4L60E transmission
Thread Starter
6th Gear
Joined: Feb 2010
Posts: 6
Likes: 0
From: Orlando Florida
4L60E transmission
Ok guys I'm new to the Corvette world and have some questions so forgive my ignorance. I just bought a 98 vette with a 575 hp SLP package that has a 4L60E automatic transmission from Art Carr. When I start to move it is fine and shifts from 1st to 2nd but if I try to speed up even a little (like 1/32nd throttle) it will throw it back into 1st and I will cruise down the road at 30mph at 2500 rpm. Besides getting about 5 mpg I don't think this is normal (it didn't do this for my first 200 miles of driving). Could I have accidently tripped the overdrive or do I have more serious problems? Thanks
Pro
Joined: Feb 2009
Posts: 651
Likes: 33
From: North Port Florida
You're going to have to buy a set of repair manuals from Chevrolet. All the pinpoint tests are in there. It sounds like it could be a throttle position sensor which are on the accelerator pedal , if it's fly by wire. Good luck!!!
Melting Slicks
Joined: Oct 2007
Posts: 2,383
Likes: 13
From: Kinston North Carolina
A little reading:
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DTC P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance
Circuit Description
The commanded throttle position, based on accelerator pedal position and possibly other limiting factors, is compared to the Actual throttle position. The 2 values should be within a calibrated range of each other. Both the PCM and the TAC module redundantly monitor the Commanded and Actual throttle position. This DTC sets if the TAC module detects the problem.
Conditions for Running the DTC
DTC P1518 is not set.
The ignition switch is in the crank or run position.
The ignition voltage is greater than 5.23 volts.
Not in battery saver mode.
Conditions for Setting the DTC
The TAC module detects that the commanded and actual throttle positions are not within a calibrated range of each other or the PCM and the TAC cannot determine throttle position or both TP sensors are invalid.
All above conditions met for less than 1 second.
Action Taken When the DTC Sets
The PCM will illuminate the Malfunction Indicator Light (MIL) when this diagnostic runs and fails.
The Reduced Engine Power message displays on the drivers information center.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
If no other TAC System DTCs are set, the TAC System will operate in Reduced Engine Power mode. If certain TAC System DTCs are set at the same time, the TAC System either defaults to a more tightly restricted mode of operation if the TAC determines that limited safe operation is possible, or the TAC commands the engine to shut down.
Conditions for Clearing the MIL/DTC
The PCM turns the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
The PCM battery voltage is interrupted.
Important
The clear DTC info function may have to be performed twice in order to clear a Throttle Actuator Control System DTC.
Clear the MIL/DTC information using a scan tool.
Diagnostic Aids
Important
Ensure that the starting and charging systems are operating properly. Low system voltage causes this DTC to set.
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
The following may cause an intermittent:
Poor connections. Check for adequate terminal tension. Refer to Troubleshooting Procedures, Checking Terminal Contact (Body and Accessories/Wiring Systems) for proper procedure.
Corrosion
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs should be set and no circuit or component problems can be located.
For an intermittent condition refer to Symptoms .
If a repair is completed and the DTC was cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred.
When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
If the TP Indicated Angle does not follow the movement of the throttle blade, and no TP Sensor DTCs are set, there is a mechanical problem with the throttle shaft or the TP Sensor. Re-install the air inlet duct after you complete the repairs.
When a problem is detected within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. It is possible that locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
-------------------------------------------------
DTC P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance
Circuit Description
The commanded throttle position, based on accelerator pedal position and possibly other limiting factors, is compared to the Actual throttle position. The 2 values should be within a calibrated range of each other. Both the PCM and the TAC module redundantly monitor the Commanded and Actual throttle position. This DTC sets if the TAC module detects the problem.
Conditions for Running the DTC
DTC P1518 is not set.
The ignition switch is in the crank or run position.
The ignition voltage is greater than 5.23 volts.
Not in battery saver mode.
Conditions for Setting the DTC
The TAC module detects that the commanded and actual throttle positions are not within a calibrated range of each other or the PCM and the TAC cannot determine throttle position or both TP sensors are invalid.
All above conditions met for less than 1 second.
Action Taken When the DTC Sets
The PCM will illuminate the Malfunction Indicator Light (MIL) when this diagnostic runs and fails.
The Reduced Engine Power message displays on the drivers information center.
The PCM records the operating conditions at the time the diagnostic fails. The PCM stores this information in the Freeze Frame and/or Failure Records.
If no other TAC System DTCs are set, the TAC System will operate in Reduced Engine Power mode. If certain TAC System DTCs are set at the same time, the TAC System either defaults to a more tightly restricted mode of operation if the TAC determines that limited safe operation is possible, or the TAC commands the engine to shut down.
Conditions for Clearing the MIL/DTC
The PCM turns the MIL OFF after three consecutive drive trips that the diagnostic runs and does not fail.
A last test failed (Current DTC) will clear when the diagnostic runs and does not fail.
A History DTC clears after forty consecutive warm-up cycles, if this or any other emission related diagnostic does not report any failures.
The PCM battery voltage is interrupted.
Important
The clear DTC info function may have to be performed twice in order to clear a Throttle Actuator Control System DTC.
Clear the MIL/DTC information using a scan tool.
Diagnostic Aids
Important
Ensure that the starting and charging systems are operating properly. Low system voltage causes this DTC to set.
Important
Remove any debris from the PCM\TAC module connector surfaces before servicing the PCM\TAC module. Inspect the PCM\TAC module connector gaskets when diagnosing/replacing the modules. Ensure that the gaskets are installed correctly. The gaskets prevent contaminate intrusion into the PCM\TAC modules.
The following may cause an intermittent:
Poor connections. Check for adequate terminal tension. Refer to Troubleshooting Procedures, Checking Terminal Contact (Body and Accessories/Wiring Systems) for proper procedure.
Corrosion
Mis-routed harness
Rubbed through wire insulation
Broken wire inside the insulation
Inspect the TAC module connectors for signs of water intrusion. When this occurs, multiple DTCs should be set and no circuit or component problems can be located.
For an intermittent condition refer to Symptoms .
If a repair is completed and the DTC was cleared using a scan tool on the same ignition cycle, the default action will not clear until an ignition cycle has occurred.
When the TAC module detects a problem within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. Locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
Test Description
The numbers below refer to the step numbers on the diagnostic table.
If the TP Indicated Angle does not follow the movement of the throttle blade, and no TP Sensor DTCs are set, there is a mechanical problem with the throttle shaft or the TP Sensor. Re-install the air inlet duct after you complete the repairs.
When a problem is detected within the TAC System, more than one TAC System related DTC may set. This is due to the many redundant tests run continuously on this system. It is possible that locating and repairing one individual problem may correct more than one DTC. Keep this in mind when reviewing captured DTC info.
