G3600 A4 Engines Speed Control - Test Caterpillar


Speed Control - Test
`

Use this procedure to troubleshoot a problem with the throttle position sensor. Also, use this procedure if one of the following diagnostic codes is active or easily repeated.

Table 1
J1939 Code and Description  Comments 
29-3
Accelerator Pedal Position #2 : Voltage Above Normal 
The Electronic Control Module (ECM) detects signal voltage that is not in the acceptable range.
The ECM flags the throttle position as invalid data and a default value is used. The engine speed is limited to high idle.
The code is logged. 
29-4
Accelerator Pedal Position #2 : Voltage Below Normal 
The ECM detects signal voltage that is not in the acceptable range.
The ECM flags the throttle position as invalid data and a default value is used. The engine speed is limited to high idle.
The code is logged. 
91-3
Accelerator Pedal Position #1 : Voltage Above Normal 
The ECM detects signal voltage that is not in the acceptable range.
The ECM flags the throttle position as invalid data and a default value is used. The engine speed is limited to high idle.
The code is logged. 
91-4
Accelerator Pedal Position #1 : Voltage Below Normal 
The ECM detects signal voltage that is not in the acceptable range.
The ECM flags the throttle position as invalid data and a default value is used. The engine speed is limited to high idle.
The code is logged. 
91-8
Accelerator Pedal Position #1 : Abnormal Frequency, Pulse Width, or Period 
The ECM detects signal voltage that is not in the acceptable range.
The ECM flags the throttle position as invalid data and a default value is used. The engine speed is limited to high idle.
The code is logged. 
974-5
Remote Accelerator Pedal Position : Current Below Normal 
The code is logged. 
974-6
Remote Accelerator Pedal Position : Current Above Normal 
The code is logged. 

For this troubleshooting procedure, the desired speed input configuration parameter can be set to 4 mA to 20 mA input, PWM input, or 0 V to 5 V input. The Electronic Control Module (ECM) will only monitor the status of the input signal for the PWM and 0 V to 5 V desired speed inputs. The ECM does not supply the power and ground for the PWM or 0 V to 5 V speed control circuits.

If using the Operator Control Panel (OCP) 0 V to 5 V analog output or the PWM speed control feature, then the OCP will monitor the status of those outputs in relation to power and ground circuit health. If an external speed control source device is used, refer to that devices troubleshooting procedure. If using the OCP CAN desired speed input, refer to troubleshooting procedure Troubleshooting, Data Link-Test.

The value of the current, frequency, or voltage corresponds to a range of desired engine speeds between minimum high idle and maximum high idle. The "Minimum Engine High Idle Speed" and the "Maximum Engine High Idle Speed" are set with the "Service/Configuration" screen of Cat® Electronic Technician (ET). For more information, refer to Troubleshooting, Configuration Parameters.

When the idle/rated speed switch is in the RATED position, a current value of 4.0 mA, 5 percent duty cycle, or 0.5 V corresponds to the programmed "Minimum Engine High Idle Speed". A current value of 20.0 mA, 95 percent duty cycle, or 4.5 V corresponds to "Maximum Engine High Idle Speed". Current values within this range will vary the desired engine speed in a linear fashion between. The range will vary between "Minimum Engine High Idle Speed" and "Maximum Engine High Idle Speed".



Illustration 1g06026342
PWM circuit


Illustration 2g06026354
mA and V circuit

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 the connectors. Refer to Troubleshooting, "Electrical Connectors-Inspect" for additional information.

C. Perform a 45 N (10 lb) pull test on the connector wires.

D. Check the harness for abrasions and pinch points.
 

Connectors and Wiring
 

Result: The connectors and wiring appear to be OK.

Proceed to Test Step 2.

Result: There is a problem with the connectors and/or wiring.

Repair: Repair or replace the connectors or wiring. Ensure that all the seals are properly in place and ensure that the connectors are coupled.

If the problem is not resolved, proceed to Test Step 2.
 

2. 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 29-3, 91-3, or 91-8 code is active or logged.

Proceed to Test Step 3.

Result: A 974-5 code is active or logged.

Proceed to Test Step 4.

Result: A 29-4, 91-4, or 974–6 code is active or logged.

Proceed to Test Step 5.
 

3. Check the Wiring for an Open Circuit

A. Turn the main disconnect switch to the OFF position.

B. Remove the signal wire at the Engine Interface Connector (EIC) that supplies the PWM or analog 0 V to 5 V desired speed input signal to the Electronic Control Module (ECM).

C. Disconnect the P1 and P2 connector from the ECM.

D. Measure the resistance across the following wiring harness connector terminals:

- A 29-3 code: ECM P2-94 and Terminal 15 (customer connector terminal block #1
- A 91-3 or 91-8 code: ECM P1-66 and Terminal 66 (customer connector terminal block #1
 

Open Circuit
 

Result: There are less than 10 ohms of resistance.

Repair: The wiring is OK. There may be a problem with the speed control signal after the customer connector. For information on, refer to the Original Equipment Manufacturers (OEM) service information.

If the problem is not resolved , proceed to Test Step 5

Result: There were more than 10 ohms of resistance.

Repair: An open circuit has been detected. Repair or replace the wiring harness.

Verify that the repair eliminated the problem.
 

4. Check the Wiring for an Open Circuit

A. Turn the main disconnect switch to the OFF position.

B. Remove the wires for the desired speed and the return from terminal strip terminals 85 and 86. Install a jumper wire between the wires for the desired speed and the return that were removed from the terminal strip.
 

Open Circuit
 

Result: The jumper wire was detected by the ECM. A 974-6 code is active.

Repair: The wiring is OK. There may be a problem with the speed control signal after the customer connector. For information on, refer to the Original Equipment Manufacturers (OEM) service information.

Verify that the repair eliminated the problem.

Result: The ECM did not detect the short circuit.

Repair: There is a wiring problem between the terminal strip and ECM. Repair or replace the wiring harness.

Verify that the repair eliminated the problem.
 

5. Check the Wiring for a Short Circuit to Battery

A. Turn the main disconnect switch to the OFF position.

B. Disconnect the wiring harness from the speed control device.

C. Check the voltage between the disconnected wires for the speed control device and the battery (-).
 

Short Circuit
 

Result: There was not battery voltage between the battery (+) and speed control device terminals at the wiring harness connector.

Proceed to Test Step 6.

Result: There was battery voltage between the battery (+) and speed control device terminals at the wiring harness connector.

Repair: Repair or replace the wiring harness.

Verify that the repair eliminated the problem.
 

6. Check the Wiring for a Short Circuit

A. Turn the main disconnect switch to the OFF position.

B. Disconnect the wiring harness from the ECM and EIC.

C. Measure the resistance between the ground strap for the ECM and following wiring harness connector pins:

- A 29–4 code: ECM P2-94 and Ground strap
- A 91–4 or 91-8 code: ECM P1-66 and Ground strap
- A 974-6 code: ECM P2-89 and Ground strap
- A 974-6 code: ECM P2-90 and Ground strap
 

Short Circuit
 

Result: There are more than 100K ohms between the ECM terminal and engine ground.

Proceed to Test Step 7.

Result: There are less than 100K ohms between the ECM terminal and engine ground.

Repair: There is a short circuit in the wiring harness. Repair or replace the wiring harness.

Verify that the repair eliminated the problem. 

7. Check the Device that Provides the Desired Engine Speed Signal

A. Measure the desired engine speed signal , refer to the Original Equipment Manufacturer (OEM) service information. Verify that the correct signal is being provided to the ECM.

B. Verify that the desired engine speed signal is present at the following ECM terminals for the type of desired speed input being utilized:

- A 29-3 or 29-4: ECM P2-94
- A 91-3, 91-4, or 91-8: ECM P1-66
- A 974-5 or 974-6: ECM P2-89 and P2-90
 

Signal
 

Result: The desired engine speed signal is correct.

Repair: There appears to be a problem with the ECM. Perform the following procedure:

1. Temporarily connect a test ECM.

Refer to Troubleshooting, "ECM - Replace" for additional information.

2. Recheck the circuit to ensure that the original problem is resolved.

If the problem is resolved with the test ECM, reconnect the suspect ECM. If the problem returns with the suspect ECM, replace the ECM. Verify that the problem is resolved.

If the problem is not resolved with the test ECM, install the original ECM. There is a problem in the wiring.

3. Before returning the engine to service, clear the logged diagnostic codes that are associated with this test.

Result: The desired engine speed signal is not correct.

Repair: There is probably a problem with the device that provides the desired engine speed input signal. Service the device that provides the desired engine speed input signal, refer to the OEM service information.

Verify that the repair eliminated the problem.
 

If the procedure did not correct the issue, contact your Cat dealer Technical Communicator (TC). For further assistance, your TC can confer with the Dealer Solutions Network (DSN).

Information System:

Remanufactured Oil Pumps May Have a Shallow Suction Tube Port on Certain 3400 Engines{1304}
2013/12/03 New Software Is Used On Certain G3500B Engines {1901, 1902, 1920}
G3600 A4 Engines Air/Fuel Pressure Module - Test - G3616
G3600 A4 Engines Air/Fuel Pressure Module - Calibrate
G3600 A4 Engines Oil Filter Differential Pressure Problem
C11 and C13 Engines Turbocharger
C11 and C13 Engines Muffler
G3306B Generator Sets Overhaul (Major)
2013/12/18 A New Valve Cover Base and Wiring Harnesses Are Now Used on Certain C27 and C32 Engines {1120, 1408}
12M Series 3, 140M Series 3, 160M Series 3, 140, 150 and and 160 Motor Graders Hydraulic Fan Speed - Calibrate and Adjust
12M Series 3, 140M Series 3, 160M Series 3, 140, 150 and and 160 Motor Graders Hydraulic Fan Speed - Test
C280-08 Marine Engine Catalyst (SCR) - Replace
G3600 A4 Engines Temperature Ratio of Coolant to Oil Is Low
C280-12 Marine Engine Maintenance Interval Schedule
140, 150, 160, 12M Series 3, 140M Series 3 and 160M Series 3 Motor Graders Lifting and Tying Down the Machine
12M Series 3, 140M Series 3, 160M Series 3, 140, 150 and and 160 Motor Graders Brake Accumulator Charging Valve - Check
3516C Locomotive Engines Selective Catalytic Reduction Data Link - Test
C280-16 Marine Engines Engine Oil - Change
3516C Locomotive Engines Selective Catalytic Reduction Sensor Signal (Analog, Active) - Test
C280-08 Marine Engine Exhaust Inlet Nitrogen Oxide Sensor - Replace
3516C Locomotive Engines Selective Catalytic Reduction Solenoid Valve - Test
Procedure to Rework the Pump for the Water Delivery System (WDS){5070}
C4.4 and C7.1 Engines Ether Starting Aid - Test
12M Series 3, 140M Series 3, 160M Series 3, 140, 150 and and 160 Motor Graders Brake Control Valve (Service) - Check