ok guys...here's what I got. I'm a new cummins owner so please bear with me. I hava a 97 reg cab 4x4 12v truck with 250k. The ac worked fine until the end of last summer when it just quit blowing cold. No big deal.. then the cruise stopped working. The light will come on when you first start the truck up and sometimes it will engage but just once. Once you hit the brakes or turn the cruise off, the light will not come back on and it won't work at all. Doing routine maint. I found a fuse blown for the trailer lights under hood. I replaced it but no difference. I've searched a lot of posts trying to find a solution.. I was thinking PCM might be bad since all my gauges work and my speedo reads under 10 mph(I take that these 2 rule out crankshaft position sensor and vehicle speed sensor) I was thinking PCM since it controls both the ac and the cruise. What do you guys think? I appreciate the help for a newbie in advance. Thanks

 

Hey,
Try the 4x4 and see if that engages similar to the cruise....we have a 1ton (01) that the ac selector and 4x4 and cruise dont work. Its all vacuum related on those trucks (24v's) and i think it is on the 12v's too. Might want to check the lines for vacuum leaks, either check them over or maybe pressurize them w/like 5 psi and see if you can hear air leaking out somewhere and pinpoint it (truck off). see if this helps, good luck

TNutcher

 

thanks for the advice. I tried the 4x4 and it engages fine. any other thoughts out there?