Hello

Im getting frustrated with the electrical gremlins but I digress. Ive got a 2005 LR3 SE. Over the past year the cruise control would either fail to turn on or disconnect after a short period of time. Ive replaced the clock spring and the switch controls on the steering wheel and brake switch and I continue to have the same issue. And Ive replaced the battery within the last 6 months and the voltage is always above 14.1v. Some days are good and I can enable cruise control and it will work flawlessly while other days dont work at all. I finally found the following error code

P0576-16 (2A) Speed control input - circuit low - General electrical failure - circuit voltage below threshold

As soon as I clear this one error code, I can enable cruise control and I wont have the error return sometimes for hours and other times minutes. Does anyone have any suggestions what I can check or what I can do? Im hoping to get this fixed for road trip season. Thank you guys.

 

I used to have a problem with my cruise control. I noticed that if I turned the key to the on position and let the truck go through all of it's checks before starting the ignition, the cruise would always work as it should. Occasionally, I would hop in and start the truck all at once and when I did that, I would have problems with the cruise control. This may be totally unrelated, but it has worked for me (knock on wood).

 

I have nothing to loss trying it out and will do the next couple times I go for a drive. Thanks for the idea

 

Make certain the wiring harness under the column is properly plugged in. I have seen two cases where the harness itself has been an issue.

 

I can attest to it being fully plugged in both on the old one and even the new one I just bought. I checked the harness itself and it has no breaks and is snug. As soon as I get the error I can clear it and everything is back to normal for a short or long period

 

Which harness did you buy? It has three connectors.

 

Its the harness that connects into the circuit boards for the cruise and audio controls on the steering wheel and then into the new clock spring.

 

Okay, that should be the one. Has a black ground connector also I think. If thats new then it would have to be an issue further down the line. I wonder if a GAP tool can read button inputs.

 

Yup its new and it didnt help or make the issue worse. I really do appreciate the thoughts. The GAP cant read the cruise control lamp and when it fails, it wont turn on the lamp. Ill check later and see if it can show more about buttons, Ive never looked that far. Im not sure if its related or not but nearly every single time I start the LR3, I get a Transmission Fault on the dash for maybe 2 seconds and it goes away. I get no CEL or anything in the codes regarding this and it doesnt effect the LR3 is way but it might be related

 

Ah... trans fault. I bet that is is. Cruise is disabled by list of faults far too long too mention, but it basically expects a perfectly working truck. So any ABD or driveline issues will disable it. If its at startup then its almost always alternator/battery related. I would verify battery voltage before starting. I know you have 14.1 when running which lily indicated the alternator is good BUT does not guarantee its not failing. Alternators start to fail by randomly cutting out and annoyingly the LR3 does not give much of a warning, the battery lights is almost useless. With all that said there is another annoying flaw which is brake lights. One should use proper brake like lamps of good quality as the system is very sensitive to them. When installed the filament should be vertical, if horizontal its the wrong lamp or a poor quality one. So if you have not done the brake lamps in a while, maybe just replace them as another thing to rule out. Certainly cheap and easy to do.