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Re: VT Data Bus Logging
Posted: Fri Sep 10, 2010 2:55 pm
by charlay86
It would be interesting to log on both the primary and aux. uarts to see what conditions are required for the BCM to connect/disconnect them.
Re: VT Data Bus Logging
Posted: Fri Sep 10, 2010 2:57 pm
by Jayme
its all in the workshop manual. it disconnects them for 5 seconds if the VATS fails to try to reduce clutter on the bus and give vats a chance to get through, then reconects them again.
Re: VT Data Bus Logging
Posted: Tue Oct 05, 2010 7:33 am
by Dec_head
I have a vt v6 if i can help with any of this let me know
Re: VT Data Bus Logging
Posted: Sat May 07, 2022 9:34 pm
by Madchuska
Can anyone share what needs to be injected into the bus to trigger the low speed cooling fan via the bcm?
Re: VT Data Bus Logging
Posted: Sun May 08, 2022 8:11 pm
by pman92
Madchuska wrote:Can anyone share what needs to be injected into the bus to trigger the low speed cooling fan via the bcm?
On VR/VS there is a specific request data frame sent from pcm to bcm, followed by an acknowledgement from bcm to pcm.
On VT onwards the request is part of the data that is broadcast by the PCM (with heaps of other stuff mainly for the dash cluster). The BCM then includes an acknowledgement as part of its broadcast data.
Re: VT Data Bus Logging
Posted: Mon May 09, 2022 2:20 pm
by Madchuska
pman92 wrote:Madchuska wrote:Can anyone share what needs to be injected into the bus to trigger the low speed cooling fan via the bcm?
On VR/VS there is a specific request data frame sent from pcm to bcm, followed by an acknowledgement from bcm to pcm.
On VT onwards the request is part of the data that is broadcast by the PCM (with heaps of other stuff mainly for the dash cluster). The BCM then includes an acknowledgement as part of its broadcast data.
Thanks, any idea specifically which bit in VT/VX triggers the low speed fan?
Re: VT Data Bus Logging
Posted: Mon May 09, 2022 7:08 pm
by pman92
It's a single bit in the 11th byte of data (after message ID and data length bytes).
Someone already put together a nice PDF, see here
viewtopic.php?f=10&t=6811&p=101184#p101184
There's actually 2 bits, "Low Speed Fan" is just to request it on and off normally. "Low Speed Fan Run On" requests the BCM to keep the fan on for a while after the ignition is turned off I believe.