Red light when headlights on

[Stevieboy217]

Hello, I have an 1987 diesel T25 with an aaz lump in it.
I have recently started to have an issue where the red flashing coolant light comes on if it turn my headlights on. And sometimes when I turn my full beams on, indicators, horn, washers, wipers etc.
New temp sensor, level sensor, SHC Dash PCB, all earth's cleaned in the engine bay and the crowns behind the fuse box and new earths run under the dash.

Happened a little after the PCB was put in but not immediately after.
So yeah, not sure really and after some help as I'm using it for work so dark mornings and evenings and would rather not have this issue!

Many thanks

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[Aidan]

unplug your coolant level sensor 'relay', usually a #43, in position 3, 3rd from left top row, on the relay plate/fuseboard, and plug it back in again, maybe a couple of times to clean the contacts; sounds like you are getting a voltage drop that is enough to cause the sensor unit to report low coolant level; it could be earths issue, damp caused corrosion especially, or voltage regulator in the dash or SHC unit is causing the issue, but my suggestion is no cost and may work

[Stevieboy217]

unplug your coolant level sensor 'relay', usually a #43, in position 3, 3rd from left top row, on the relay plate/fuseboard, and plug it back in again, maybe a couple of times to clean the contacts; sounds like you are getting a voltage drop that is enough to cause the sensor unit to report low coolant level; it could be earths issue, damp caused corrosion especially, or voltage regulator in the dash or SHC unit is causing the issue, but my suggestion is no cost and may work

Okie dokie, I'll have a look at that this weekend cheers

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[AngeloEvs]

Check the condition of the numerous earth connections at the Earth crown located on the pillar next to the fuse box. There are a number of earth connections that generate heat when Headlights, Radiator Fan, etc are on - the spade connectors on the Crown suffer heat damage creating all sorts of earth connection issues.