Need info on P2600 code

[Dale_K]

I've noticed my 2018 3.6 has been slow to warm up. My first thought was a weak thermostat and I put off fixing it for a while since it would eventually reach temperature and the trans and oil temp readings were OK.

But eventually the check engine light came on and I expected to find a P0128 code for the thermostat but instead I got a P2600 code. I need some help with someone with access to RAM service data to understand what conditions cause this code to set. I replaced the thermostat with and genuine Mopar unit but I'm not sure it's really fixed. The truck still seems somewhat slow to warm up but it eventually does reach temperature.

Some folks seem to think it's the 3-way coolant valve but the oil and trans temps look OK. The heater works well. The electric fan seems to be functioning normally. I have noticed the grill shutters are open with the truck stationary at idle and the HVAC turned off. There is no code set for the grill shutters but I would think the shutters would be closed under these conditions.

So I don't know how to diagnose this without understanding what sets the code. I also need to know how to test the grill shutters.

 

[MADDOG]

The P2600 trouble code is usually the result of a faulty coolant pump control relay.

However, the code can also be caused by damaged electrical components (such as wires, connectors, fuses, and harnesses) in the controller area network (CAN) bus, a broken ground wire, or a loose control module ground strap.

 

[Dale_K]

Thanks for the reply. Since the 3.6 has a mechanical water pump I doubt it has a control relay related to the pump but I don't actually have service data (wish I did).