CUP 8F3709 - Caterpillar

Table 2
Required Tools Qty
146-4080 Digital Multimeter Gp 1
7X-1710 Multimeter Probe 1
326-4904 Adapter Cable As 1
Table 3
Troubleshooting Test Steps Values Results
1. Check for Codes
A. Connect Cat® Electronic Technician (ET) to the service tool connector.
B. Determine if a code is active or logged.
Codes
Result: A 28-3, 974-5 code is active or logged.
Proceed to Test Step 4.
Result: A 28-4, 974-6 code is active or logged.
Proceed to Test Step 5.
Result: A 29 or 91 code is active or logged.
Proceed to Test Step 2.
2. Check the Signal Frequency and the Duty Cycle at the Sensor
A. Turn the keyswitch to the OFF position.
B. Remove the wire from terminal location C (Throttle position) on the wiring harness side of the connector for the throttle position sensor.
C. Install a 326-4904 Adapter Cable As (3-PIN BREAKOUT) at the connector for the throttle position sensor.
D. Connect the connector for the throttle position sensor.
E. Turn the keyswitch to the ON position.
F. Measure the frequency and the duty cycle at the 326-4904 Adapter Cable As (3-PIN BREAKOUT) between the following terminals:
- B (Digital return) and C (Throttle position)
G. Operate the throttle pedal while making the measurements.
H. Turn the keyswitch to the OFF position.
J. Remove the breakout harness.
K. Restore the wiring harness connector to the original configuration.
Frequency
Duty cycle
Result: The Electronic Control Module (ECM) detects an incorrect frequency on the throttle signal or an incorrect duty cycle on the throttle signal. The frequency is below 150 Hz or the frequency is above 1000 Hz. The duty cycle is less than 5 percent or the duty cycle is greater than 95 percent.
Proceed to Test Step 3.
Result: The frequency and the duty cycle are within specifications for the entire range of the pedal.
Repair: Repair or replace the wiring harness.
If the problem is not resolved, proceed to Test Step 3.
3. Check the Supply Voltage to the Sensor
A. Turn the keyswitch to the OFF position.
B. Disconnect the wiring harness connector for the throttle position sensor.
C. Measure the voltage across the following wiring harness connector terminals:
- Terminal A (8 V supply) and Terminal B (Digital return)
7.5 VDC
Result: The supply voltage is above 7.5 VDC at the sensor connector.
Repair: The wiring is OK. Replace the sensor.
Verify that the repair eliminated the problem.
Result: The supply voltage is not above 7.5 VDC at the sensor connector.
The supply voltage is not reaching the speed control.
Repair: Repair or replace the wiring harness.
Verify that the repair eliminated the problem.
4. Create a Short at the Throttle