ALDL Mode 4 BCM Output Test commands on a VR Commodore

160 And 8192 Baud Aldl
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ALDL Mode 4 BCM Output Test commands on a VR Commodore

Postby picvrss » Tue Sep 10, 2019 11:21 pm

Hello,

This is my first post, on my first forum, and firstly, I have to comment on the wealth of information and experience shared by contributors to pcmhacking - it's amazing stuff.

My profession and interest are in electronics, and this extends to designing and modifying electronic modules for my Commodore VR Series II SS, which I’ve owned for 24 years.

About 20 years ago, I replaced the factory Speed Alert dash module with a real-time ALDL ECM Monitor of my own design. It was based on a Hitachi 6303 microprocessor, and in addition to its primary function as a in-dash scan tool, it also retained the functionality of the original Speed Alert module.

Move on 20 years, and I replaced the ECM Monitor with a new PIC-based design, and added BCM Monitoring and Trip Computer/Fuel Consumption functions, which was easy to achieve.

This then led me to consider adding actuation of various BCM-controlled functions such as the Dome lamp, Indicators and Door Locks using ALDL Mode 4 Output Test commands to the BCM. Such commands have been the subject of several excellent posts on this forum, but these have been for VT - VZ models. Accepting that I might never get access to a Tech 1 from which I could sniff the required ALDL commands, I bought a Vident I-400-Holden scan tool, which was specified as being able to perform Actuator Tests with the VR BCM - in short, it can’t.

However, it does so with a VS BCM. As an example, to turn on the Dome lamp in a VS, the required Mode 4 command is:

$F1, $5D, $04, $00, $10, $00, $00, $40, $00, $00, $5E

I figured the only difference between the command structures for VR and VS should be only in the initial ID byte - $F1 for VS, and $BD for VR – and of course, in the final checksum, so I tried sending the following command to the VR BCM:

$BD, $5D, $04, $00, $10, $00, $00, $40, $00, $00, $92

There was no response from the BCM, nor was there to any Mode 4 command.

Would anyone out there know the command message structure of Mode 4 Output tests on a VR Low-level BCM?

Any advice would be very much appreciated.

PICVRSS

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Re: ALDL Mode 4 BCM Output Test commands on a VR Commodore

Postby picvrss » Mon Nov 11, 2019 12:09 pm

As it turns out, the functional test commands on a VR are done as Mode 3 message frames, not Mode 4, and the frame is one byte shorter than those for a VS.

So, to turn on the dome lamp for example, you send:

$BD, $5C, $03, $00, $10, $00, $40, $00, $00, $94

As is typical of functional test commands, the frame has to be sent periodically, otherwise the function will eventually time out.

Commands for other functions follow the same format.

A really big "Thank you" to Nick and the guys in the Service Department at Alan Mance Holden Footscray for allowing me access to their workshop and Tech 1 scan tool.

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Re: ALDL Mode 4 BCM Output Test commands on a VR Commodore

Postby The1 » Mon Nov 11, 2019 1:23 pm

nice work and thanks for posting, also fun.

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Re: ALDL Mode 4 BCM Output Test commands on a VR Commodore

Postby picvrss » Mon Nov 11, 2019 2:45 pm

Thanks, The1, yes, it is fun, and I'm over the moon after unsuccessfully scouring the Web for ages trying to find this info.

Some additional commands, in case anyone's interested:

Dome lamp ON: $BD, $5C, $03, $00, $10, $00, $40, $00, $00, $94
Dome lamp OFF: $BD, $5C, $03, $00, $10, $00, $00, $00, $00, $D4

Lamps delay drive ON: $BD, $5C, $03, $00, $20, $00, $80, $00, $00, $44
Lamps delay drive OFF: $BD, $5C, $03, $00, $20, $00, $00, $00, $00, $C4

Indicators ON: $BD, $5C, $03, $00, $80, $00, $00, $02, $00, $62
Indicators OFF: $BD, $5C, $03, $00, $80, $00, $00, $00, $00, $64

Central locking LOCK: $BD, $5C, $03, $01, $00, $02, $00, $00, $00, $E1
Central locking UNLOCK: $BD, $5C, $03, $01, $00, $01, $00, $00, $00, $E2

Pwr windows relay ON: $BD, $5C, $03, $04, $00, $10, $00, $00, $00, $D0
Pwr windows relay OFF: $BD, $5C, $03, $04, $00, $00, $00, $00, $00, $E0

Security LED ON: $BD, $5C, $03, $00, $40, $00, $00, $01, $00, $A3
Security LED OFF: $BD, $5C, $03, $00, $40, $00, $00, $00, $00, $A4

There are commands for other functions that I'll post when I test them out. The Tech 1 tool allows only those relevant to the particular level of BCM.

Mine was originally a LOW-series BCM, which I mofified by adding the missing PCB components that interface to Cruise control (I did it in a manual tranny SS!) and power windows.

So, it still identifies itself to the Tech 1 as a LOW - hence the limited command set - but it has the hardware functionality of a MID-series BCM.

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Re: ALDL Mode 4 BCM Output Test commands on a VR Commodore

Postby Biggvl » Mon Nov 11, 2019 2:52 pm

cool :thumbup: thanks for posting
According to chemistry, alcohol is a solution...

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