8M2001502 Mercruiser CLAMP

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, 29-4, and 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.
Follow the troubleshooting procedure to identify the root cause of the fault. 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 electronic service tool. Refer to Troubleshooting, "Power Take-Off - Test" for testing if the PTO is being used.Note: The identification letters for the terminals in the connectors may vary dependent on the manufacturer of the throttle pedal.
Illustration 1 g06104803
Table 2
Required Tools
Tool Part Number Part Description Qty
A 326-4904 Adapter Cable As 1 During the following procedure, refer to the electrical schematic for the application.Complete the procedure in the order in which the steps are listed.
Table 3
Troubleshooting Test Steps Values Results
1. Inspect Electrical Connectors and Wiring
A. Thoroughly inspect the terminal connections on the P1/J1 ECM connector and the PWM throttle position sensors. Refer to Troubleshooting, "Electrical Connector - Inspect".
B. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connector and the PWM throttle position sensor connector.
C. Check the screw for the ECM connector for the correct torque of 6 N m (53 lb in).
D. Check the harness for corrosion, abrasion, and pinch points from the PWM throttle position sensor to the ECM.
Loose connection or damaged wire
Result: There is a fault in a connector or the wiring.
Repair: Repair any faulty connectors or replace the wiring harness. Ensure that all the seals