Howdy all,

Went on a bit of a road trip with my truck to visit family recently and discovered the cruise control isn't working. I thought it was just the switches in the steering wheel as I tested the ones on the truck and the on/off button had resistance far greater than what is specified in the manual, but I ordered ones on ebay, tested them, and installed them only to still have issues. Whenever I hit the on/off switch the "CRUISE" light on the dash illuminates for a split second then turns off. I've verified I have no blown fuses in the engine compartment or inside the cab, no vacuum leaks, and I believe the bellows are working as, again, no vacuum leaks and there was no corrosion from the battery on the unit (which I've read in other forum posts can be the issue).

I've had an extremely intermittent P0132/P0135 issue with the vehicle and another user on a separate post suggested it might be my PCM as one of the prior owners certainly replaced it or flashed it at some point as it has "2000 Dodge Ram V8 Gas" written in white sharpie on it, so perhaps I just need a new PCM? If anyone has any other suggestions on how to troubleshoot this before I drop another $350 into my money pit it would be greatly appreciated! Thanks!

 

Guessing you already know how the cruise buttons work. The rest of it, is completely controlled by the PCM. Now, WHY it turns the light right back off again, that one, I just don't know..... Anything in the service manual in the troubleshooting section for cruise?

 

Gonna do a deep dive right now, I'll report back. Unfortunately in my non-infinite wisdom I only took pictures of the cruise switch resistances and didn't include the page number

 

So it appears the only thing I can do is verify that the instrument cluster is functioning (which just confirms if the lights and gauges function, and all of mine are) as it should per pages 565-567 (8J-6 to 8J-8) of the service manual. The "on" is only controlled by the user operated switch while the "off" is controlled by the PCM, either through the brake switch (which is brand new and functional and also wasn't being depressed when it turns off as it turns off even in park) and diagnosing that requires a DRBIII scan tool which I don't have...

 

Check to make sure the brake light switch and the disengage switch, if you have one, is working properly. I tracked a problem down on an '04 Ford Expedition and there were two switches. One for the brake light switch and another, separate one to disengage the system when you hit the brake.

 

Currently I don't have any issues with the brake lights coming on, nor the parking brake, but there is a diagnosis step in the manual (page 576 8J-17) for diagnosing a switch that otherwise doesn't appear to have any issues so I'll check it out tomorrow. It is a switch from Autozone so perhaps it's just chinesium crap, but the post that abuts the brake pedal on my OEM one snapped which is why I had to replace it.

 

On my 96, pushing the button turned the cruise light on, only to show it was 'active', and the other buttons would actually DO something. Don't remember if it works the same way on my 98...... I haven't used the cruise in quite a while.... I just don't drive far enough to make it worth while.

 

Yeah mine will briefly illuminate and then go off; I've tried pushing the other buttons while the light itself is off and I still don't get any cruise control so I'm assuming it's more than just a faulty light in the gauge cluster.

 

For whatever reason, the PCM seems to be turning it back off.... Prolly gonna need a fairly high zoot scanner to determine why...

 

Would you happen to have any recommendations for one? Besides that it appears my other option is just springing for a new PCM, and considering the rather tenuous state of mine (with the random sharpie marker on it indicating it was likely re-flashed at some point) perhaps that is the better option?