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Electronic Control System Gas Plus Engines – FAULT CODE 753 – B and C Gas Plus

Engine Position Sensor Synchronization Error

Overview

CODE REASON EFFECT
Fault Code: 753
PID: 21
SPN: 636
FMI: 2
LAMP: Amber
SRT: 

Engine Speed/Position – Camshaft Synchronization Error. Invalid engine speed signal detected on the engine position sensor signal pins in the ECM.

Engine can possibly die or will
not start.

Engine Position Sensor Circuit
SMALL | MEDIUM | LARGE

Circuit Description

The engine position sensor monitors the engine speed and position, then passes this information to the electronic control module (ECM) through the sensor harness.

Component Location

The engine position sensor is located in the gear housing, above the air compressor.

Shop Talk

The engine position sensor is a magnetic sensor and senses the raised material on the back of the camshaft gear to determine engine position and speed. There are seven raised material pieces on the back of the camshaft gear, one for each cylinder and one for timing.

Cautions and Warnings

 CAUTION 

To reduce the possibility of pin and harness damage, use the following test lead when taking a measurement:
Part Number 3823996 – female Weather Pack™ test lead.

Troubleshooting Steps

STEPS SPECIFICATIONS
STEP 1. Check the fault codes.  
  STEP 1A. Read the fault codes. Fault Code 753 active?
STEP 2. Check the engine position sensor.  
  STEP 2A. Inspect the engine harness and engine position sensor connector pins. Dirty or damaged pins?
  STEP 2B. Inspect the sensor for damage. Damage found?
  STEP 2C. Check the resistance of the sensor. 1000 to 2000 ohms?
  STEP 2D. Check for a short circuit to ground. Greater than 100k ohms?
  STEP 2E. Read the fault codes. Fault Code 753 active?
  STEP 2F. Verify adequate camshaft speed/position sensor air gap. Distance is between 33.81 mm [1.33 in] and 34.06 mm [1.34 in]?
STEP 3. Clear the fault codes.  
  STEP 3A. Disable the fault code. Fault Code 753 inactive?
  STEP 3B. Clear the inactive fault codes. All fault codes cleared?

Guided Step 1 – Check the fault codes.

Guided Step 1A – Read the fault codes.

Conditions

  • Turn keyswitch ON.
  • Connect INSITE™ electronic service tool.

Action

Read the fault codes.

Use INSITE™ electronic service tool to read the fault codes.

Fault Code 753 active?
YES NO
No Repair No Repair

Guided Step 2 – Check the engine position sensor.

Guided Step 2A – Inspect the engine harness and engine position sensor connector pins.

Conditions

  • Turn keyswitch OFF.
  • Disconnect engine harness connector 1 from the ECM.

Action

Inspect the engine harness and engine position sensor connector pins for the following:

  • Loose connector
  • Corroded pins
  • Bent or broken pins
  • Pushed back or expanded pins
  • Moisture in or on the connector
  • Missing or damaged connector seals
  • Dirt or debris on or in the connector pins
  • Connector shell broken
  • Wire insulation damage
  • Damaged connector locking tab.

Use the following procedure for general inspection techniques.
Refer to Procedure 019-361 in Section 19.

Dirty or damaged pins?
YES NO

Repair the damaged pins. Replace the engine harness, or replace the sensor, whichever has the damaged pins.

 No Repair

Guided Step 2B – Inspect the sensor for damage.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the engine harness from the engine position sensor.

Action

Inspect the engine position sensor for the following:

  • Metal debris on end of sensor
  • Damage to end of sensor caused by the engine gear
  • Oil leakage or insulation problems such as swelling
  • Damaged electrical potting in sensing end of sensor.

Damage found?
YES NO

Replace the sensor.
Refer to Procedure 019-038 in Section 19.

Inspect the camshaft tone wheel/gear teeth for damage or spinning. For B Series engines, use the following procedure in the B5.9G, B5.9LPG, B Gas Plus, B LPG Gas Plus Engines Troubleshooting and Repair Manual, Bulletin 3666164.
Refer to Procedure 001-013 in Section 1. For C Series engines, use the following procedure in the C8.3G, C Gas Plus and L Gas Plus Engines Troubleshooting and Repair Manual, Bulletin 3666206.
Refer to Procedure 001-013 in Section 1.

No Repair

Guided Step 2C – Check the resistance of the sensor.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the engine harness from the engine position sensor.

Action

Check the resistance of the sensor.

  • Measure the resistance from the engine position sensor SIGNAL pin to the engine position sensor RETURN pin in the engine position sensor connector.
  • Measure the resistance from the engine position backup SIGNAL pin to the engine position backup RETURN pin in the engine position sensor connector.

Refer to the circuit diagram or wiring diagram for connector pin identification.

Use the following procedure for general resistance measurement techniques.
Refer to Procedure 019-360 in Section 19.

SMALL | MEDIUM | LARGE

1000 to 2000 ohms?
YES NO
No Repair

Replace the sensor.
Refer to Procedure 019-038 in Section 19.

Guided Step 2D – Check for a short circuit to ground.

Conditions

  • Turn keyswitch OFF.
  • Disconnect the engine harness from the engine position sensor.
  • Engine position sensor is installed.

Action

Check for a short circuit to ground.

  • Measure the resistance from the SIGNAL pin in the engine position sensor connector, sensor side, to the engine block ground.
  • Measure the resistance from the backup SIGNAL pin in the engine position sensor connector, sensor side, to the engine block ground.

Refer to the circuit diagram or wiring diagram for connector pin identification.

Use the following procedure for general resistance measurement techniques.
Refer to Procedure 019-360 in Section 19.

SMALL | MEDIUM | LARGE

Greater than 100k ohms?
YES NO
No Repair

Repair or replace the sensor.

Guided Step 2E – Read the fault codes.

Conditions

  • Connect all components.
  • Turn keyswitch ON.
  • Connect INSITE™ electronic service tool.

Action

Read the fault codes.

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to read the fault codes.

Fault Code 753 active?
YES NO
No Repair

The removal and installation of the connector corrected the failure.

Guided Step 2F – Verify adequate camshaft speed/position sensor air gap.

Conditions

  • Turn keyswitch OFF.
  • Remove camshaft speed/position sensor from the engine.

Action

Verify adequate air gap.

  • Measure the distance between the sensor o-ring sealing surface and the edge of the tone wheel.
SMALL | MEDIUM | LARGE

Distance is between 33.81 mm [1.33 in] and 34.06 mm [1.34 in]?
YES NO
No Repair

Inspect the camshaft tone wheel/gear teeth for damage or spinning. For B Series engines, use the following procedure in the B5.9G, B5.9LPG, B Gas Plus, B LPG Gas Plus Engines Troubleshooting and Repair Manual, Bulletin 3666164.
Refer to Procedure 001-013 in Section 1. For C Series engines, use the following procedure in the C8.3G, C Gas Plus and L Gas Plus Engines Troubleshooting and Repair Manual, Bulletin 3666206.
Refer to Procedure 001-013 in Section 1.

Guided Step 3 – Clear the fault codes.

Guided Step 3A – Disable the fault code.

Conditions

  • Connect all components.
  • Turn keyswitch ON.
  • Connect INSITE™ electronic service tool.

Action

Disable the fault code.

  • Start the engine and let it idle for one minute.
  • Use INSITE™ electronic service tool to verify that Fault Code 753 is inactive.

Fault Code 753 inactive?
YES NO
No Repair

Troubleshooting procedures need to be repeated from the beginning.

Guided Step 3B – Clear the inactive fault codes.

Conditions

  • Connect all components.
  • Turn keyswitch ON.
  • Connect INSITE™ electronic service tool.

Action

Clear the inactive fault codes.

  • Use INSITE™ electronic service tool to erase the inactive fault codes.

All fault codes cleared?
YES NO
No Repair

Troubleshoot any remaining active fault codes.
Repair complete
Appropriate troubleshooting charts
Last Modified:  27-Apr-2010
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Published by Jack

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