Electronic Malfunction Light

[mcotter]

I have a 2002 CL713 with a Mack 460, the electronic malfunction light will flash on and off at times while driving but will not while setting still. I had it checked out for codes and came back with engine position sensor problem. I changed it but still have the light flashing on and off at times. when this happens, driver says he can hear a slight change in engine sound and slight loss of power when this happens. Other than that truck runs great. I'm not much of a electronic guru but just need to pointed in the right direction. any thoughts or answers on this problem is greatly appreciated.

[turckster]

SB-221-037.pdf

From the MACK EIS Website:

Failure Mode Identifier (FMI): 2 (Data Erratic/Incorrect) or 8 (Abnormal Frequency)

Parameter Identification (PID): S21

Message Identification (MID): 128

Circuit Description: The Engine Position (EP) Sensor is an inductive device. As the camshaft turns, the tip of the Engine Position (EP) Sensor senses the seven holes in the camshaft drive gear and sends a series of voltage pulses to the Engine Electronic Control Unit (EECU). The frequency of the pulses is translated into engine speed and position by the EECU. The EECU uses this information along with the information from Engine Speed/Timing (RPM/TDC) Sensor to synchronize fuel injection.

Location: The Engine Position (EP) Sensor is located on the lower right front of the engine, in the timing gear cover.

Code Setting Conditions: If the Engine Electronic Control Unit (EECU) senses a significant difference between the engine speed calculated from the Engine Position (EP) Sensor signal and the engine speed calculated from the Engine Speed/Timing (RPM/TDC) Sensor for 2 seconds, the EECU will turn on the Electronic Malfunction Light, and code 3-4 will set. If the signals return to normal for 2 seconds, the code will become inactive. The engine must be running to set an active Engine Position (EP) Sensor fault code.

Electrical problems can cause this fault to be generated, and electrical diagnostics are provided in this section. Mechanical problems can also cause temporary or permanent speed signal errors. After all electrical possibilities have been ruled out, check mechanical conditions that could cause vibration or signal errors. Such conditions include but are not limited to:

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  Faulty Engine Vibration Damper

  
  
  
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  Contaminated sensor tips

  
  
  
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  Contaminated Cam Gear face

  
  
  
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  Excessive Camshaft end play

  
  
  
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  Improperly adjusted sensor

  
  
  
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  Improperly balanced engine components

  
  
  
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  Faulty engine timing cover

  
  
  
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  Improper Camshaft-to-Crankshaft timing

  
  
  

Refer to Service bulletin SB-221-037 for procedures to diagnose mechanical causes of code 3-4.

Before replacing the engine timing cover in an attempt to rectify an intermittent code 3-4, install the Engine Electronic Control Unit (EECU) in another truck built to similar specifications. Road test the other truck and check for code 3-4. If code 3-4 logs in the EECU while installed in the second truck, replace the EECU with a new one and retest the system.

Service Bulletin SB-221 037 has troubleshooting tips for an intermittent 3-4 fault (engine position sensor)

[mcotter]

Thanks for the information, We recently discovered that we can keep the light lit with the throttle pedal at one certain point. Driver was playing with it and made it happen several times so we are leaning towards a new electronic throttle pedal now as it does seem to have different levels of power with pedal in same area at times.

[HarryBiron093]

My otter what did you find to be the problem ? 

[Joey Mack]

That post is 8 years old..  just letting you know..