I have everything installed on my 2009 base model, but with the Cruise Control on, and when I press "Set", my car goes into limp mode. I've checked my connections and the only thing I can think of has to do with the fact that there is a discrepancy in the manual. The pictured VSS wire has an arrow pointing to a totally different one than is in the diagram.


I have the VSS wire installed on pin 38 which is gray, but the pic is pointing to a different pin.





And am I supposed to tap into the VSS, or just cut it and route it to the module?

 

um... maybe the picture isn't pointing at the pin slot, but the grey wire.

oddy enough, this diagram doesn't list it as VSS, but ABS/VSA (maybe it's the VSS wire used for VSA)

https://www.fitfreak.net/forums/2nd-...tml#post593795

 

Yeah, I noticed that, too. But I must have it plugged in correctly, because I have pressed the Set/Accel/Res buttons when going under 20mph and nothing happens, it is only when I am up to speed that it will throw a CEL and go into Limp Mode, meaning that the module knows how fast I am going.

This is an Automatic, and so the clutch +/- wires go nowhere, right? I hooked them together to see if that would fix it, but same thing happens.

I've checked and re-checked my soldering and connections, and they all look good.

 

Reading their, incredibly unhelpful installation manual... http://www.rostra.com/manuals/250-1855_Form5221G.pdf

They list two things that might cause limp mode. One dealing with the red ignition wire and the other dealing with black ground wire.

This is some goofy ass shit. Thank goodness I don't have to deal with it.

 

Crap, I have troubleshot both of those things and they are connected properly. I'll be ringing up Rostra Tech Support in the morning... I may have received a faulty unit, and I also read from a Doge Ram owner that pressing on the accelerator while the car is off can screw up the module and throw it into limp mode when it starts up (not the same as my case, because it only happens when I try to engage cruise, but still interesting), and I have pressed the accelerator pedal when the car was off.

 

What did they say? I'm trying to narrow down the wire myself right now.

 

It turned out that the connections to the accel pedal needed to be soldered, because the connectors create a weak (low voltage) connection. I thought it sounded like a pointless thing to do, but they were right. I soldered the wires and everything works.

I'm not a big fan of the way the unit handles maintaining cruise, though. It isn't the smoothest thing ever.

 

I wish someone had told me that before this hack n slash installation! I just road tested it (crimps not solder) and it does not hold speed correctly. Sometimes it holds it 5mph over, sometimes it races up to 100mph if I don't disengage it. Any suggestions?

 

Yikes, mine will over-accelerate about 4mph, and that is annoying. It also goes straight to 75% throttle when it wants to catch up to speed (say, on a hill), rather than gradually increasing the throttle. This means it drops 2 gears instead of one at a time (automatic transmission).