Cruise issue (1 Viewer)

[COS80]

Hello. Today, as I was driving my 97 LX 450 up a long grade with the cruise control on, I felt what I thought was the engine stumbling, but then I noticed the cruise light in the cluster blinking on and off. Turning the cruise off and back on seemed to clear the issue; however, on the return drive down that same grade, the cruise kept turning itself completely off (not just pausing, as though I had braked - dash light off, off). It doesn't seem to turn itself off if it's not active (in other words if it's on but not currently controlling the throttle). I've never seen anything like this before, so I don't know where to even start. Anyone have suggestions on what I should look into?

Also, I'm not sure if it's relevant, but I have also noticed the speedo needle swinging erratically, but never at the same time as the cruise turning itself off. Today I caught it swinging back to zero from 40 or so, as I was almost stopped at a stop sign. I've seen this a few times before today.

 

[Rusty Marlin]

The erratic speedo signal is killing the cruise, its happening so fast you're just not seeing it. I had this once when moisture infiltrated the seals.
What fixed mine was pulling the plug at the transfer case and cleaning all the contacts and then sealing the plug with silicon grease on the rubber seal.
It may be that simple for you, or it could be a corroded wire or a bad speedo sending unit.
There is a way to read the CC error codes via a jumper in the Diagnostic Box against the firewall and a key turn sequence; it's in the FSM.

 

[COS80]

Thanks, Rusty, that's a lot to start with. Does that box on the firewall provide different codes than the OBD II port?

 

[Rusty Marlin]

Yes, it will flash codes on the Odometer like the old OBD I stuff. You can also get ABS codes from it. It's been a couple years but IIRC it will give you the ABS codes (if there are any) then the CC codes (if there are any). It's all in the FSM and wicked easy to do, just need a bent paper clip for a jumper.

 

[COS80]

I started looking into this (finally) today. I didn't see anything wrong with the harness on the sensor in the transfer case, but I didn't dig too deep on that. The sensor wiggles a little - might that be the issue?

I'll spend some more time on this tomorrow, inc. the other sensor in the transmission.