0329745 JOHNSON COVER, Thermostat stbd.

Table 1
Diagnostic Codes Table
CDL Code and Description Conditions which Generate this Code System Response
91-8 Throttle Position Sensor abnormal frequency, pulse width, or period The Electronic Control Module (ECM) detects an incorrect frequency on the throttle signal or an incorrect duty cycle on the throttle signal.
This code is used when the parameter for the "Desired Speed Input Configuration" is configured to "PWM". The code is logged. The ECM flags the throttle position as invalid data and a default value is used. The engine speed may be limited to high idle. The Electronic Control Module (ECM) can be configured to receive three different types of throttle signals for the engine throttle control:"CAN Input" - A J1939 signal is received via the CAN data link."PWM" - The Pulse Width Modulated signal (PWM) must be received via terminal P1-66 at the ECM connector. If direct fuel control mode is used on the engine, the PWM signal must be received via terminal P1-66 at the ECM connector.The signals must be present at the respective inputs in order for the signals to be received by the ECM.For using an electronic external governor for engine control, the "Direct Fuel Control Mode" parameter must be enabled. The ECM input at P1-66 must be used for direct fuel control of the engine. Refer to Troubleshooting, "Direct Fuel Control Mode - Test" for details.For information on these parameters, refer to Troubleshooting, "Configuration Parameters". The ECM will utilize the signal that is defined as the primary throttle as long as a valid signal is available from the expected source. If the signal from the primary throttle becomes unavailable, the ECM will use the signal that is defined as the secondary throttle. If both throttle signals become unavailable, the ECM uses the rated speed of the engine as the setpoint for the desired engine speed.From the factory, the ECM is configured to receive the primary throttle via the CAN data link (J1939 broadcast). The secondary throttle is configured at terminal P1-66 of the ECM connector (PWM signal). The speed control provides a PWM signal for the secondary throttle at this location.Two available throttle signals are unused for this application. Refer to Illustration 1. The second is the inputs for the analog throttle at terminal P2-40 primary ECM and P2-16 secondary ECM.
Illustration 1 g03018817
Schematic of the circuit for the speed control
Illustration 2 g02985256
Terminal locations at the P1 ECM connector for the speed control
(P1-66) Throttle 1 (pri. & sec.)
(P1-1) Throttle 2 (pri. & sec.)
Illustration 3 g02985297
Terminal locations at the P2 ECM connector for the speed control
(P2-92) Analog throttle
Table 2
Troubleshooting Test Steps Values Results
1. Inspect the Electrical Connectors and the Wiring
A. Turn the main disconnect switch to the OFF position.
B. Thoroughly inspect connectors (P1), and (P2). Inspect all of the connectors in the harness from the engine interface connector to the speed control that are associated with the circuit. Refer to Troubleshooting, "Electrical Connectors - Inspect" for details.
C. Perform a 45 N (10 lb) pull test on each of the wires in the ECM connectors, the engine interface connector, and the connector for the EMCP that are associated with the circuit.
D. Check the torque of the allen head screws for each of the ECM connectors. Refer to Troubleshooting, "Electrical Connectors - Inspect" for the correct torque values.
E. Check the harness and the wiring for abrasion and for pinch points from the batteries to the ECM.
Connectors
Results: The connectors and wiring appear to be OK.
Proceed to Test Step 2
Results: The connectors and/or wiring are not OK.
Repair: Repair the wiring and/or the connectors. Replace parts, if necessary.
Verify that the repair eliminates the problem.
2. Check for Active Diagnostic Codes
A. Connect Caterpillar Electronic Technician (ET) to the service tool connector.
B. Restore the electrical power to the ECM.
C. Monitor the active diagnostic code screen on Cat ET. Check for an active 08 code for the throttle signal.
Note: Wait at least 30 seconds in order for the diagnostic codes to become active.
D. Turn the main disconnect switch to the OFF position.
Codes
Results: No diagnostic codes are active.
Repair: If the above code has been logged, there may be an intermittent problem in the harness or in a connector. Refer to Troubleshooting, "Electrical Connectors - Inspect" in order to troubleshoot intermittent electrical problems.
If a problem with the speed control circuit is suspected, proceed to Test Step 3
Results: A 08 diagnostic code is active at this time. The ECM has detected an erratic signal at the input for the throttle signal.
Proceed to Test Step 3
3. Check the Supply Voltage to the Speed Control
A. Restore the electrical power to the ECM.
B. Start the engine.
C. Measure the voltage between terminals +15 and −16 at the speed control.
D. Stop the engine. Turn the main disconnect switch to the OFF position.
24 3.0 VDC
Results: The engine started and the supply voltage is 24 3.0 VDC at the speed control. The speed control is receiving supply voltage.
Proceed to Test Step 4
Results: The supply voltage is not 24 3.0 VDC.
Repair: The supply voltage is not reaching the speed control. If the engine started, the control relay is receiving electrical power. There is a problem in the harness or the connectors between the output of control relay and the speed control. The problem may be in the ground circuit to the speed control.
Perform the following Test Steps:
1. Remove the electrical power from the ECM.
2. Remove the wire from the −Battery terminal at the speed control.
3. Check the resistance between the wire for the −Battery at the speed control and the battery negative post.
The correct measurement will indicate that a short circuit condition exists for the circuit.
If the resistance measurement indicates a short circuit, the ground circuit for the speed control is OK. There is a problem in the harness or the connectors between the control relay and the speed