Low fan relay not working correctly? If you have a burned wire at the starter, one of the relays will not work
Pull the connectors off the relays on the drivers side off, get your meter and check both big fat red wires for 12v positive power, they should always be hot. Check the connections, make sure there isnt too much tar from the original relays seeping from years of abuse.
Reconnect wiring if you have 12v+
Then start the car and get it to 180 or so, TWEAK CHIP IS SET FOR 160° LOW FAN TURN ON normally.
If the fan does not come on and the temp is 180° or so, smack the relays and see if the fan comes on.
Id say your low fan relay isnt getting a signal, or no power, or its bad.
Since the high speed fan relay works, the fan is good, hopefully the connection is too.
BW