In Deploying Functional Grammar (Martin et al. 2010: 124), the following clauses are said to be 'best treated as behavioural':
the tyres went 'screech!'the little engine went 'wheeee!'the car went 'bang!'
This is a very strange analysis, not least because behavioural processes are processes of psychological and physiological behaviour.
Looked at from above, in terms of the meaning being realised, these are creative happenings (making noises).
Looked at from their own level, in terms of the wording that realises the meaning, these are verbal clauses quoting locutions (cf and she went "Oh my God!").
They are therefore metaphorical clauses in which a material happening [meaning] is realised as a verbal projection nexus [wording] — one stylistic resource for personifying inanimate objects in children's stories.
The source of this confusion — aside from not taking a trinocular perspective — appears to be the unsupported claim that behavioural processes include 'processes which concern the creation of a symbolic representation' (ibid) — though it is more likely that this was added as an ad hoc afterthought intended to justify the analysis.
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Halliday & Matthiessen (2004: 252):
… while ‘behavioural’ clauses do not ‘project’ indirect speech or thought, they often appear in fictional narrative introducing direct speech, as a means of attaching a behavioural feature to the verbal process of ‘saying’.For example: "She's responsible", they gossiped.
