The wipers and heater fan work intermittently. They both mostly either work or not work at the same time, but a few times the heater will work while the wipers do not. No other electric components are affected. When they work, about 20% of the time, they are slower than normal (wipers on high are more like the slow setting, fan only turns slowly). I have replaced the wiper motor and pulse board with no change in function. Truck has a new battery. Now I went to start the truck and it just cranks. I get one code, P1626 the theft deterrent thing. I have checked all fuses, relays, ground connections, etc. Any suggestions? Can I have a bad BCM? Or does that not affect wipers and heaters?
Heaters have their own module as well as wipers. The ground in tehwioper motor may be bad or it could be a bad multifunction switch. Make sure all your groundsa re good and check blower relay and resistor by blower.