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Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 4398
Experience:  Owner at DJ Wilson
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I have a 1999 freightliner century with Detroit 60 and

Customer Question

I have a 1999 freightliner century with Detroit 60 and optimized idle. Cruise will not work while I idle. Cruise works while driving, but must manually turn off before slowing down or shifting. Also cruise control will not turn off if you press brake or clutch or shift to neutral, instead of turning off it actually does the opposite and try's to rev faster.
Submitted: 10 months ago.
Category: Medium and Heavy Trucks
Expert:  Pete replied 10 months ago.

My name is ***** ***** I am a professional here at Just Answer. I noticed that your question had not received a response and thought I would see if you still need help with this.I apologize for the delay and I hope I can still assist you with this here.My info is somewhat limited on your model here but I had seen no one else has responded and would like to see if I can help here.If at any time you feel that I cannot help with this please let me know.

This can be due to a number of different components causing this fault here.The clutch pedal switch or brake switch sending incorrect signals can cause this needing replaced.There are also some issues on some of these models with some air switches that can fail on the air system manifold needing replaced.Some models use these switches in conjunction with the cruise control system.

What needs to be done is to have the fault codes read out of all computers to see what codes are set.Once this has been done any codes set will need to be diagnosed to locate and repair this fault here.This needs done using a scan tool or computer that will plug into your vehicle and can communicate with all computers.

If more help is needed, use the reply tab to continue our conversation. If no further assistance is needed, kindly rate my service.You can rate at any time and we can continue to work on your question as this will not close out your question.Keep in mind in some cases it can be difficult to fully diagnose or help repair your vehicle without seeing it and I work on delivering the best possible answer from what I see to work with.

Thanks Pete

Customer: replied 10 months ago.
There is no fault codes.
Expert:  Pete replied 10 months ago.

O.k.,this may be an issue with an air switch failure or one of the clutch or brake pedal switches as these are common for this fault here.Unfortunately I dont have the testing procedure for this here to test these but they will need tested.If you want I can open your question up for others here to see if anyone else can assist further on this just let me know if this is something you would like to do.

Thanks Pete

Customer: replied 10 months ago.
That's great. My question was originally intended for "Budnshe". When I asked the question I was reading another reply from another mechanic. And it seemed like he had a lot of knowledge about the cruise control with optimized idle. So when I asked the question I thought I was asking him directly.
Expert:  Pete replied 10 months ago.

Lets see if he can help here.

I will open your question up for others here to see if someone else can assist further on this as there may be others here that may have more info on what to check or do with this issue.I hope you can get this resolved with ease.No need to reply to my last post here unless it is a last resort as it will keep your question locked to me and others will not be able to view it.If you feel you want to continue to work with me on this feel free to reply at any time but keep in mind in some cases it can be difficult to fully diagnose or help repair this without seeing your vehicle.

Thanks Pete

Expert:  Daniel Wilson replied 10 months ago.

Hello Ace, My name is***** will be glad to help you with this... Under the dash there is an air manifold with your pressure switches both normally open and closed so be careful when replacing any switches you get the correct one.. very common error as they look alike. Check the harness and connections to the switches and also test the switches with an ohm meter for continuity. I will post the diagram to identify your switches

Expert:  Daniel Wilson replied 10 months ago.

Here is your diagram

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