7/29/2019 april08_p26_27.pdf

http://slidepdf.com/reader/full/april08p2627pdf 1/2

By Jeff Smit

“Y

ou’ll never have to work onthat,” I remember my bosstelling me back in the 1970s,when, as an apprentice, I

found myself staring unbelieving at thewonders of the VB Commodore and XDFalcon electronic ignition systems.

I quickly learned that if we don’t accept thefact that we will all have to ‘work on that’ –whatever ‘that’ is – we will never keep upin our industry.

Not only do we have to repair these things,but the reality is that even that will bedifcult unless we understand how they

work.

Let’s look more closely at the technology inthe new VE Holden Commodore series.Along with the now old hat systems likesatellite navigation and trip computer,controlled by a scroll wheel and buttons onthe steering wheel, the VE comes with twopriority keys which store individual driverinformation.

Some of the stored detail includespersonalised settings for trip computer,seat and mirror settings, radio stations andeven the driver’s favourite instrumentation

settings and illumination.

At night, the interior lighting can be setto illuminate only the speedometer.To continue to deter the theft of radiosystems, the radio, instrument cluster andother key components are electronicallylinked to the vehicle and will not operate inany other vehicle.

The audio system is Blue Tooth compatibleand also will accept MP3 players via aninput jack on the face of the radio. A rearDVD player folds down to keep the kids

happy on those long trips.

The greatest advancement is in the HoldenAssist telematics. This new system allowsthe vehicle to receive and send data.

For example, if any of the air bags havebeen deployed, the system noties an

operator who will attempt to speak to thedriver via the radio system. If the operatordoes not receive a response, emergencyservices are notied and told the vehicle’s

exact position by the on-board satellitenavigation system.

If you lock yourself out of the vehicle, anoperator can conrm that you’re the owner,

then unlock the vehicle remotely. For roadside assistance, a press of a button andthey will know exactly where you are.

The VE Commodore has up to 30computers or modules that controlfunctions like engine operation,transmission, power steering, anti lockbrakes, telematics, instrument cluster,climate control and theft deterrent.

Here are just some of the control modules.

Those in red are part of the high speedsystem and the rest are on the low speedsystem.

Engine control module (ECM)

Transmission control module (TCM)

Steering wheel angle sensor (SAS)

Electronic brake control module (EBCM) 

including  Electronic stability program (ESP)

Traction control system (TCS)

 Antilock braking system (ABS)

Telematics (TELE)

Instrument panel cluster (IPC)

Heating, ventilation, air conditioning (HVAC)

Body control module (BCM).Theft deterrent module (TDM)

Integrated radio chassis (IRC)

Remote function actuator (RFA)

Rear seat entertainment (RSE)

 Automatic headlamp levelling (AHL)

Navigation interface module (NIM)

Remote function actuator (RFA)

So how do you get allthese electronic modules

to talk to each other? 

Since about 2003, a growing numberof vehicles have been built with a newonboard communications protocol calledCAN (Controller Area Network).

CAN is essentially an engineeringstandard for how computers and modulestalk to one another via the serial data busin a vehicle’s wiring system.

The CAN protocol was created by Bosch inanticipation of future advances in onboardelectronics. The rst production application

was on several Mercedes-Benz models.

If you’re not up to speed on the latestelectronics and don’t know a data bus froma commuter bus, diagnosing CAN systemswill be a challenge.

Even so, you don’t have to be an engineerto perform basic diagnostics on CAN

equipped vehicles because the diagnosticsare essentially the same as OBD IIvehicles.

The only difference is that you need aCAN-compliant scan tool to read thevehicle serial data.

Like many current vehicles, information ina CAN-equipped vehicle is shared over aserial data bus.

The bus is the circuit that carries all theelectronic chatter between modules.

The new VE commodore requires a high-speed data bus to handle the volume ofinformation going back and forth betweensome of the more important safety relatedmodules.

In 1995, GM introduced its own data bus tohandle communication between modules.

The system ran at a speed of approx10,000 bits per second (10 Kbps), whichwas more than adequate for vehicles adecade ago.

For the VE, GM moved to their nextgeneration data bus system whichthey called “GM LAN” (GM Local AreaNetwork). Holden has added the capabilityto operate at two speeds on two separatebuses; a low speed 33 Kbps bus and ahigh speed 500 Kbps bus.

The low speed side of the GM LAN system

operates on a single wire bus to handlebody-related control functions, while thehigh speed bus uses two wires to carrydata between the powertrain, transmissionand antilock brake modules.

A ‘gateway’ node connects the highspeed bus and low speed bus and allowsinformation to be shared back and forth.

For example, the radio (which is connectedto the low speed bus) may adjust volumebased on engine speed and vehicle speed(from the high speed bus) to offset road

noise.

(More on controller area networks and diagnostics on these systems in future editions 

of TaT).

The diagram on the next page shows thebasic conguration of the high and low

speed GM LAN. 

CAN do technology:

You’d better not miss the ‘bus’

© GM Corp

Holden’s VE Lumina

The Automotive Technician 26

7/29/2019 april08_p26_27.pdf

http://slidepdf.com/reader/full/april08p2627pdf 2/2

The Automotive Technician 15

8 16

1 9

BCM TCM SAS EBCM AHL ECM

120120

Linkto low

speed

High speed

GM LAN

X40 diagnostic plug

HVAC   SDM NIMTELE IRC RSE IPC SIC TDM

 MCM   SIM   RFA

Low speed GM LAN

Latest technology in GM’s VE

BCM body control moduleTCM transmission control moduleSAS steering angle sensor

EBCM electronic brake control moduleAHL automatic headlight levellingECM engine control module

Glossary of abbreviations

HVAC heating, ventilation, a/cTDM theft deterrent moduleSIC secondary information centreIPC instrument panel clusterRSE rear seat entertainmentIRC integrated radio chassis

TELE telematicsNIM navigation interface moduleSDM sensing diagnostic moduleMCM mirror control moduleSIM seat interface moduleRFA remote function actuator

© GM Corp

The Automotive Technician 27