Motorhome Mag/Limp Mode

[RustyJC]

Quote:

Originally Posted by ron55 Why and how should the cruise set the vehicle into limp mode?

If the Workhorse cruise control system works like most other cruise control systems today, the cruise control function is integrated into the engine control module (ECM) where the ECM software handles the cruise control logic.

The "resume" function was never intended to operate like the "accelerate" or "decelerate/coast" functions. Whereas one can hold down, let's say, the "accelerate" button as long as it takes until the desired speed is reached, the "resume" function is programmed to look for a MOMENTARY activation signal that tells the ECU to return the vehicle to its last speed setting with the acceleration or deceleration required being controlled by the ECU. In all likelihood, the software programmers never anticipated that someone would hold down the button when going into the "resume" mode for more than 1 second. This unanticipated event (i.e., receiving multiple/continuous "resume" signal(s) instead of one momentary signal) could easily throw the ECU software for a loop which would put the ECU into a default or "limp" mode until it was rebooted by turning off the ignition and restarting the unit.

I'm not saying that's what IS happening, but rather that's what COULD BE happening.

Any time I'm using "resume", I'll bring the vehicle as close as possible to the speed setting with the accelerator and then tap the "resume" button to engage the cruise control - this avoids having the ECU accelerate the vehicle at or near full throttle if, say, I engage "resume" from a vehicle speed 10 or 20 MPH below the cruise control's setpoint.

Rusty

[ron55]

I have a aero force gauge in my ob2 it catches codes but the cruise don't throw a code. for a while in 2005 and 2006 I would get a low voltage to the manifold pressure sensor ( I forget the code #) but I guess it quit that.
There was another guy or two on here that said they had the same crusie deal.
I only brought it up, I thought it might help the originator of this post. Its no problem I can work around it.

[DriVer]

Quote:

Originally Posted by ron55 I have a aero force gauge in my ob2 it catches codes but the cruise don't throw a code. for a while in 2005 and 2006 I would get a low voltage to the manifold pressure sensor ( I forget the code #) but I guess it quit that. There was another guy or two on here that said they had the same crusie deal.

You might need a T2 to scan for that type of DTC.

[richard12]

Lots of good responses, thanks. To those of you who can cause it to fail at will, have you tried to get a fix from any service center???? Still haven't tried to cause a failure with the CC, been on 2 lane highways with no safe place to pull into if it fails. Again, however, I restate that it has never failed when using the CC. In fact it has failed in the past several times when just starting the engine. But will still try to cause it to fail using the CC when I can. Will keep you all posted.

Richard

[Full-Timers]

Quote:

Originally Posted by RustyJC If the Workhorse cruise control system works like most other cruise control systems today, the cruise control function is integrated into the engine control module (ECM) where the ECM software handles the cruise control logic. The "resume" function was never intended to operate like the "accelerate" or "decelerate/coast" functions. Whereas one can hold down, let's say, the "accelerate" button as long as it takes until the desired speed is reached,Rusty

Well my Workhorse owner’s manual states as follows:
If you hold the switch at R/A longer than half a second the vehicle will keep going faster until you release the switch…
It also says:
There are two ways to go to a higher speed;
Move the switch from ON to R/A. Hold it there until you get up to the speed you want, and then release the switch.

[DriVer]

Quote:

Originally Posted by Full-Timers Well my Workhorse owner’s manual states as follows:.

Full-Timers, The last time I checked mone works just the way it's described in your post. I have not been able to generate a DTC while holding the "Resume".

["007"]

Let it slip off your finger and see what happens.

[RustyJC]

Quote:

Originally Posted by Full-Timers Well my Workhorse owner’s manual states as follows:

OK, on mine, the "resume" function works when the cruise control is on but has been disengaged by brake application, etc., while the "accelerate" function works when the cruise control is already on and engaged. The functions share the same button but are separate algorithms. My understanding was that the MH went into limp mode when the resume function was engaged for more than one second. If that's in error, I apologize for saying anything and will butt out of this discussion.

Rusty