480-1970 Position Sensor Gp (Synchro) Troubleshooting on 966 and 972 XE Medium Wheel Loader, Event Codes E1289, E1290, E1291 {1408, 1439, 3065, 3168, 7324, 7400, 7856} Caterpillar

Wheel Loader

966K Series XE (S/N: NGX1-UP)

966M Series XE (S/N: FL21-UP; P6C1-UP; B8P1-UP)

972M Series XE (S/N: L9S1-UP; M5S1-UP; EDW1-UP)

Introduction

The problem that is identified below does not have a known permanent solution. Until a permanent solution is known, use the temporary solution that is identified below.

Problem

Higher machine to machine variation has been seen with the latest position sensor design (480-1970), which is causing event codes to be falsely generated on some machines. Event codes include E1289, E1290, and E1291.

Solution

This TIB will cover any potential issues arising from installing the new 480-1970 Position Sensor Gp along with the software available in PS45662. It does not apply to the original 291-2529 Position Sensor As, which can use the troubleshooting available in Troubleshooting , UENR3826.

Report the failure through the CPI feedback tool in Service Information Management System (SIMSi) referencing CPI number 409810 to have a Send-It-Back (SIB) request generated. A SIB request will be issued to your Dealer code in the SIB system after the SIMSi entry is created.

For specific repair instructions, refer to the following rework procedure.

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Do not operate or work on this product unless you have read and understood the instruction and warnings in the relevant Operation and Maintenance Manuals and relevant service literature. Failure to follow the instructions or heed the warnings could result in injury or death. Proper care is your responsibility.

Rework Procedure

General Terminology

The position sensor’s primary purpose is to verify that each synchronizer is in the correct position prior to engaging/disengaging clutches and moving between ranges. They also ensure that the transmission does not get into a scenario which can damage itself by allowing a mechanical tie up or allow excessive wear on the actuating forks. The software will take various actions based on the feedback of each position sensor, which may include locking out a speed range or neutralizing the transmission for safety reasons.

The software continuously monitors the positions and looks for each synchronizer to be either in a neutral or engaged state. The clutch shaft synchronizers (LoF/HiR or LoR HiF) have a neutral boundary of +/- 2 mm. The auxiliary synchronizer neutral boundary is -2.5 mm (travel only in 1 direction). If the synchronizer comes from an engaged position and is not able to reach the neutral trigger point, the synchronizer fails to reach neutral. If the synchronizer was in the neutral position and shifts away from the neutral trigger, the synchronizer has violated neutral.

The clutch shaft synchronizers have an engaged trigger value of +/- 11 mm. The auxiliary synchronizer engaged trigger value is -10 mm. If the synchronizer cannot reach the trigger point, the synchronizer fails the engagement. If the synchronizer was in an engaged position and drifts back to either +/- 8 mm (clutch shaft synchronizers) or -6.5 mm (auxiliary synchronizer), the synchronizer has walked out (loss of mechanical connection). If the synchronizer position is above +/- 14 mm (clutch shaft synchronizers) or -16 mm (auxiliary synchronizer), the synchronizer is in an overly engaged state.

All of the above scenarios are captured as events in the software. An event tied to LoF/HiR is covered in E1289-2. LoR/HiF is covered in E1290-2 and Aux is covered in E1291-2. The below graphics are a visualization of the key working conditions and trigger points.

Illustration 1	g06275261
Clutch Shaft Synchronizers Key Values (LoF/HiR & LoR/HiF)

Illustration 2	g06275273
Planetary Shaft Synchronizer Key Values (Aux)

General Troubleshooting Steps

1. Download PSR & EDT file prior to flashing latest software.

   1. Send to product support if unable to resolve after completing the troubleshooting.

2. Check for active or logged E1289-2, E1290-2, or E1291-2 event codes.

   1. After performing the remaining general steps, review each event code to determine the specific scenario that is causing the problem based on the data log information.

      1. If no event codes are active or logged and you feel there is a shift hesitation, review E1289 for LoF & HiR, E1290 for LoR & HiF, or E1291 for Aux.

3. Check the suction screen magnets for debris.

4. Set-up a custom group in ET to capture the following parameters:

   1. Transmission Input Speed

   2. Transmission Planetary Speed #1

   3. Transmission Output Speed #1

   4. Transmission Output Speed #2

   5. Transmission Synchronizer #1 Position Sensor Duty Cycle (C)

   6. Transmission Synchronizer #2 Position Sensor Duty Cycle (C)

   7. Transmission Synchronizer #3 Position Sensor Duty Cycle (C)

   8. Transmission Oil Temperature

   9. Transmission Hydrostatic Loop A Pressure

   10. Transmission Hydrostatic Loop B Pressure

   11. Transmission Hydrostatic Speed Ratio

   12. Desired Transmission Output Torque

   13. Actual Gear

   14. Directional Switch Position

   15. Accelerator Pedal Position

   16. Brake/Decelerator Pedal Position

   17. Ground Speed / Direction

5. Warm up the machine to more than 60° C (140 ° F) transmission oil temperature and record an ET data log while operating the machine in each range (forward and reverse). If possible, operate the machine in a stock pile or loading ramp of at least 6% grade.

   1. Operating on a stock pile or loading ramp will help ensure the aux position can maintain a confirmed neutral state. If not, the transmission will neutralize if it is violated and generate an E1291 event code.

6. Review the ET data log and check the synchro positions for acceptance.

   1. Normal position sensor values on a flat surface
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      Table 1

      Synchro Position	MIN, %DC	MAX, %DC	MIN< mm	MAX, mm
      LoF/HiR Neutral	47.1	56.6	-2.0	2.0
      LoR/HiF Neutral	47.1	56.6	-2.0	2.0
      LoF Engaged	20.5	25.0	-12.8	-11.0
      HiF Engaged	77.0	82.0	10.9	13.1
      Aux Off*	56.0	48.4	-2.5	2.5
      Aux On	73.0	67.5	-13.6	-10.0
      LoR Engaged	20.5	25.0	-12.8	-11.0
      HiR Engaged	77.0	82.0	10.9	13.1
      *Check on a min. 6% grade if possible. If not, target 54.5% (-1.5 mm) on flat.

7. After reviewing the data log, refer to the below section on potential scenarios and specific resolution steps.

8. If actions are taken, rerun a data log and look for changes in the synchronizer position values compared to the first data log that was recorded to verify the fix is valid.

Event Code Troubleshooting Steps

E1289 – LoF/HiR Synchronizer Not Responding (Possible Scenarios)

1. LoF is overly engaged (Synchronizer <17.6% DC, <-14 mm)

   1. If position is ≤10% DC, replace the position sensor (SIB if resolved).

   2. If position is between 10.1% DC and 17.6% DC, check LoF on/off valve for functionality.

   3. If valve is ok, replace the position sensor (SIB if resolved).

   4. If still not resolved, rerun data log, download new EDT file, and contact product support.

2. LoF Engagement Will Not Confirm (Synchronizer cannot reach 25% DC, -11 mm)

   1. If position is between 25%DC and 32% DC, replace the position sensor (SIB if resolved).

   2. If position is between 32.1% DC and 56.5% DC, key cycle and run the machine again.

      1. If event code reoccurs for this reason, check the actuating pistons and seals for damage.

   3. If position is between 56.6% DC and 89.9% DC, check wiring for faults.

   4. If position is ≥ 90% DC, replace the position sensor (SIB if resolved).

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

3. LoF Fails to Reach or Violates Confirmed Neutral (Synchronizer < 47.1% DC or > 56.6% DC, < -2 mm or > +2 mm).

   1. If position is ≤ 10% DC or ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. If position is >10% DC and <32% DC, key cycle and run the machine again.

      1. If the event code reoccurs, check the actuating pistons and seals for damage.

      2. If Ok, then check the LoF & HiR on/off valves and synchronizer modulating valve to ensure they are functionality properly.

   3. If position is between 32.1% DC and 47% DC, check the LoF & HiR on/off valves and synchronizer modulating valve to ensure they are functioning properly.

   4. If position is between 56.7% DC and 89.9% DC, check the HiR on/off valve for functionality and check for wiring faults.

   5. If the above did not resolve, replace the position sensor (SIB if resolved).

   6. If still not resolved, rerun data log, download new EDT file, and contact product support.

4. LoF Walks Out (Synchronizer position increases to > 32.3% after confirming the engagement, > -8 mm)

   1. If position is ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. Check the HiR on/off valve to ensure there is no residual pressure forcing it out of gear.

   3. If the valve is functioning properly, replace the position sensor (SIB if resolved).

   4. If still not resolved, rerun data log, download new EDT file, and contact product support.

5. LoF Synchro Clashing Due to Early Engagement Confirmation (Shift Hesitation / Noise)

   1. If shifts into LoF seem excessive (hesitation > 1 sec) or if you hear a grinding/ratcheting noise when going into the range, review the engagement in the data log to look for clashing of the synchronizer teeth. The position trace will look jagged due to the teeth ratcheting against each other.

      1. The below plot shows an example of 3 LoF engagements which all engaged. The green curve in the 3^rd plot from the top shows a clashing event. Synchronization should occur before -5.5mm, if it is lower and there are erratic steps in the position, it is clashing. Total engagement time at operating temp should not exceed 300ms.
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         Illustration 3	g06275258

      2. If clashing is detected, replace the position sensor (SIB if resolved).

   2. If still not resolved, rerun data log, download new EDT file, and contact product support.

      1. Note that if it is not resolved, continuing to operate in this condition will produce internal transmission damage. If you cannot wait for feedback, install 291-2529 Position Sensor As in all 3 locations until further assistance can be provided (NACD & EAME product support has a limited number of 291-2529 Position Sensor As available.

6. LoF Position Sensor is Out of Range (Synchronizer ≤ 10% DC or ≥ 90% DC)

   1. Check for electrical faults.

   2. If no faults detected, replace the position sensor (SIB if resolved).

   3. If above did not resolve, rewire sensor directly from ECM.

   4. If not resolved, replace ECM.

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

7. HiR Overly Engaged (Synchronizer >84.0% DC, >14 mm).

   1. If position is ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. If position is between 84.1% DC and 89.9% DC, check HiR on/off valve for functionality.

   3. If valve is ok, replace the position sensor (SIB if resolved).

   4. If still not resolved, rerun data log, download new EDT file, and contact product support.

8. HiR Engagement Not Confirmed (Synchronizer cannot reach 77.2% DC, 11 mm).

   1. If position is ≤ 10% DC, replace the position sensor (SIB if resolved).

   2. If position is between 10.1% DC and 47.0% DC, check wiring for faults.

   3. If position is between 47.1% DC and 69.9% DC, key cycle and run the machine again.

      1. If event code reoccurs for this reason, check the actuating pistons and seals for damage.

   4. If position is between 70% DC and 77.1% DC, replace the position sensor (SIB if resolved).

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

9. HiR Fails to Reach or Violates Confirmed Neutral (Synchronizer < 47.1% DC or > 56.6% DC, <-2 mm or >2 mm)

   1. If position is ≤ 10% DC or ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. If position is >10% DC and <47% DC, check the LoF on/off valve for functionality and wiring faults.

   3. If position is between 56.7% DC and 70% DC, check the LoF & HiR on/off valves and synchronizer modulating valve to ensure they are functioning properly.

   4. If position is between 70.1% DC and 89.9% DC, key cycle and run the machine again.

      1. If the event code reoccurs, check the actuating pistons and seals for damage.

      2. If Ok, then check the LoF & HiR on/off valves and synchronizer modulating valve to ensure they are functionality properly.

   5. If the above did not resolve, replace the position sensor (SIB if resolved).

   6. If still not resolved, rerun data log, download new EDT file, and contact product support.

10. HiR Walks Out (Synchronizer position decreases to < 70.3% after confirming the engagement, <8 mm)

    1. If position is ≤ 10% DC, replace the position sensor (SIB if resolved).

    2. Check the LoF on/off valve to ensure there is no residual pressure forcing it out of gear.

    3. If the valve is functioning properly, replace the position sensor (SIB if resolved).

    4. If still not resolved, rerun data log, download new EDT file, and contact product support.

11. HiR Synchro Clashing Due to Early Engagement Confirmation (Shift Hesitation / Noise).

    1. If shifts into HiR seem excessive (hesitation > 1 sec) or if you hear a grinding/ratcheting noise when going into the range, review the engagement in the data log to look for clashing of the synchronizer teeth. The position trace will look jagged due to the teeth ratcheting against each other.

       1. Refer to the example in Step 5.a.a above. Synchronization should occur below 5.5 mm. If it is higher and there are erratic steps in the position, it is clashing. Total engagement time at operating temp should not exceed 300ms.

       2. If clashing is detected, replace the position sensor (SIB if resolved).

    2. If still not resolved, rerun data log, download new EDT file, and contact product support.

       1. Note that if it is not resolved, continuing to operate in this condition will produce internal transmission damage. If you cannot wait for feedback, install 291-2529 Position Sensor As in all 3 locations until further assistance can be provided (NACD & EAME product support has a limited number of 291-2529 Position Sensor As available).

12. HiR Position Sensor is Out of Range (Synchronizer ≤ 10% DC or ≥ 90% DC)

    1. Check for electrical faults.

    2. If no faults detected, replace the position sensor (SIB if resolved).

    3. If above did not resolve, rewire sensor directly from ECM.

    4. If not resolved, replace ECM.

    5. If still not resolved, rerun data log, download new EDT file, and contact product support.

E1290 – LoR/HiF Synchronizer Not Responding (Possible Scenarios)

1. LoR Overly Engaged (Synchronizer <17.6% DC, <-14 mm)

   1. If position is ≤10% DC, replace the position sensor (SIB if resolved).

   2. If position is between 10.1% DC and 17.6% DC, check LoR on/off valve for functionality.

   3. If valve is ok, replace the position sensor (SIB if resolved).

   4. If still not resolved, rerun data log, download new EDT file, and contact product support.

2. LoR Engagement Not Confirmed (Synchronizer can’t reach 25% DC, -11 mm)

   1. If position is between 25%DC and 32% DC, replace the position sensor (SIB if resolved).

   2. If position is between 32.1% DC and 56.5% DC, key cycle and run the machine again.

      1. If event code reoccurs for this reason, check the actuating pistons and seals for damage.

   3. If position is between 56.6% DC and 89.9% DC, check wiring for faults.

   4. If position is ≥ 90% DC, replace the position sensor (SIB if resolved).

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

3. LoR Fails to Reach or Violates Confirmed Neutral (Synchronizer < 47.1% DC or > 56.6% DC, <-2 mm or > 2 mm)

   1. If position is ≤ 10% DC or ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. If position is >10% DC and <32% DC, key cycle and run the machine again.

      1. If the event code reoccurs, check the actuating pistons and seals for damage.

      2. If Ok, then check the LoR & HiF on/off valves and synchronizer modulating valve to ensure they are functionality properly.

   3. If position is between 32.1% DC and 47% DC, check the LoR & HiF on/off valves and synchronizer modulating valve to ensure they are functioning properly.

   4. If position is between 56.7% DC and 89.9% DC, check the HiF on/off valve for functionality and check for wiring faults.

   5. If the above did not resolve, replace the position sensor (SIB if resolved).

   6. If still not resolved, rerun data log, download new EDT file, and contact product support.

4. LoR Walks Out (Synchronizer position increases to > 32.3% after confirming the engagement, >-8mm)

   1. If position is ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. Check the HiF on/off valve to ensure there is no residual pressure forcing it out of gear.

   3. If the valve is functioning properly, replace the position sensor (SIB if resolved).

   4. If still not resolved, rerun data log, download new EDT file, and contact product support.

5. LoR Synchro Clashing Due to Early Engagement Confirmation (Shift Hesitation / Noise)

   1. If shifts into LoR seem excessive (hesitation > 1 sec) or if you hear a grinding/ratcheting noise when going into the range, review the engagement in the data log to look for clashing of the synchronizer teeth. The position trace will look jagged due to the teeth ratcheting against each other.

      1. For example, refer to LoF in the E1289 Step 5.a.a. Synchronization should occur before -5.5 mm, if it is lower and there are erratic steps in the position, it is clashing. Total engagement time at operating temp should not exceed 300ms.

      2. If clashing is detected, replace the position sensor (SIB if resolved).

   2. If still not resolved, rerun data log, download new EDT file, and contact product support.

      1. Note that if it is not resolved, continuing to operate in this condition will produce internal transmission damage. If you cannot wait for feedback, install 291-2529 Position Sensor As in all 3 locations until further assistance can be provided (NACD & EAME product support has a limited number of 291-2529 Position Sensor As available).

6. LoR Position Sensor is Out of Range (Synchronizer ≤ 10% DC or ≥ 90% DC)

   1. Check for electrical faults.

   2. If no faults detected, replace the position sensor (SIB if resolved).

   3. If above did not resolve, rewire sensor directly from ECM.

   4. If not resolved, replace ECM.

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

7. HiF Overly Engaged (Synchronizer >84.0% DC, >14 mm)

   1. If position is ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. If position is between 84.1% DC and 89.9% DC, check HiF on/off valve for functionality.

   3. If valve is ok, replace the position sensor (SIB if resolved).

   4. If still not resolved, rerun data log, download new EDT file, and contact product support.

8. HiR Engagement Not Confirmed (Synchronizer cannot reach 77.2% DC, 11 mm).

   1. If position is ≤ 10% DC, replace the position sensor (SIB if resolved).

   2. If position is between 10.1% DC and 47.0% DC, check wiring for faults.

   3. If position is between 47.1% DC and 69.9% DC, key cycle and run the machine again.

      1. If event code reoccurs for this reason, check the actuating pistons and seals for damage.

   4. If position is between 70% DC and 77.1% DC, replace the position sensor (SIB if resolved).

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

9. HiR Fails to Reach or Violates Confirmed Neutral (Synchronizer < 47.1% DC or > 56.6% DC, <-2 mm or >2 mm)

   1. If position is ≤ 10% DC or ≥ 90% DC, replace the position sensor (SIB if resolved).

   2. If position is >10% DC and <47% DC, check the LoF on/off valve for functionality and wiring faults.

   3. If position is between 56.7% DC and 70% DC, check the LoF & HiR on/off valves and synchronizer modulating valve to ensure they are functioning properly.

   4. If position is between 70.1% DC and 89.9% DC, key cycle and run the machine again.

      1. If the event code reoccurs, check the actuating pistons and seals for damage.

      2. If Ok, then check the LoF & HiR on/off valves and synchronizer modulating valve to ensure they are functionality properly.

   5. If the above did not resolve, replace the position sensor (SIB if resolved).

   6. If still not resolved, rerun data log, download new EDT file, and contact product support.

10. HiR Walks Out (Synchronizer position decreases to < 70.3% after confirming the engagement, <8 mm)

    1. If position is ≤ 10% DC, replace the position sensor (SIB if resolved).

    2. Check the LoR on/off valve to ensure there is no residual pressure forcing it out of gear.

    3. If the valve is functioning properly, replace the position sensor (SIB if resolved).

    4. If still not resolved, rerun data log, download new EDT file, and contact product support.

11. HiF Synchro Clashing Due to Early Engagement Confirmation (Shift Hesitation / Noise).

    1. If shifts into HiF seem excessive (hesitation > 1 sec) or if you hear a grinding/ratcheting noise when going into the range, review the engagement in the data log to look for clashing of the synchronizer teeth. The position trace will look jagged due to the teeth ratcheting against each other.

       1. Refer to the example in E1289, Step 5.a.a. Synchronization should occur below 5.5 mm. If it is higher and there are erratic steps in the position, it is clashing. Total engagement time at operating temp should not exceed 300ms.

       2. If clashing is detected, replace the position sensor (SIB if resolved).

    2. If still not resolved, rerun data log, download new EDT file, and contact product support.

       1. Note that if it is not resolved, continuing to operate in this condition will produce internal transmission damage. If you cannot wait for feedback, install 291-2529 Position Sensor As in all 3 locations until further assistance can be provided (NACD & EAME product support has a limited number of 291-2529 Position Sensor As available).

12. HiF Position Sensor is Out of Range (Synchronizer ≤ 10% DC or ≥ 90% DC)

    1. Check for electrical faults.

    2. If no faults detected, replace the position sensor (SIB if resolved).

    3. If above did not resolve, rewire sensor directly from ECM.

    4. If not resolved, replace ECM.

    5. If still not resolved, rerun data log, download new EDT file, and contact product support.

E1291 – Aux Synchronizer Not Responding (Possible Scenarios)

1. Aux is Overly Engaged (Synchronizer position >76.7% DC, -16 mm)

   1. If position is > 76.7% DC, replace the position sensor (SIB if resolved).

   2. If still not resolved, rerun data log, download new EDT file, and contact product support.

2. Aux Engagement Not Confirmed (Synchronizer can’t reach 67.5% DC, -10mm)

   1. If position is between 62% DC and 67.5% DC, replace the position sensor (SIB if resolved).

   2. If position is between 48.4% DC and 61.9% DC, check the auxiliary synchronizer modulation valve for electrical or functionality issue.

   3. If position is less than 48.4% DC, replace the position sensor (SIB if resolved).

   4. If still not resolved, rerun data log, download new EDT file, and contact product support.

3. Aux Synchro Fails to Reach or Violates Confirmed Neutral (Synchronizer position >56.0% DC, -2.5 mm)

   1. If position is between 56% DC and 58% DC, replace the position sensor (SIB if resolved).

      1. If not resolved, replace the 329-6957 target.

   2. If position is between 58.1% DC and 62% DC or below 48.4%, replace the position sensor (SIB if resolved).

   3. If position is between 62.1% and 76.7% DC, check the auxiliary synchronizer modulation valve for functionality to make sure it is not stuck open.

   4. If position is above 76.6% DC, replace the position sensor (SIB if resolved).

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

4. Aux Synchro Walks Out (Synchronizer position decreases to < 62.2% DC after confirming the engagement, >-6.5 mm)

   1. If position is < 48.4% DC, replace the position sensor (SIB if resolved).

   2. If position is between 48.5% DC and 62.1% DC, check the auxiliary synchronizer modulation valve for functionality.

   3. If not resolved, check the electrical system for faults and ensure pressure is being supplied to the synchronizer modulation valve.

   4. If not resolved, replace the position sensor (SIB if resolved).

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

5. Aux Sensor Out of Range (Synchronizer ≤ 10% DC or ≥ 90% DC)

   1. Check for electrical faults.

   2. If no faults detected, replace the position sensor (SIB if resolved).

   3. If above did not resolve, rewire sensor directly from ECM.

   4. If not resolved, replace ECM.

   5. If still not resolved, rerun data log, download new EDT file, and contact product support.

6. Aux Synchro Clashing Due to Early Engagement Confirmation (Shift Hesitation / Noise)

   1. If shifts into Aux seem excessive (taking more than 1-1.5 seconds) or if you hear a grinding/ratcheting noise when going into aux, review the engagements in the data log to look for clashing of the synchronizer teethtrace will look jagged due to the teeth ratcheting against each other.

      1. See example below, which depicts the sliding sleeve teeth clashing with the clutch body ring (bottom plot, between 10.6 sec and 11.55 sec). At 11.55 sec, the synchro is neutralized and engagement is retried, completing successfully between 11.65 sec and 11.8 sec. The total engagement time at operating temp should not exceed 400ms.
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         Illustration 4	g06275256

      2. If clashing is detected, replace the position sensor (SIB if resolved).

   2. If sensor replacement doesn’t resolve, replace the auxiliary target 329-6957 Target.

   3. If still not resolved, rerun data log, download new EDT file, and contact product support.

      1. Note that if it is not resolved, continuing to operate in this condition will produce internal transmission damage. If you cannot wait for feedback, install 291-2529 Position Sensor As in all 3 locations until further assistance can be provided (NACD & EAME product support has a limited number of 291-2529 sensors available).

         1. If still not resolved, install a dummy 341-6661 Solenoid Valve Gp or 312-8629 Coil to the auxiliary modulation valve connector to prevent the machine from trying to engage auxiliary and limit VG to 3.0.