906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Speed Sensor

Speed Sensor - Test

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System [UENR5036]

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Sensor Signal (PWM) - Test

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Sensor Supply - Test

ELECTRICAL AND STARTING SYSTEM

SENSOR GP

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Sensor Signal (Analog, Active) - Test

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Sensor Signal (Analog, Passive) - Test

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Sensor Signal (PWM) - Test

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Speed Sensor - Test

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Sensor Supply - Test

906K, 906M, 907K, 907M, 908K and 908M Compact Wheel Loaders Electrohydraulic System Calibration

1.1. Machine ECM

2.1. Diagnostic Trouble Code Procedure

Machine ECM

The following is a list of Diagnostic Trouble Codes (DTCs) that are associated with the speed sensors of the machine.

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Table 1
Machine ECM (MID 71)
DTC	Code Description	System Response
190-8	Engine Speed Sensor: Abnormal frequency, pulse width, or period	Machine drive will be inoperable.
3271-8	Drive Motor Speed Sensor #1 Signal Line #1: Abnormal frequency, pulse width, or period	Machine speed is greatly limited.
3272-8	Drive Motor Speed Sensor #1 Signal Line #2: Abnormal frequency, pulse width, or period	Machine speed is greatly limited.

Possible causes for an FMI 8 diagnostic code are:

The sensor has failed.
The spacing of the sensor is incorrect.
Intermittent connections or poor connections.
Mechanical devices are loose.
Incorrect software is loaded to the ECM.
The ECM has failed. ECM failure is unlikely.

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Illustration 1	g03714765
Schematic of the Speed Sensors

Note: The diagram above is a simplified schematic of the Machine ECM and the Speed Sensor connections. The schematic is electrically correct. However, not all of the possible harness connectors are shown. Refer to the latest revision of Electrical Schematic, UENR5407 for prefixes: L66, L77, L88, or Electrical Schematic, UENR5408 for prefixes: Z66, Z77, Z88, or Electrical Schematic, UENR5409 for prefixes: H66, H77, H88.

Diagnostic Trouble Code Procedure

Note: Prior to beginning this procedure, inspect the harness connectors that are involved in this circuit. Poor connections can often be the cause of a problem in an electrical circuit. Verify that all connections in the circuit are clean, secure, and in good condition. If a problem with a connection is found, correct the problem and verify that the diagnostic code is active before performing a troubleshooting procedure.

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Table 2
Troubleshooting Test Steps	Values	Results
1. Identify The Active FMI Code Associated With The Sensor Supply Circuit	Code present.	FMI 8 diagnostic code, proceed to Test Step 2.
Begin Process For FMI 8 Troubleshooting HERE
2. Check The Speed Sensor Circuits For An Open A. Turn the key switch and the disconnect switch to the OFF position. B. Disconnect the sensor from the ECM. C. Disconnect the J1 and J2 wire harness from the ECM. D. At the harness connector for the sensor, place a jumper wire between the signal contact and the supply contact. E. At machine harness connector for ECM, measure the resistance from the signal contact the supply contact.	There should be continuity (less than 5.0 Ω resistance)	OK -The resistance measurement is less than 5 ohms. The resistance measurement for the speed sensor circuits is not indicating that there is an open circuit or a poor connection in the speed sensor circuits between the ECM and the speed sensor. Proceed to Test Step 3. NOT OK - The resistance measurement is greater than 5 Ω at all times or the resistance measurement is greater than 5 Ω part of the time during the manipulation of the circuit wiring. There is an open circuit or a poor connection in one of the speed sensor circuits Repair:Repair or replace the machine harness Proceed to Test Step 4.
3. Check The Speed Sensor Signal Circuit For A Short Remove the jumper between contact 1 and contact 2 for the machine harness connector for the speed sensor B. Reconnect the speed sensor to the machine harness C. At the J1 and J2 harness connectors, measure the resistance between speed sensor power and all possible sources of positive voltage and ground D. Repeat the previous Test Step for the speed sensor return contact	Each resistance should be greater than 4 kΩ	OK -The machine harness is correct Proceed to Test Step 4 NOT OK -One or more of the individual resistance measurements is less than 4000 Ω. There is a short circuit between either frame ground or another circuit in the cab harness. Repair:Repair or replace the machine harness Proceed to Test Step 4.
4. Check If The Diagnostic Code Remains A. Inspect the harness connectors and clean the contacts of the harness connectors. B. Reconnect all harness connectors. C. Turn key switch and disconnect switch ON. D. Operate the machine. E. Check if diagnostic code is active.	Diagnostic code is no longer present.	OK - Diagnostic code does not exist at this time. Initial diagnostic code may have been caused by poor electrical connection or short at one of the harness connections. Resume machine operation. STOP NOT OK - Diagnostic trouble code has not been corrected. If the diagnostic code has not been corrected after performing the procedure a second time, the ECM may require replacement. Prior to replacing this component, always contact the Technical Communication at your dealership for possible consultation with AVSpare. This consultation may greatly effect repair time. Follow the steps in Troubleshooting, "Electronic Control Module (ECM) - Replace" if the ECM needs to be replaced. STOP