Circuit ISUZU KB P190 2007 Workshop Repair Manual

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-105
B3: Engine Races Up During Starting (Slip)
B4: Large Shock When Selector Lever is Changed from N to D Range or N to R Range
Checks Action
Definition:
The engine speeds up but the vehicle speed does not increase when the accelerator pedal is stepped on at starting.
Diagnosis Hints Slipping of the clutch is suspected. Gear ratio error DTC might be set.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission fluid is
extremely blacked, contaminated or smells burnt, slipping of clutch is suspected.
• Low quantity
• Contamination
•Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure. Refer to
Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Faulty operation of transmission fluid pressure switch. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect any clutch for slipping.
Additional Checks • Inspect the engine for proper outputs. Refer to appropriate inspection chart in
engine section.
• Inspect the TCM grounds for being clean, tight, and in their proper locations.
• Observe the Accelerator Pedal Position (APP). APP parameter should change linearly from 0 to 99 or 100% according to the accelerator pedal operation.
Checks Action
Definition:
A large shock is felt when the selector lever is changed from N to D or N to R during idle.
Diagnosis Hints • Check the vehicle side such as exhaust mounting and engine mounting.
• With the fail-safe operation, garage shock may grow worth. If there is no DTC, faulty operation of the control valve or seized clutch might be suspected.
Transmission Range Switch &
Selector Lever Cable Checks Inspect the transmission range switch and selector lever cable for misadjusting or
disordering. Refer to On-Vehicle Service section.
Line Pressure Test Inspect the line pressure in D range or R range for a possible high or low pressure.
Refer to Line Pressure Test in Test Instruction section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect any clutch for seizing.
Additional Checks • Inspect the transmission input signals.
• Inspect the engine for proper idle speed.
• Inspect the suspension for play.

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ISUZU KB P190 2007

7A2-106 TRANSMISSION CONTROL SYSTEM (JR405E)
B5: Engine Stalls When Selector Lever is Changed from N to R, D, 3, 2 or L Range
B6: Engine Does Not Crank in P or N Range
B7: Engine Cranks in other than P or N Range
B8: Extended Time Lag When Selector Lever is Changed from N to D
Checks Action
Definition:
The engine stalls when selector lever is changed from N or P position to a run position during engine idling.
Diagnosis Hints • As the correct cause is attributable to the engine, faulty idle up, insufficient
engine output, etc. are suspected.
• As this is a cause of the transmission, faulty torque converter clutch (TCC) piston is suspected.
• If the transmission fluid through resistance increases due to clogged oil cooler or some other reason, or if the transmission fluid level decreases, the TCC piston
works causing the engine stall.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission fluid is
extremely blacked, contaminated or smells burnt, slipping of clutch is suspected.
• Low quantity
• Contamination
• Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure. Refer to
Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction
section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking lock up spool valve
• Sticking TCC solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Additional Checks • Inspect the engine for proper outputs. Refer to appropriate inspection chart in
engine section.
• Inspect the engine for proper idle speed.
Checks Action
Definition: • The engine starter does not run even though the P or N range.
• The engine starter runs even though the R, D, 3, 2 or L range.
Transmission Range Switch & Selector
Lever Cable Checks Inspect the transmission range switch and selector lever cable for misadjusting or
disordering. Refer to On-Vehicle Service section.
Checks Action
Definition:
The shift time lag is longer than the standard value when the selector lever is changed from N to D.
Transmission Fluid Checks Inspect the transmission fluid for low quantity.
Line Pressure Checks Inspect the line pressure in D range for a possible dropped pressure. Refer to Line
Pressure Test in Test Instruction section.

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-107
B9: Extended Time Lag When Selector Lever is Changed from N to R
B10: Brake is Applied in R Range
B11: Insufficient Starting or Shaking in D Range
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect the low clutch and low one-way clutch for slipping.
Solenoid Valve Checks • Inspect the low clutch solenoid valve for faulty operation.
Checks Action
Definition:
The shift time lag is longer than the standard value when the selector lever is changed from N to R.
Transmission Fluid Checks Inspect the transmission fluid for low quantity.
Line Pressure Checks Inspect the line pressure in R range for a possible dropped pressure. Refer to Line
Pressure Test in Test Instruction section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect the low & reverse brake for slipping.
Solenoid Valve Checks • Inspect the low & reverse brake solenoid valve for faulty operation.
Checks
Action
Checks Action
Definition:
Brake is applied suddenly in R range.
Diagnosis Hints Trouble in transmission main unit is suspected. The trouble in the transmission main
unit may originate from the input circuits or output circuits; these circuits should also
be checked to prevent a reoccurrence of the trouble.
Transmission Range Switch & Selector
Lever Cable Checks Inspect the transmission range switch and selector lever cable for misadjusting or
disordering. Refer to On-Vehicle Service section.
Transmission Fluid Checks Inspect the transmission fluid for low quantity.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect the low clutch, high clutch or 2-4 brake for seizing.
Additional Checks • Inspect the parking mechanism for faulty operation.
Checks Action
Definition:
Insufficient starting or shaking in D range.
Transmission Fluid Checks Inspect the transmission fluid for low quantity.
Line Pressure Checks Inspect the line pressure in D range for a possible dropped pressure. Refer to Line
Pressure Test in Test Instruction section.

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ISUZU KB P190 2007

7A2-108 TRANSMISSION CONTROL SYSTEM (JR405E)
B12: Noise or Vibration Occurs at Starting
C1: Engine Race Up (Slipping) When Gearshift is Up from 1st to 2nd
C2: Engine Race Up (Slipping) When Gearshift is Up from 2nd to 3rd
C3: Engine Race Up (Slipping) When Gearshift is Up from 3rd to 4th
C4: Engine Race Up (Slipping) When Gearshift is Down from 4th to 3rd
C5: Engine Race Up (Slipping) When Gearshift is Down (or Kick-down) from 4th to 2nd
C6: Engine Race Up (Slipping) When Gearshift is Down (or Kick-down) from 3rd to 2nd
C7: Engine Race Up (Slipping) When Gearshift is Down (or Kick-down) from 4th or 3rd to 2nd
C8: Engine Race Up (Slipping) Others
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect the low clutch, reverse clutch, low one-way clutch or low & reverse brake for
slipping.
Checks
Action
ChecksAction
Definition:
Noise or vibration occurs in the vicinity of the transmission at starting.
Diagnosis Hints Cause other than transmission is suspected. Reproduce the running condition using
a lift up, chassis dynamo, etc. to investigate the origin of the noise and vibration.
Additional Checks • Inspect the differential gear noise.
• Inspect the propeller shaft noise.
• Inspect the tires for unbalanced or poor uniformity.
Checks Action
Definition: • Engine speed-up occurs when the accelerator pedal is stepped on for acceleration, and the gear is shifted up.
• Engine speed-up occurs when the accelerator pedal is stepped on for acceleration, and the gear is shifted down or for kick-down during steady run.
• Engine speed-up occurs when the accelerator pedal is stepped on for acceleration, and the gear is shifted down or for kick-down during steady run.
Diagnosis Hints Slipping of the clutch is suspected. Gear ratio error DTC might be set.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission fluid is
extremely blacked, contaminated or smells burnt, slipping of clutch is suspected.
• Low quantity
• Contamination
•Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure. Refer
to Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction
section.

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-109
C9: Braking Feel When Gearshift is Up from 1st to 2nd
C10: Braking Feel When Gearshift is Up from 2nd to 3rd
C11: Braking Feel When Gearshift is Up from 3rd to 4th
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Faulty operation of transmission fluid pressure switch. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect any clutch for slipping.
Additional Checks • Inspect the engine for proper outputs. Refer to appropriate inspection chart in
engine section.
• Inspect the TCM grounds for being clean, tight, and in their proper locations.
• Observe the Accelerator Pedal Position (APP). APP parameter should change linearly from 0 to 99 or 100% according to the accelerator pedal operation.
Checks Action
Definition:
A braking feeling occurs when the accelerator pedal is stepped on for acceleration, and the gear is shifted up.
Diagnosis Hints Slipping of the clutch is suspected. Gear ratio error DTC might be set.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission fluid is
extremely blacked, contaminated or smells burnt, slipping of clutch is suspected.
• Low quantity
• Contamination
• Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure. Refer to
Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction
section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Faulty operation of transmission fluid pressure switch. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect any clutch for slipping.
Additional Checks • Inspect the engine for proper outputs. Refer to appropriate inspection chart in
engine section.
• Inspect the TCM grounds for being clean, tight, and in their proper locations.
• Observe the Accelerator Pedal Position (APP). APP parameter should change linearly from 0 to 99 or 100% according to the accelerator pedal operation.
Checks
Action

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-111
D2: Gearshift Frequently
Diagnosis Hints• When inspecting faulty gear shifting, it is important to distinguish between
the fault of the electric system and transmission main unit.
• Fault of electric system. - Monitor the output signal (each solenoid driving signal) using a scan tool. If a trouble signal is sent to the solenoid synchronously with the faulty
gear shifting, the fault is originated in the electric system.
- Monitor the input signal (signal from each sensor) using a scan tool and find an input signal which has an output signal (each solenoid driving
signal) subjected to a fault.
- Fault of the electric system may be derived from temperature or vibration. For instance, although the engine is normal while it is cold, fault may
occur when the engine is warmed up or the vehicle is running.
• Fault of mechanical system. - If the gear is incorrectly shifted, irrespective of the operating signal (On/ Off) of each solenoid, the fault is originated from the transmission main
unit.
- If the clutch slips, or the transmission fluid smells burnt or is contaminated or black, or the stall speed increases. Gear ratio error DTC might be set.
Transmission Range Switch & Selector
Lever Cable Checks Inspect the transmission range switch and selector lever cable for misadjusting
or disordering. Refer to On-Vehicle Service section.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission fluid
is extremely blacked, contaminated or smells burnt, slipping of clutch is
suspected.
• Low quantity
• Contamination
•Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure.
Refer to Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction
section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Faulty operation of transmission fluid pressure switch. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Checks
Action
Checks Action
Definition:
Shift down or engine overrun occurs above than kick-down area.
Diagnosis Hints The same causes as in category No. “C1 - C8: Engine Race Up (Slipping)” are
suspected.

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ISUZU KB P190 2007

7A2-112 TRANSMISSION CONTROL SYSTEM (JR405E)
D3: Gearshift Point is Low or High at All Points
D4: Gearshift Point is Low or High at Limited Area
D5: No Kick-down
E1: No Gearshift
Checks Action
Definition: • Gearshift point is deviated from the shift speed chart.
• Gear is not shifted up properly, even though the vehicle is accelerating.
• Gear is not shifted immediately and enough acceleration cannot be obtained, even though the accelerator pedal is being stepped on.
Diagnosis Hints • Inspect the output shaft speed (OSS) sensor for faulty operation.
• Incorrect accelerator pedal position signal is suspected. Observe the Accelerator Pedal Position (APP). APP parameter should change linearly
from 0 to 99 or 100% according to the accelerator pedal operation.
Checks Action
Definition:
The engine speeds up but the vehicle speed does not increase when the accelerator pedal is being stepped on at starting.
Diagnosis Hints Incorrect accelerator pedal position signal is suspected. Observe the
Accelerator Pedal Position (APP). APP parameter should change linearly from
0 to 99 or 100% according to the accelerator pedal operation.
Checks Action
Definition: • Gear is fixed, such as no gearshift from 1st to 2nd, 2nd to 3rd, and 3rd to 4th.
• Sometimes the gear is shifted, and sometimes it is not possible.
Diagnosis Hints • Fixing at same gear speed, a signal error from the accelerator pedal
position (APP) sensor or trouble in the transmission main unit are
suspected.
• Slipping of the clutch is suspected. Gear ratio error DTC might be set.
Transmission Range Switch & Selector Lever
Cable Checks Inspect the transmission range switch and selector lever cable for misadjusting
or disordering. Refer to On-Vehicle Service section.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission
fluid is extremely blacked, contaminated or smells burnt, slipping of clutch is
suspected.
• Low quantity
• Contamination
•Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure.
Refer to Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction
section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect the low clutch, high clutch or low & reverse brake for slipping.

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-113
E2: Only 4th Gear is Not Selectable
E3: Gear is Changed from 2nd to 3rd in 2 Range
E4: Gear is Changed from 1st to 2nd in L Range
E5: Gear is Changed from 3rd to 4th in 3 Range
Sensor Checks Inspect the input shaft speed (ISS) sensor and output shaft speed (OSS)
sensor for faulty operation.
Additional Checks • Inspect the TCM grounds for being clean, tight, and in their proper
locations.
• Observe the Accelerator Pedal Position (APP). APP parameter should change linearly from 0 to 99 or 100% according to the accelerator pedal
operation.
Checks
Action
Checks Action
Definition:
Gearshift is not possible from 3rd to 4th even though the vehicle is accelerating.
Diagnosis Hints When the transmission fluid temperature is lower than 10 °C (50 °F), gearshift
from the 3rd to the 4th is inhibited.
Transmission Range Switch & Selector Lever
Cable Checks Inspect the transmission range switch and selector lever cable for misadjusting
or disordering. Refer to On-Vehicle Service section.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission
fluid is extremely blacked, contaminated or smells burnt, slipping of clutch is
suspected.
• Low quantity
• Contamination
•Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure.
Refer to Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction
section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect the low clutch for seizing.
Sensor Checks Inspect the transmission fluid temperature (TFT) sensor. Use the Temperature
vs. Resistance table to test the TFT sensor at various temperature levels to
evaluate the possibility of a skewed sensor.
Checks Action
Definition: • Gear is shifted from 2nd to 3rd in 2 range.
• Gear is shifted from 1st to 2nd in L range.
• Gear is shifted from 3rd to 4th in 3 range.
Transmission Range Switch & Selector Lever
Cable Checks Inspect the transmission range switch and selector lever cable for misadjusting
or disordering. Refer to On-Vehicle Service section.

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ISUZU KB P190 2007

7A2-114 TRANSMISSION CONTROL SYSTEM (JR405E)
F1: Low Maximum Speed or Poor Acceleration
F2: Engine Race Up (Slipping) During Acceleration
Control Valve Body ChecksInspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Checks
Action
ChecksAction
Definition: • Starting acceleration is poor.
• Acceleration is slow, even though the accelerator pedal is stepped on during the running.
Diagnosis Hints In addition to the low engine output, faulty gearshift of the transmission or
fixing at the 3rd gear in the fail-safe operation may also be possible.
Therefore, if “maximum speed is low, and acceleration is poor”, it should be
cleared up whether the trouble originates from the engine system or
transmission control system by a running test, inspection of stall speed, etc.
Transmission Range Switch & Selector Lever
Cable Checks Inspect the transmission range switch and selector lever cable for
misadjusting or disordering. Refer to On-Vehicle Service section.
Transmission Fluid Checks Inspect the transmission fluid for the following conditions. If the transmission
fluid is extremely blacked, contaminated or smells burnt, slipping of clutch is
suspected.
• Low quantity
• Contamination
• Smell
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure.
Refer to Line Pressure Test in Test Instruction section.
Stall Speed Checks Inspect the stall speed in forward ranges. Refer to Stall Test in Test Instruction
section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On-Vehicle Service section.
• Clogged hydraulic circuit
Torque Converter Checks Inspect the torque converter for faulty operation.
Clutch and Brake Checks Inspect the low clutch and high clutch for slipping.
Additional Checks • Inspect the engine for proper outputs. Refer to appropriate inspection
chart in engine section.
• Inspect the TCM grounds for being clean, tight, and in their proper locations.
• Observe the Accelerator Pedal Position (APP). APP parameter should change linearly from 0 to 99 or 100% according to the accelerator pedal
operation.
Checks Action
Definition: • Engine speed increases but the vehicle speed does not increase when the accelerator pedal is being stepped on.

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ISUZU KB P190 2007

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-115
F3: Noise or Vibration Occurs During in R, D, 3, 2 or L Range
F4: Engine Brake Does Not Apply in L Range
F5: Engine Stalls Before Vehicle Stops from Running
G1: Vehicle Moves in P Range or Parking is Not Disengaged in Other Than P Range
Diagnosis Hints The same causes as in category No. “C1 - C8: Engine Race Up (Slipping)”
are suspected. When the condition of No. C1 - C8 grows worse, No. F2
results.
Checks Action
Definition:
Noise or vibration occurs in the vicinity of the transmission during running.
Diagnosis Hints Cause other than transmission is suspected. Reproduce the running
condition using a lift up, chassis dynamo, etc. to investigate the origin of the
noise and vibration.
Additional Checks • Inspect the differential gear noise.
• Inspect the propeller shaft noise.
• Inspect the tires for unbalanced or poor uniformity.
Checks
Action
Checks Action
Definition:
The engine brake does not apply, allowing the vehicle to run freely when the accelerator pedal is released at low speed in L
range.
Diagnosis Hints • Slipping of the clutch is suspected. Gear ratio error DTC might be set.
Line Pressure Checks Inspect the line pressure in forward ranges for a possible dropped pressure.
Refer to Line Pressure Test in Test Instruction section.
Control Valve Body Checks Inspect the valve body for the following conditions.
• Faulty operation
• Sticking spool valve
• Sticking shift solenoid valve. Perform function check. Refer to On- Vehicle Service section.
• Clogged hydraulic circuit
Clutch and Brake Checks Inspect the low & reverse brake for slipping.
Sensor Checks Inspect the input shaft speed (ISS) sensor and output shaft speed (OSS)
sensor for faulty operation.
Checks Action
Definition:
The engine stalls simultaneously with the vehicle when the brake pedal is stepped on to stop the vehicle during running.
Diagnosis Hints The same causes as in category No. “B5: Engine Stalls When Selector Lever
is Changed from N to R, D, 3, 2 or L Range” is suspected.
Checks Action
Definition:
Vehicle moves even though it stops on a slope and P range is selected.
Vehicle does not move even though a position other than P range is selected, and the accelerator pedal is being stepped on.
Diagnosis Hints If the vehicle moves in N range, refer to category No. “B1: Vehicle Runs in
N Range”.

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