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Daniel Wilson
Daniel Wilson,
Category: Medium and Heavy Trucks
Satisfied Customers: 5409
Experience:  Owner at DJ Wilson
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My 2003 Navistar dt530e has a two speed switch to operate

Customer Question

my 2003 Navistar dt530e has a two speed switch to operate throttle. switch is new. I need to know how the engine with electric throttle is controlled to operate by a toggle switch and how to troubleshoot it..
Submitted: 1 year ago.
Category: Medium and Heavy Trucks
Expert:  Pete replied 1 year 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.

I see no one has posted any help with this here.In some cases this can be due to the info you may be looking for may be difficult to obtain or the correct person that can help may not be online.

Usually the throttle switch sends a signal to the engine computer and then the engine computer then operates the throttle motor.On some models there is an actual throttle control ecu and in this case the throttle signal would be sent to this ecu instead.

Unfortunately I do not have the diagnosis of this to test the signals but on some models you can check the signals using a compatible scan tool to read the data signals from the throttle sensor/accelerator sensor to see if it is sending a correct signal as well as read the commanded output signal on the scan tool to see if the computer is sending the correct signal,this would usually indicate both of these are o.k. if they are sending the correct signals and that the fault can be with the throttle motor itself.Any seen sending an incorrect signal would indicate it as the cause here.

I apologize and wish I had more testing info on this here for you but unfortunately this is all I have on this and wanted to post so you knew your question was seen.

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 1 year ago.
Thanks for the reply but no. The ecu on this engine is controlled externally by a one volt input reference to raise rpm. There is a remote run harness installed that allow relay protected signal..i was hoping for wire identification to bypass such installation to test ecm response to force an increase in rpm..thanks..
Expert:  Pete replied 1 year ago.

Unfortunately this is all of the info I have on this here myself.Would you like me to open your question up for others here to see if anyone else can assist further on this?

Let me know,thanks Pete

Customer: replied 1 year ago.
i need a navistar tech to ask..thanks..
Expert:  Pete replied 1 year ago.

No problem.

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 1 year ago.

Hi, my name is***** you get this resolved or do you still need help with this? Let me know and I will be glad to try to help as well as get you the troubleshooting information you need. Let me know the chassis model this engine is in and what functions you want to control with the remote throttle as far as what you have installed on the chassis that you are controlling such as a ramp truck, hydraulic crane, etc. ?

Customer: replied 1 year ago.
Hi dan.. thanks for the reply..i have a2003 7400 chassis. My question is the remote harness must have some safety interlocks wired in..since allthe wires are on grey and violet. I wondered what safety features are connected. Im missing battery voltage to the remote high idle switch that exits the remote throttle harness. Since only four of the 20 purple wires are used for the throttle, obviously something may be locking out the throttle as a safety preventive measure.
Expert:  Daniel Wilson replied 1 year ago.

Thanks for the info. Lets start with getting you the schematics for this truck. Click on the links below.

Schematic 1

Schematic 2

Schematic 3

Expert:  Daniel Wilson replied 1 year ago.

The last schematic link is the connector composites which are referenced in 1 and 2 links I posted

Expert:  Daniel Wilson replied 1 year ago.

This covers the OEM side of the circuit and ECM pinouts. Also there is some ECM and body controller programming involved for that circuit as well to match the setup you have. As far as some of the other wiring, that will be depending on the installer of what you are installing for a remote throttle kit and may not be covered in the OEM schematics. What is installed on this truck?

Expert:  Daniel Wilson replied 1 year ago.

Is this a firetruck?

Customer: replied 1 year ago.
This is a firetruck. The remote harness is factory.
Expert:  Daniel Wilson replied 1 year ago.

thanks for the update. Let me know if you need more help once you have reviewed the diagrams. I log in as time allows in between jobs etc.