Club 80-90 Forums

My low coolant warning light has never worked. Reading an ozzie forum it says that I need a 42 relay on a late cooling system as the 43 doesn't work on low coolant, Is that right?

First, does the temp gauge LED flash for a few seconds when the ignition is switched on? If not, the problem is the temp gauge and there are several causes for the LED to stop functioning.



Regards the module 42 and 43, both will work. They are electronic modules rather than relays.

Yes it flashes for a few seconds just doesn't work when coolant gets low. Should it be a 42 relay?

if it self tests then its the sender in the header tank, or its wiring .
relay 43 is just a updated version of relay 42, which sent mixed messages when coolant low , making the gauge go up falsely, so they revised it .

easy to test, unplug the sender in the header tank and use a paperclip to join the two contacts on the plug you just pulled off, if it flashes then the wiring is ok, and the sender is at fault, if it does not, the wiring is the issue , normally in the black junction box or the bit from there to the actual header tank

......just to add, when you remove the connection, there is a delay of a minute or so before the module triggers the LED so disconnect and wait for the LED to flash. If it doesn't, then before replacing the module check it is actually in the correct position in the fuse/ relay box. It is possible to test the module but do the test first.......

Thanks for the advice. Still in a fixed brace so I'll recruit a willing family member to do the test.

Thanks for the advice. Still in a fixed brace so I'll recruit a willing family member to do the test.