Been checking out my brother’s truck for a couple days. Cooling fans do not kick on high and engine overheats. Took the scan tool home and was able to control fan speed all the way to 90% (high) but will not turn on high when engine overheats (230 degrees). Replaced thermostat and coolant temp sensor (both AC DELCO). After replacement of temp sensor, fans kicked on high right away but then turned down to low speed again. Any recommendations?