And what do they do?

I know there are quite a few.

And maybe a few less if you dont have NAV or On Star.

 

WOW! I dunno, but like you say: "quite a few".

PCM (Power Control Module, or Power train Control Module) - the engine, may also be referred to as ECM, but I think PCM is the politically correct C6 term.

BCM (Body Control Module) - the body (?).

EBCM (Electronic Brake Control Module) - the ABS.

There's something that does TM, but nobody knows how it works, so no telling what unit (or combination of units) it comes from.

The auto trans has a computer controller, a lot of input may come from the PCM because a tuner can tweak many functions (shift revs, mph, firmness).

The manual has the CAGS (probably comes from the PCM because tuners can turn it off).

Active Handling and Traction Control - I don't know what controls them, probably the BCM and EBCM. There are also yaw sensors, accelerometers, and maybe some other stuff that provides inputs. If you have F55 they interact with that.

RCDLR (Remote Control Door Lock Receiver) - I guess there is a computer in this unit. You can program auto door locking, etc. This unit also is involved in the Tire Pressure Monitor System along with the BCM.

DIC - I don't know whether there is a separate computer that runs it, or whether most of the stuff comes from other sources. I suspect it has its own computer.

If you have the F55 Magnetic Selective Ride Control there is a computer that gets a bunch of sensor inputs and decides what to do as far as stiffening/softening individual shocks.

Well, those are just a few that I can think of to start with. I hope more knowledgeable folks will chip in better info, or correct me if I'm giving bad info.

Bob

 

I think the DIC is run by the BCM. But the HUD has some processing in it. There's also a communications processor - forget the name - under the carpet in the left rear compartment. That does the OnStar and (in some markets) other stuff. And of course the radio / nav has a processor.

I think the C6 uses separate ECM and TCM (Transmission Control Module) rather than a single PCM.

There's a diagram in the service manual showing the CAN and class 2 busses; I'll take a look at that and see what all are on them. That should be all the processors in the car.

 

Okay, here's the list of what's on the communication busses:

GMLAN (CAN)
pins 6 and 14 on the DLC (Data Link Connector)
BCM (Body Control Module)
VCIM (Vehicle Communications Interface Module) (w/UE1 OnStar)
SCM Suspension Control Module, AKA ESC (Electronic Suspension Control)
TCM Transmission Control Module
EBCM Electronic Brake Control Module (ABS)
ECM Engine Control Module

SAE J1850 (Class 2)
pins 4 and 5 on the DLC (Data Link Connector)
HUD (Head Up Display)
IPC (Instrument Panel Cluster)
DDSA (Driver Door Switch Assembly)
DDM (Driver Door Module)
SDM (Inflatable Restraint Sensing and Diagnostic Module)
SCM (Memory Seat Control Module)
Steering Column Lock Control Module
Digital Radio Receiver (U2K XM radio)
HVAC Control Module
Radio
RCDLR (Remote Control Door Lock Receiver)
BCM (Body Control Module)
FPDM (Front Passenger Door Module)
Folding Top Module (w/CM7 power convertible top)
VCIM Vehicle Communications Interface Module (w/UE1 OnStar)

Some of these seem to have more than one name, and a few don't have an acronym. Of course the BCM is on both busses, and it acts as a gateway between them. But it's a pretty good bet that each of the items listed (except of course for the pin assignments on the DLC) has a processor inside. It pretty much needs to in order to talk to the bus.

Any more its simply cheaper to put in a CPU than to run a couple extra wires, which makes sense in a way - silicon is cheaper than copper. And lighter!

It is interesting to note that the SCLM (Steering Column Lock Module) is on the Class 2 bus. I know this has been a source of trouble, and may be related to DBS, and that many think that DBS may be related to things on the bus waking up. It would be interesting (and probably possible) to monitor all the communications on the bus to trap any spurious wakeup messages.

 

Wow. Thanks for all that info!

Sure would be fun to log all that information during different driving conditions and see what was going.

We are in the hands of software more then ever these days.

 

Great info!

That extended warranty I got might be used more for some of this stuff than the mechanical parts of the car. I think after 5 or 6 years it will just be time to get a new 'Vette instead of dealing with all this stuff when it starts going bad.

Bob

 

Well it would be interesting to log it, now wouldn't it. Scan tools and tuning software will log at least some of it, but I'm not sure how much. And of course there's always the issue of interperating it, as the stuff coming across the bus is in codes. Some of it (RPM, speed, etc.) would be easy enough, but other codes might take some figuring out.

Now you've got me thinking about this. Suppose we logged both CAN and class 2 to some sort of storage device, maybe a flash memory card. The CAN has a max data rate of 500KBPS, so a 1GB card should be able to log over 4 hours worth of data at 100% use, which I'm sure it never gets to. That would cover most trips or track sessions easily enough.

Let's see .. a CAN PHY, CAN controller, MCU, SPI controller, SD card socket, power managment ... of course lots of microprocessors (like Motorola DSPs and some AIMs) have CAN and SPI onboard already ... low-power real-time clock (watch chip) ... have to figure out the SAE VPW interface ... shouldn't be too hard to do.

Just what I need. Another project.

 

might be a money maker project.

Something that logs the important stuff,
and can be played back with a graphical representation of what the car is doing. Where the steering wheel was pointed, what the yaw sensor was doing, how many Gs, when AH kicked in and on which tire, when it backed off the throttle. Cool stuff to know.
Of course GM surely has something whizz bang like that it wont share with us from developing this stuff over the years.

 

Let's see .. a CAN PHY, CAN controller, MCU, SPI controller, SD card socket, power managment ... of course lots of microprocessors (like Motorola DSPs and some AIMs) have CAN and SPI onboard already ... low-power real-time clock (watch chip) ... have to figure out the SAE VPW interface ... shouldn't be too hard to do.

Just what I need. Another project.[/QUOTE]

Pretty Crazy. I came up in the late 60's eary 70's muscle car era where dual point distributors,high capacity condensors,dual line double pumpers and solid lifter cams where the rage.My 67 GTO ran 13.20's and got 8mi/gal. But you change with the times.Now i get in my 06 corvette and have to "think about it " for a few seconds before i push the start button. when the DIC says "welcome Bob" I'm ready to go!!!!! hehe

 

I'm sure GM has something to do this; or maybe they use the Tech II. It would be hard to make money at it; electronic things are such a volume business that one-offs cost a fortune and to get something cheap you have to make a lot of them. And there are the various certifications and so on - at least the FCC class B computing device listing, which can easily run several thousand dollars.

I'd take it from your user name that you know how much a simple gadget like a clock for installation in an airplane costs, due to the FAA approvals required. The FCC isn't quite that bad, but it is still a real pain for small volumes.

However, there are provisions for experimental devices, and one can make and use up to 5 such devices under certain provisions such as "good engineering practice is followed to ensure against interference".

I did an hours' worth of looking into this, and I don't think it would be too hard to build such a gadget. A preliminary bill of materials would include:
Atmel AT89C51CC03 microprocessor
provides "brains", includes CAN and SPI interfaces
also has on-board ADC (to monitor the car's voltage)
Microchip MCP2551 high-speed CAN transceiver
provides the interface to the physical CAN bus
ST M41T94 real-time clock
keeps time, runs on a coin cell when the car's off
SD Card socket - commodity item
PCB (Printed Circuit Board) - to order
20MHz and 32.768KHz crystals
generic components (resistors, capacitors, etc.) from stock

Of course there are many other choices, but these should work with a minimal package count and I can get them in small quantities from Digikey (an electronic parts distributor).

I still need to find a small-volume source for the DLC (OBD-II) connectors and figure out the class 2 VPW protocol. That might take a little breadboarding.

Roughly speaking, this would come to around $500 to $600 for 5 prototypes, half of that being the PCBs. And of course a lot of work that would have to be charged off somewhere if it were a commercial product but doesn't matter if it's just playing around with cars

 

Well, its all what you're used to. A CAN isn't any more complicated than a CAM, and nothing in the world is as complicated as a CARB! At least when it isn't working right. And especially when it isn't working right in one particular situation!

But I would like to know more about what's going on with my car, and the ideal circumstance would be some sort of continous monitor, rather than waiting for a problem to happen and then trying to catch it.

 

This C-6 has over 200 sensors, now if that is not asking for trouble in the future. Electronics are suppose to be superior to mechanical and easier to diagnose and fix yet with these electronics the price of repair goes up and up in price.

 

ONE TOO MANY!

 

That's because the service departments count on people like you to be confused and baffled. Thus they can gouge you more for a repair that's actually simpler and cheaper to do. Same game as the brake shops who charge more to change disc brake pads than to change drum shoes, though the latter are a whole lot more work to do.

 

You are absolutely correct

 

Yep! We are all out to screw the customer

 

My Corvette doesn't have drum brakes The last year of drum brakes for Corvette was 1965

 

Buffy,

If you want to build one of these things to monitor, let me know.

 

It already exists, contact Team ZR-1 they did the BETA testing and I was one of the testers for the Ease scanner that monitors all modules in my 2006 Z06 and also does bi directional.

 

I've done a little more looking (in between installing ceiling fans, no fun at all) and found that STMicroelectronics makes an MCU with both SAE J1850 and CAN support, as well as SPI and some ADCs. It's in a TQFP 100 package and costs under $20 in onesies. This with a VPW interface chip and power controller should make a pretty decent monitor. I've never used an ST9 before, so I'll need to come up with some development tools. If I can find something that'll work for that, the project looks doable.

Of course the other question is are we re-inventing the wheel? It seems like the HPTuners product will do a lot (all?) of this monitoring, and its available for around a grand if you buy a used laptop to run it on.

Translated:
MCU Micro Controller Unit - a computer.
SAE J1850 - GM class 2 - listen to the low-speed data.
CAN - GM GMLAN - listen to the high-speed ECM data.
SPI - Serial Peripheral Interface - used to talk to SD cards.
ADC - Analog Digital Converter - can be used to monitor the battery voltage, etc.
TQFP 100 package - damn small, with itsy-bitsy pins very close together.
VPW - Variable Pulse Width - the electrical protocol used by the class 2 bus.