Over temp cutoff?

I'm paranoid. My 1999 ML320 just had a new fuel pump installed. The upgrade wiring for the front fans is not installed. After a 250 mile trip (outside Temp 100+) the truck failed to start after sitting for a short time (15-20 Min). Drove another vehicle while it cooled. It started fine after about 1 hr. of sitting . I had checked to temp gage all during the trip and it never got much higher than usual. Does the ML 320 have some type of cutoff switch that inhibits starting if the coolant it hotter than normal? It acted like it did before the new fuel pump was installed or like it had a vapor lock. I have been putting off getting the new wiring harness until summer, but we had a record hot day that day. Guess I need to get the new harness.

Dick C.