gone Nomad Gone Nomad is offline
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Quote:
Originally Posted by Fingers View Post
Looks like the auxiliary heater connection. There is a dummy plug for that connection available when the heater is not installed.
The jumper that is normally plugged into this connector on any van without the K08 fuel-operated heater option is: GM part # 88986245 which gmpartsdirect sells for $100.40 ...and that's about half of retail, and AFAIK cannot be returned, so that's why I didn't order it to

I don't know anyone who has a 2010+ DMax van, but come to think of it, maybe the 2010+ gassers have this connection too, even though it's always unused... and I do know somebody who has a 2012 gas 2500 van.

Quote:
Originally Posted by Fingers View Post
You are right. Connect the CAN hi and low so they pass through.
Thankyou kind sir for confirming this.


BTW...

Maybe you remember me asking you about this a year or two ago when I was still trying to figure out how to make the heater work in standalone mode with the OEM controller. Since that didn't turn out to be cost-effectively feasible, I took the brute force approach: replacing the OEM controller with the "normal" Espar controller (normally ~$375), something that was cost effective only because I snagged a new controller off of ebay for $85:

There were two of those "normal" controllers available, and I tried without success to find another 2010+ Dmax van owner who could use the second one.
I almost bought the second one myself to have just in case, but somebody else finally bought it.

Since the connector on the "normal" Espar controller looks like this:

and since this German-made connector isn't readily available in the US, I'm either going to buy one of these short harnesses from the U.K.:

or (since that thing above is about $60 delivered), most likely I will simply replace the hard-to-find Espar connector with a readily-available male GM Delphi connector pictured in the OP.

And now I won't have to worry about screwing up something when I patch together the now-unused CANBUS wires together. Hopefully the BCM will automatically recognize this as be heater not being installed.

THANKS again!

Last edited by Gone Nomad; 05-02-2013 at 11:06 PM.
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Old 05-02-2013, 10:49 PM
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Quote:
Originally Posted by duratothemax View Post
"BCM comm enable" is nothing more than a regular +12v hot ignition power feed to provide a discrete "wake up" signal to the module...as opposed to being woken up with a data message alone.
OK, to which module?

If referring to the fuel-operated heater connected to this, that "BCM comm enable" line ("J") ends in the connector, so it can't send a signal to the heater without some type of test cable plugged in between the two connectors shown in the OP.

Now you've got me wondering if that was the solution all along (connect that wire), but Greg Landuyt evidently spent quite a while trying to figure out a way to make the OEM heater controller work (because he wanted to create a kit to sell, like his Sprinter kit). The belief is that since the CANBUS literally passes through the controller, the OEM GM controller is customized to work only from coded signals sent from the BCM.

I do appreciate you answering, Ben. You and Fingers are about the only two I would trust on something like this.

Maybe I've stumbled onto where everyone who is not just interested in how big their tires are has gone, now that those seem to be about all that's left on Dieselplace?

Last edited by Gone Nomad; 05-02-2013 at 10:58 PM.
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Old 05-03-2013, 02:47 PM
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Quote:
Originally Posted by Gone Nomad View Post
OK, to which module?
To the fuel operated heater control module. Most modules in the trucks are turned on/off up purely by a "wake up" message over the databus. But more "critical" devices (ECM, TCM, fuel operated heater) also have a discrete "traditional" +12v ignition hot input. So if there is any short in the databus wiring, as long as the module gets +12v on that pin, it will still power up regardless of whether or not it receives a "wake up" message over the databus.

The reason its labeled "BCM comm enable" is kinda a misnomer. The FOH doesnt communicate directly with the BCM per se. But the BCM is the power mode master for the vehicle. It is what receives the discrete signals from the key switch, and then based on which position the key is in, it sends out both a "wake up" data message to the non-critical modules (which rely purely on a data signal to turn on/off like for power windows) and it also outputs a low-current +12v standard ignition hot voltage to the discrete "turn on" signal wires going to the critical modules for redundancy.

SO when it says "BCM comm enable", its referring to the +12v ignition hot power source that comes from the BCM, which, in turn, enables communications (IE, wakes it up/powers it on) on the FOH between it and the ECM...not the BCM.

I mean technically since the FOH and BCM are both on the same high-speed GMLAN databus, they COULD communicate with eachother, but I doubt any BCM <---> FOH comms are going on because the only data the FOH needs to run is stuff it would get from the ECM (coolant temp, engine run flag, ambient air temp)

Apparently the FOH will only run when the engine is running, and ambient air temp is below ~40*. It has different "levels" based on coolant temp. It communicates with the ECM to relay trouble codes to a scan tool. So if it has a fault, it tells the ECM, and the ECM turns on the check engine light. It obviously needs communications with the ECM over GMLAN because it needs coolant temp info, engine run status, and ambient air temp info.

So basically...yeah you could manually power up/wake-up the GM factory FOH on the bench just by feeding it +12v on that "BCM comm enable" wire...but the FOH wouldnt actually fire and start working until it gets engine run data from the ECM over GMLAN.
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Old 05-03-2013, 07:15 PM
Gone Nomad Gone Nomad is offline
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Quote:
Originally Posted by duratothemax View Post
...So basically...yeah you could manually power up/wake-up the GM factory FOH on the bench just by feeding it +12v on that "BCM comm enable" wire... but the FOH wouldnt actually fire and start working until it gets engine run data from the ECM over GMLAN.
OK, thanks....

But there's no way to feed +12v to the heater on the BCM comm enable ("J") because that wire doesn't go into the heater.
That wire stops on the chassis side of the connector, and it's counterpart position ("J") is empty on the heater side of the connector:


That's what I meant about the only way that could be used would be with a diagnostic connector of some kind plugged in between the two sides of the existing connectors.
I guess it's possible that putting 12v onto the "Supplier Diagnostic" ("K") would do that... but I think that line is used to read trouble codes off the heater with one of the Espar Diagnostic tools (page 5). I remember seeing the page from a GM technician's manual on how to diagnose trouble with this heater, and it required using an adapter cable and one of Espar's Diagnostic tools, rather than a Tech II.

But at this point it's an academic issue, because I already have the 'normal' Espar controller that can be used to run the heater in standalone mode.

After I've swapped it out, I could send you the OEM control if you want to tinker with it. If you find a way to enable it, I'd guess that Greg Landuyt would like to buy that solution from you.

Thanks for your input, Ben.

Last edited by Gone Nomad; 05-03-2013 at 07:34 PM.
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