Working on fixing all my error codes, only one left currently is #4 Temp Sender switch. My Haynes books tells me that it's the one on the front of the I/M, green connector, but by looking online, others are telling me it's the one 1/2 way down the I/M. So I replaced both of them, and for good measure the one right above the thermostat. Light's still on. Would my cold start temp sender be a cause of this? it's the only one I haven't replaced yet. Or, maybe a bad ground to the one on the front of the I/M?

 

Ground is possible. Most likely the cold start injector time switch.

Is your truck hard to start in the morning?

 

Half of the error codes I've had on my truck have been broken wires in the bundle
(half of which were my own fault, laying the harness over the fender during my engine rebuild was a little too much stress for those old wires)
Double check the wiring from the ECU connector to the sensor connectors too..