Medium and Heavy Trucks
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Thanks for asking your question. I will try and help you out.
Does the yellow check engine light on when the engine is running?
Can you get me the engine serial number please? Or the year model?
Thanks for the information.
128 indicates there is an engine diagnostic code. Unfortunately there is not a code 034-7 on the code list for this engine.
If the red engine warning light is coming on. There are several codes that will turn the red light on.
Low oil pressure warning
High coolant temp warning
Low coolant level
Low intake valve actuation pressure.
Vehicle speed out of range.
To confirm you can pull the flash codes by using the cruise control switches. If you have never done this before. Here is how.
Use the following procedure to retrieve the flash codes from the check engine light: Turn the ignition key switch to the On position/ Engine OFF.Turn the cruise control ON/OFF switch to the OFF position.Move the SET/RESUME switch to either position. Hold that position until the yellow lamp begins to flash.The yellow lamp will flash in order to indicate a two digit flash code and the SET/RESUME switch may be released. The sequence of flashes represents the system diagnostic message. Count the first sequence of flashes in order to determine the first digit of the flash code. After a two second pause, the second sequence of flashes will identify the second digit of the flash code. Any additional flash codes will follow after a pause. These codes will be displayed in the same manner. Flash Code 55 indicates that No Detected Faults have occurred since the ignition key switch has been turned to the ON position.
Let me know what two digit code you get and I can tell you what the problem is.
I would assume the 34-7 is for another item not the engine. As that is not an engine code.
If the code retrieval does not work with the cruise switches. Then the next step would be to connect a service tool to read the ECM. I am sorry. I wish there was another way.