You may well be right, but the relay's problem is usually dry solder joints and the fault could be triggered by the rise in temperature under the hood after the car is stopped.
Relay looks the same and is under the plastic cover behind the battery. Jump terminals 30 and 87 to test run the pump(s)
'08 Chrysler 300CRD (MB OM 642 engine)
'95 E220 estate
'89 230TE (R.I.P.)