Not my first rodeo with the P1491 cooling circuit fault. I've probably gone through 8+ fan relays over the 150k miles I've had my WJ for and 3 or 4 fan motors. Current fan relay is brand new - bought 2 off of eBay a while ago- first one lasted probably 2 years, second one, no go. Fan motor is less than a year old (replaced when I replaced radiator last June with a Griffin)
P1491 Rad Fan Control Relay Circuit An open or shorted condition detected in the radiator fan control relay control circuit. This includes PWM solid state relays.
I checked the fan by putting 12v to it and it hums nicely (I know, not the best test since some will work with 12v, but excess load kills relay anyway). Of note, the connector at the fan had a burnt conductor, so I eliminated plug by splicing wires. Also got a new plug for the fan relay - nothing burnt, but it was the original and figured it would be one thing I could rule out. Put the new relay in mentioned above - fan would not turn on with AC or at temp. I rigged the fan to run with the engine and it cooled things just fine. E-Fan only, no mechanical fan.
I'm also now getting P1683 cruise control circuit fault. My cruise hasn't worked for a long time - checked my vacuum hoses numerous times and never found a problem with them, but never had a code pop up and just lived without it.
P1683 SPD CtrL PWR Relay; or S/C 12V Driver Circuit An open or shorted condition detected in the speed control servo power control circuit.
I had been driving around with a small hole in my exhaust head pipe for a few weeks until i could replace the pipe (what a PITA). Likely unrelated, but it's the only work that I did/only change made.
Is there any way that these two codes are related? If I'm throwing parts at this, is there an order in which I should replace parts?
I figured I'll get another fan relay (with a warranty) and try that first. What else can I try (at wits end with this).