DTC P1516 Throttle Actuator Control (TAC) Module Throttle Actuator Position Performance

TechInfo · Joined: 26 Oct 2004 Posts: 2989

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 - Requested/Actual Throttle Position Performance (TAC)

Step	Action	Value(s)	Yes	No
1	Did you perform the Powertrain On-Board Diagnostic (OBD) System Check?	--	Go to Step 2	Go to Powertrain On Board Diagnostic (OBD) System Check
2	Is DTC P1518 and P1221 also set?	--	Go to DTC P1518	Go to Step 3
3	Is DTC P1221 set?	--	Go to DTC P1221	Go to Step 4
4	Turn OFF the ignition for 15 seconds. Turn ON the ignition leaving the engine OFF. Monitor the TP sensor 1 and 2 angle in the TAC data list using the scan tool. Slowly depress the accelerator pedal to Wide Open Throttle (WOT) and then slowly return it to closed throttle. Does the TP sensor 1 and 2 Angle increase as the pedal is depressed and then decrease as the pedal is released?	--	Go to Diagnostic Aids	Go to Step 5
5	Turn OFF the ignition. Remove the duct from the Throttle Body Assembly. Important Disconnecting the Throttle Actuator Control motor connector will cause additional DTCs to set. Disconnect the Throttle Actuator Control motor harness connector. Turn ON the ignition leaving the engine OFF. Open the throttle blade to Wide Open Throttle (WOT) by hand and then close the throttle blade while observing the TP sensor 1 and 2 Angle on the scan tool. Does the TP sensor 1 and 2 Angle increase as the throttle blade is opened and decrease as the throttle is closed?	--	Go to Step 6	Go to Step 17
6	Turn OFF the ignition. Leave the Throttle Actuator Control motor disconnected. Disconnect the TAC module 16-way connector containing the Throttle Actuator control motor circuits. Refer to PCM/TAC Module Replacement . Turn ON the ignition leaving the engine OFF. Measure the voltage from each of the Throttle Actuator Control motor harness connector to the battery ground. Check both Throttle Actuator Control motor circuits using the DMM . Is any voltage present?	--	Go to Step 11	Go to Step 7
7	Check the continuity of each of the Throttle Actuator Control motor circuit between the Throttle Actuator Control motor and the TAC module 16-way connector using the DMM . Does the DMM indicated continuity on both circuits?	--	Go to Step 8	Go to Step 12
8	Check the continuity of each Throttle Actuator Control motor circuit to battery ground using the DMM . Does the DMM indicate continuity?	--	Go to Step 13	Go to Step 9
9	Check the continuity of each Throttle Actuator Control motor circuit at the TAC module harness connector and all other circuits in both TAC module connectors using the DMM . Does the DMM indicate continuity?	--	Go to Step 14	Go to Step 10
10	Turn OFF the ignition. Connect a test lamp between the two terminals of the Throttle Actuator Control motor harness connector. Observe the test lamp as the ignition switch is turned ON. Does the test lamp illuminate briefly when the ignition is turned ON?	--	Go to Step 16	Go to Step 18
11	Repair the short to voltage on the affected Throttle Actuator Control motor circuit. Refer to Body and Accessories/Wiring Systems. Is the action complete?	--	Go to Step 19	--
12	Repair the open/high resistance on the affected Throttle Actuator Control motor circuit. Refer to Body and Accessories/Wiring Systems. Is the action complete?	--	Go to Step 19	--
13	Repair the short to ground on the affected Throttle Actuator Control motor circuit. Refer to Body and Accessories/Wiring Systems. Is the action complete?	--	Go to Step 19	--
14	Repair the circuits that are shorted together. Refer to Body and Accessories/Wiring Systems. Is the action complete?	--	Go to Step 19	--
15	Check for poor connection/terminal tension at the Throttle Actuator Control motor harness connector. Refer to Body and Accessories/Wiring Systems for the proper procedure. Did you find and correct the condition?	--	Go to Step 19	Go to Step 16
16	Replace the throttle body assembly. Is the action complete?	--	Go to Step 19	--
17	Check for poor connections/terminal tension at the TAC Module harness connectors. Refer to Body and Accessories/Wiring Systems for proper procedure. Did you find and correct the condition?	--	Go to Step 19	Go to Step 18
18	Replace the TAC module. Refer to PCM/TAC Module Replacement . Is the action complete?	--	Go to Step 19	--
19	Select the Diagnostic Trouble Code (DTC) option and the Clear DTC Information option using the scan tool. Idle the engine at the normal operating temperature. Select the Diagnostic Trouble Code (DTC) option and the Specific DTC option, then enter the DTC number using the scan tool. Operate the vehicle within the Conditions for Running the DTC as specified in the supporting text, if applicable. Does the scan tool indicate that this diagnostic ran and passed?	--	Go to Step 20	Go to Step 2
20	Select the Capture Info option and the Review Info option using the scan tool. Does the scan tool display any DTCs that you have not diagnosed?	--	Go to the applicable DTC table	System OK