What is the strange yellowish track-facing glow emitted from underneath the coach engines of a Class 185?!

From 29 August 2026, When I board 185107 (rear half of the service) by the front end coach door pair (on coach 4 in the 2x-185 formation) from the 07:26 service from Cleethorpes to Liverpool Lime Street with formation of 185102(front) and 185107(rear), I saw a strange yellowish glow (track facing) emitted underneath the ENTIRE coach shining onto the tracks.

I saw it through the gap between the train and the platform whilst boarding 185107 on 'coach 4' by the nearest passenger door pair to the front cab(facing 185102).
Just seen it for real.

What does the underneath track-facing glow of light even mean under the ENTIRE class 185 coach structure?

CorbeauDesiro said:

.....I saw it through the gap between the train and the platform whilst boarding 185107 on 'coach 4' by the nearest passenger door pair to the front cab(facing 185102)....

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As you saw it through the gap between train and platform, perhaps it was to draw your attention to the said gap while boarding the train? There are noticeable differences over the network in platform height and edge-train distance and this may be a way of warning people to be careful when the gap is larger than usual?

Purely speculation here, but is it possible that there's some form of track monitoring equipment mounted under that coach (cameras, lasers, LIDAR)? Though I don't know whether any of those emit yellow visible light.

DelW said:

Purely speculation here, but is it possible that there's some form of track monitoring equipment mounted under that coach (cameras, lasers, LIDAR)? Though I don't know whether any of those emit yellow visible light.

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I did think that too, SWT / SWR had a 158 doing similar for a while as well.

fgwrich said:

I did think that too, SWT / SWR had a 158 doing similar for a while as well.

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... which got several reports of train smoking/on fire.