41656T Mercruiser GEAR, (16/27)

Table 1
Diagnostic Trouble Codes for the Digital Throttles
J1939 Code CDL Code Code Description
(code descriptions may vary) Comments
29-3 774-3 Accelerator Pedal Position 2 : Voltage Above Normal The Electronic Control Module (ECM) detects the following conditions:
The ECM has been powered for 3 seconds.
Diagnostic code 168-4 is not active.
There are no active 678 or 41 codes.
The setting for the upper diagnostic limit has been exceeded for one second.
If equipped, the warning lamp will come on. The diagnostic code will be logged.
29-4 774-4 Accelerator Pedal Position 2 : Voltage Below Normal The ECM detects the following conditions:
The ECM has been powered for 3 seconds.
Diagnostic code 168-4 is not active.
There are no active 678 or 41 codes.
The setting for the lower diagnostic limit has been exceeded for one second.
If equipped, the warning lamp will come on. The diagnostic code will be logged.
29-8 774-8 Accelerator Pedal Position 2 : Abnormal Frequency, Pulse Width or Period The ECM detects the following conditions:
The signal frequency from the digital throttle position sensor is equal to 0% or 100% for more than 2 seconds.
The ECM has been powered for at least 3 seconds.
Diagnostic codes 29-3 (774-3) or 29-4(774-4) are not active.
There are no active 678 or 41 codes.
The ECM sets the Throttle Position to "0%".
If equipped, the warning lamp will come on. The diagnostic code will be logged if the engine is running. The diagnostic code will not be logged if the engine is cranking.
91-3 91-3 Accelerator Pedal Position 1 : Voltage Above Normal The Electronic Control Module (ECM) detects the following conditions:
The ECM has been powered for 3 seconds.
Diagnostic code 168-4 is not active.
There are no active 678 or 41 codes.
The setting for the upper diagnostic limit has been exceeded for one second.
If equipped, the warning lamp will come on. The diagnostic code will be logged.
91-4 91-4 Accelerator Pedal Position 1 : Voltage Below Normal The ECM detects the following conditions:
The ECM has been powered for 3 seconds.
Diagnostic code 168-4 is not active.
There are no active 678 or 41 codes.
The setting for the lower diagnostic limit has been exceeded for one second.
If equipped, the warning lamp will come on. The diagnostic code will be logged.
91-8 91-8 Accelerator Pedal Position 1 : Abnormal Frequency, Pulse Width or Period The ECM detects the following conditions:
The signal frequency from the digital throttle position sensor is equal to 0% or 100% for more than 2 seconds.
The ECM has been powered for at least 3 seconds.
Diagnostic codes 91-3 and 91-4 are not active.
There are no active 678 or 41 codes.
The ECM sets the Throttle Position to "0%".
If equipped, the warning lamp will come on. The diagnostic code will be logged if the engine is running. The diagnostic code will not be logged if the engine is cranking. If a fault occurs with the primary throttle, the engine will use the secondary throttle until the fault is repaired.If a fault occurs with the secondary throttle, the engine will use the primary throttle until the fault is repaired.If a functional throttle is not available, the following conditions will occur:
The engine will default to the limp home speed.
If the engine speed is higher than the limp home speed, the engine will decelerate to the limp home speed.
If the engine speed is lower than the limp home speed, the engine speed will remain at the current speed.
The engine will remain at this speed while the diagnostic code remains active.
All inputs from the faulty throttle are ignored by the ECM until the fault is repaired.
All inputs from the repaired throttle will be ignored by the ECM until the keyswitch has been cycled.Digital Throttle Position SensorThe digital throttle position sensor is used to provide a digital throttle position signal to the ECM. The sensor output is a constant frequency signal with a pulse width that varies with the throttle position. This output signal is referred to as either a duty cycle or a pulse width modulated signal (PWM). This output signal is expressed as a percentage between 0 and 100 percent.The digital throttle position sensor is most likely to be attached directly to the throttle assembly. The digital throttle position sensor requires no adjustment.The duty cycle at low idle and the duty cycle at high idle can vary depending on the application. The percent of duty cycle is translated in the ECM into a throttle position of 3 to 100 percent.The digital throttle position sensors are powered by +8 VDC from the ECM. The supply voltage is from J1: to the digital throttle position sensor connector.If the application is using the ECM dedicated PTO functions, the digital throttle position sensor will be ignored while the engine is in PTO mode.The ECM is in PTO mode if the PTO ON/OFF Switch is ON. This status can be checked with the