Hopefully I'm posting in the right spot.

My SES light is on, and I'm getting code 1642. I have been doing searches on the code and have done some test and not sure of the next step. So far I have tested the relays and wiring and all is good. I have 12v showing at the c100 on the dark blue wire and when I ground out the H & J at c100 the low and high speeds of the fan kick on. So it seems everything from the c100 to the fans is all in check. What else could be causing the SES light. At highway speeds the car runs nice and cool. Tends to run hotter with AC on. With out AC on the temps climb up to 240 or so then come back down to 210ish then back up.

I plan on doing a 160 thermostat in the near future to try to keep temps down more, but I have to get my car inspected and it sounds like Jersey is pretty strict with the SES being on even though its not a emissions code.

 

Well, you're on the right track. According to my OBDII book, it's a problem with fan relays 2 and 3 circuit.

 

So my friend and I checked the wire for Fans 2 & 3 from c100 to the pcm and there was a break in the wire. Soldered it back together and all is well.

The wire sheathing was still intact so it looked fine at first but had no continuity so we knew it was bad. The break was not even an inch from the c100 connector.

Very glad it wasn't the PCM.