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cumminsdr, Mechanic
Category: Medium and Heavy Trucks
Satisfied Customers: 3691
Experience:  All types of Cummins applications
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We have a check engine light on in our 2008 peterbuilt isx cummins. How do we check to see

Customer Question

We have a check engine light on in our 2008 peterbuilt isx cummins. How do we check to see the fault code?
The speedometer stopped working, the cruise did and it is running very rough.
Submitted: 2 years ago.
Category: Medium and Heavy Trucks
Expert:  cumminsdr replied 2 years ago.
Hello and welcome to Just Answer! I would be more than happy to assist you today. The battery disconnect does nothing to clear faults, On the dash you should have a diag screen that will show the active faults present. If he fault is inactive than it will not show. In this case Cummins Insite diagnostic tool is required to pull the faults.
Customer: replied 2 years ago.
No all it shows is that there is an engine check light.
Expert:  cumminsdr replied 2 years ago.
Try key on and put cruise switch on hold Acel/decl or set/resume to flash the code out. It should blink @@@ pause @@ [email protected] that would indicate fault 321. You may have a DIAG switch that will flash the code as well. The code will only flash when active. Other than that you will need Cummins Insite to retrieve the fault
Customer: replied 2 years ago.
We didn't get any blinks and we don't have a diag switch
Expert:  cumminsdr replied 2 years ago.
Is the fault active?
Customer: replied 2 years ago.
You mean the check engine light and yes the check engine light is on
Expert:  cumminsdr replied 2 years ago.
Use the following procedure to retrieve the flash codes if the engine is equipped with a diagnostic lamp:
1. Turn the ignition key to the ON position/Engine off.
2. Turn the cruise control ON/OFF switch to the OFF position.
3. Move the SET/RESUME switch to either position. Hold that position until the yellow lamp begins to flash
Here is the operations manual
Expert:  cumminsdr replied 2 years ago.
Fault Code: 241
PID: P084
SPN: 84
FMI: 2/2
LAMP: Amber
Wheel-Based Vehicle Speed - Data Erratic, Intermittent or Incorrect. The ECM lost the vehicle speed signal.
Engine speed limited to Maximum Engine Speed without VSS parameter value. Cruise control, Gear-Down Protection, and Road Speed Governor will not work
The vehicle speed sensor senses the speed of the tailshaft gear on the vehicle's transmission. This speed signal is then transmitted to the engine electronic control module (ECM) and converted into a vehicle speed.
The vehicle speed sensor is located in the rear of the vehicle transmission. The trans tone wheel may also be loose causing this fault. and a trans repair shop would be required to replace the tone wheel.
This fault is set active when the ECM loses a vehicle speed signal when other engine conditions indicate the vehicle is moving. The fault can also become active if there is a series of clutch, service brake or throttle movements with no vehicle movement. The fault is set inactive when the ECM receives a vehicle speed signal greater than zero.
Expert:  cumminsdr replied 2 years ago.
Hello just following up. Do you need more assistance?Please don't forget to rate my service.
Expert:  cumminsdr replied 2 years ago.
Please don't forget to rate my service.