What does this code REALLY mean
Thread Starter
Team Owner
Joined: Dec 2000
Posts: 27,897
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From: I have no tolerence for liberals and fools, but sometimes i repeat myself
CI 3-5-7-8-9 Veteran
St. Jude Donor '08
What does this code REALLY mean
P1518
PCM to TAC serial data circuit
What does this really mean?
PCM to TAC serial data circuit
What does this really mean?
Team Owner
Joined: Sep 2001
Posts: 23,283
Likes: 906
From: Lake Elsinore, CA
Here's part of the diagnostic from the manual for you to chew on first.
DTC P1518 Throttle Actuator Control (TAC) Module Serial Data Circuit
Circuit Description
The TAC Module and the PCM communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity but also adequate system voltage. This diagnostic monitors the accuracy of the serial data transmitted between the TAC Module and the PCM. If the PCM detects a loss of data or invalid data, this DTC sets.
Conditions for Running the DTC
The ignition switch is in the crank or run position.
The ignition voltage is greater than 5.23 volts.
Conditions for Setting the DTC
Invalid or missing serial data messages are detected for a predetermined amount of time.
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.
If DTC P0606 is set with DTC P1518, the TAC commands an engine 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
DTC P1518 sets if the battery voltage is low. If the customers concern is slow cranking or no crank because battery voltage is low, ignore DTC P1518. Clear any DTCs from memory that may have set from the low battery voltage condition.
DTC P1518 sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness (i.e. cruise, brake). An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.
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.
DTC P1518 Throttle Actuator Control (TAC) Module Serial Data Circuit
Circuit Description
The TAC Module and the PCM communicate via a dedicated serial data circuit. This serial data circuit is separate from any other serial data circuit on the vehicle. Accurate transmitting and receiving of serial data requires not only good circuit integrity but also adequate system voltage. This diagnostic monitors the accuracy of the serial data transmitted between the TAC Module and the PCM. If the PCM detects a loss of data or invalid data, this DTC sets.
Conditions for Running the DTC
The ignition switch is in the crank or run position.
The ignition voltage is greater than 5.23 volts.
Conditions for Setting the DTC
Invalid or missing serial data messages are detected for a predetermined amount of time.
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.
If DTC P0606 is set with DTC P1518, the TAC commands an engine 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
DTC P1518 sets if the battery voltage is low. If the customers concern is slow cranking or no crank because battery voltage is low, ignore DTC P1518. Clear any DTCs from memory that may have set from the low battery voltage condition.
DTC P1518 sets when there is a short to B+ on the TAC module ground circuit. Inspect the fuses for the circuits that are in the TAC module harness (i.e. cruise, brake). An inspection of the fuses may lead you to the circuit that is shorted to the TAC module ground circuit.
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.
Thread Starter
Team Owner
Joined: Dec 2000
Posts: 27,897
Likes: 9
From: I have no tolerence for liberals and fools, but sometimes i repeat myself
CI 3-5-7-8-9 Veteran
St. Jude Donor '08
ok here's what happened. I was coasting up to a red light when the dic says "reduced engine power". I did not realize the reduced meant idle. I Idled the car off the side of the road, turned the car off, pulled the key and them restarted. drove home as normal except the check engine light was on
Thread Starter
Team Owner
Joined: Dec 2000
Posts: 27,897
Likes: 9
From: I have no tolerence for liberals and fools, but sometimes i repeat myself
CI 3-5-7-8-9 Veteran
St. Jude Donor '08
ok here's what happened. I was coasting up to a red light when the dic says "reduced engine power". I did not realize the reduced meant idle. I Idled the car off the side of the road, turned the car off, pulled the key and them restarted. drove home as normal except the check engine light was on
