Does anyone know how and what to test for code 1491 fan relay problem

 

What are you driving?

 

2000 Dakota 4.7 4x4 club cab

 

Also, to test actual relay, you can try swapping relays with an identical relay from nearby. Just be aware that if bad, it will affect the circuit from where you took it, in turn.

 

I put a new relay and fuses in, and still no fan, I put 12 v to the spot 87 and the fan came on, someone told me if I unplug the temp sending unit and if the fan came on the ecu is good, if no fan, the ecu is bad? so for now I ordered a new PCM/ECU?

In one of the plugs on the ecu the one to the back, or say to the right had oily like stuff in it? not suppose to be there wasn't dialectic grease? like tobacco juice ? lol