VT Data Bus Logging

160 And 8192 Baud Aldl
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charlay86
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Re: VT Data Bus Logging

Post 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.
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Jayme
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Re: VT Data Bus Logging

Post 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.
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Dec_head
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Re: VT Data Bus Logging

Post by Dec_head »

I have a vt v6 if i can help with any of this let me know
Madchuska
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Re: VT Data Bus Logging

Post by Madchuska »

Can anyone share what needs to be injected into the bus to trigger the low speed cooling fan via the bcm?
pman92
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Re: VT Data Bus Logging

Post 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.
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Madchuska
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Re: VT Data Bus Logging

Post 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?
pman92
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Re: VT Data Bus Logging

Post 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.
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