And the tac turns on and off randomly more off than on
The IAT (Intake Air Temperature) sensor is a thermistor that varies resistance based upon the temperature of the engine intake air. Usually a two wire sensor. One wire is supplied 5 Volt from the PCM (Powertrain Control Module) and the other is a ground. The PCM monitors the change in the 5 Volt supplied to determine air temperature. When the intake air is cold, the resistance is high, resulting in a high signal voltage.
When the intake air is warm, the reistance is low, resulting in a low signal voltage. This code means that the PCM saw a larger-than-normal change in a shorter-than-expected time on the IAT signal circuit.
Since this code is likely pointing to an intermittent problem on the IAT circuit, there may not be any symptoms at present. However, the MIL will likely be on. The car MAY exhibit some drivability problems, but it is more likely that there will be no noticeable symptoms to the driver.
Potential causes of the P0111 DTC include:
a bad IAT sensor
an open in the signal or ground circuit
a short to ground on the signal circuit
poor connection at sensor or PCM
Possible Solutions:
If there are other IAT codes present, diagnose them first. If not, then, using a scan tool verify the IAT voltage with KOEO (Key on engine off).
If, on a cold engine it reads the same as the CTS (Coolant temperature sensor), then the problem is intermittent. But if the IAT reading isn't the same as the CTS refer to diagnostic procedure for P0110. If your scan tool has a freeze frame failure records feature, use it to see what the IAT reading was at the time of the failure. If the reading was at negative 30 or so degrees F (indicating it was at the extreme coldest reading), then there was an intermittent high resistance reading on the IAT signal circuit.
Check for an open ground on the ground circuit and signal circuit. If they are OK, try raising and lowering the temperature of the IAT sensor artificially. Do this by removing the IAT and putting it in a freezer and then applying heat with a heat gun (be careful not to apply too much heat to the IAT with the heat gun or it'll melt the sensor). Watch the resistance change using an ohmmeter attached to each terminal. It should vary smoothly with no sudden jumps. If the reading jumps suddenly, then repace the IAT sensor.
However if the freeze frame reading was at the highest extreme (above 250 deg. F) then there was an intermittent low resistance on the signal circuit. Check for a short to ground on the signal circuit. If it appears OK, then do the above artificial heat test and replace the IAT as necessary. If the problem can't be duplicated, use a voltmeter to watch the signal voltage as you "wiggle" test the wiring harness. Watch for a sudden change in voltage indicating a short or open. Replace IAT as necessary.
This is a pretty simple code and it only really looks for extremely short changes that are relatively high in voltage. It's usually the sensor that is bad unless the vehicle is extremely old, in which case there may be harness problems.
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SOURCE: 1993 Mustang Convertible Airbag Code 24. What's wrong?
Safing Sensor Diagnostic Circuit Open Or Low Resistance In A Primary Crash Sensor.
Each primary crash sensor has an internal resistor. The diagnostic monitor uses the resistor in the primary crash sensors in combination with the two resistors inside the diagnostic monitor to create a tightly controlled diagnostic voltage at Pin 11 (Circuit 614, GY/O). The primary crash sensors are tied together inside the diagnostic monitor at Pins 17 (Circuit 617, PK/O), 18 (Circuit 619, PK/W) and 19 (Circuit 621, W/Y). Therefore, the resistors in the sensors are connected in parallel. The parallel combination of all three sensor resistors should be equal to 393 ohms. The resistance of each sensor should be 1180 (± 20 ohms) ohms.
The resistors inside the diagnostic monitor are connected to Pins 11 (Circuit 614, GY/O) and 12 (Circuit 623, P/W) and are equal in value. Note that Circuits 614 and 623 are tied together inside the safing sensor. Therefore, the two resistors inside the diagnostic monitor are connected in parallel and will function the same as one resistor of half the original value. Current flows from Pins 1 and 6 through the resistors, out to Circuits 614 (GY/O) and 623 (P/W) on Pins 11 and 12, through the LH B-pillar safing sensor and out to the driver side air bag. Current flows through the driver side air bag and into Pin 10 (Circuit 615, GY/W). Current then flows from Pin 10 through the diode inside the diagnostic monitor and out to the primary crash sensors through Pins 17, 18 and 19. The current flows through each primary crash sensor resistor and ends at the case ground of each sensor. Pin 11 is the midpoint of the resistor network and voltage at Pin 11 will change with vehicle charging system voltage. The expected voltage at Pin 11 is shown in the table below. The diagnostic monitor measures the vehicle charging system voltage at Pin 13 (battery input). By measuring the voltage at Pin 13, the diagnostic monitor can accurately predict what the voltage at Pin 11 should be in a normal functioning system.
If the connection between Circuits 614 (GY/O) and 623 (P/W) inside the safing sensor is broken, then the resistor on Pin 12 is no longer in the diagnostic circuit. Both resistors are needed to pull up the diagnostic voltage to the correct value. In this situation, the resistor on Pin 11 is the only resistor inside the diagnostic monitor pulling up the voltage. Therefore, the voltage on Pin 11 will be half of the normal expected voltage and the voltage on Pin 12 will be about equal to the vehicle charging system voltage. The diagnostic monitor does not measure the voltage on Pin 12, so the monitor bases its decision strictly on the voltage at Pin 11. If the voltage at Pin 11 is lower than it should be, the monitor will flash Diagnostic Trouble Code 24. Another situation that can cause low voltage at Pin 11 is a drop in primary crash sensor resistance (resistance is too low). If this occurs, the voltage at Pin 11 will be pulled down to a lower than normal value because the parallel combination resistance of the primary crash sensors will be less than 393 ohms. In this situation, the voltage at Pins 11 and 12 will be identical, but the monitor does not measure the voltage at Pin 12. Therefore, a primary crash sensor with low resistance may cause low voltage at Pin 11 and the monitor will flash Diagnostic Trouble Code 24 on the air bag indicator.
Here is a wiring schematic of this.
http://i253.photobucket.com/albums/hh43/chuck943/93mustangairbag.gif
Throttle/Pedal Position Sensor A Circuit Low
Possible Causes:
Open ETC TP sensor harness.Short to ground in the ETC TP sensor harness.Damaged TP sensor.SIG RTN circuit open to the TP sensorPCM has failed
Trouble Code: P0123
Throttle/Pedal Position Sensor A Circuit High
Possible Causes:
TP sensor not seated correctly.TP sensor harness is short to voltage.TP sensor harness short to VREF.SIG RTN circuit open to the TP sensor.Damaged TP sensor.PCM has failed.Trouble Code: P2104
Throttle Actuator Control (TAC) System (Forced Idle)
Possible Causes:
Air cleaner and air inlet are not correctly seated.Check for self-test DTCs in all of the vehicle modules.Accelerator Pedal Position (APP) sensor.Throttle Position (TP) sensor.Manifold Absolute Pressure (MAP) sensor.PCM has failed.
Mustang 2006-2008
4.0L V6 VIN N Auto 12
Trouble Code: P2008
Intake Manifold Runner Control (IMRC) Circuit Open (Bank 1)
Possible Causes:
IMRC monitor circuit open
Trouble Code: P2014
Intake Manifold Runner Position Sensor/Switch Circuit (Bank 1)
Possible Causes:
IMRC monitor circuit openMechanical concern - bind, seize, damage or obstruction of IMRC hardware
Trouble Code: P2015
Intake Manifold Runner Position Sensor/Switch Circuit Range/Performance (Bank 1)
Possible Causes:
Mechanical concern - bind, seize, damage, or obstruction of IMRC hardware
Trouble Code: P2019
Intake Manifold Runner Position Sensor/Switch Circuit (Bank 2)
Possible Causes:
IMRC monitor circuit openMechanical concern - bind, seize, damage, or obstruction of IMRC hardware
Trouble Code: P2020
Intake Manifold Runner Position Sensor/Switch Circuit Range/Performance (Bank 2)
Possible Causes:
Mechanical concern - bind, seize, damage, or obstruction of IMRC hardware
Trouble Code: P2065
Fuel Level Sensor B Circuit
Possible Causes:
Communication link concernDamaged Instrument Panel Cluster (IPC) (MKS)Damaged Instrument Cluster (IC)Damaged PCM
Trouble Code: P2066
Fuel Level Sensor B Circuit Range/Performance
Possible Causes:
Communication link concernDamaged Instrument Panel Cluster (IPC) (MKS)Damaged Instrument Cluster (IC)Damaged PCM
Trouble Code: P2067
Fuel Level Sensor B Circuit Low
Possible Causes:
Communication link concernDamaged Instrument Panel Cluster (IPC) (MKS)Damaged Instrument Cluster (IC)Damaged PCM
Trouble Code: P2068
Fuel Level Sensor B Circuit High
Possible Causes:
Communication link concernDamaged Instrument Panel Cluster (IPC) (MKS)Damaged Instrument Cluster (IC)Damaged PCM
Trouble Code: P2070
Intake Manifold Tuning Valve (IMTV) Stuck Open (Bank 1)
Possible Causes:
IMTV signal circuit shorted to PWR GND or SIG RTNDamaged IMRC actuatorPCM has failed
Trouble Code: P2071
Intake Manifold Tuning Valve (IMTV) Stuck Closed Bank 1
Possible Causes:
IMTV signal circuit shorted to PWR GND or SIG RTNDamaged IMRC actuatorIMTV circuit openPCM has failed
Trouble Code: P2072
Throttle Actuator Control (TAC) System (Ice Breakage)
Possible Causes:
Ice or oil in the intake air system could be the result of a Positive Crankcase Ventilation (PCV) system concern
Trouble Code: P2096
Post Catalyst Fuel Trim System Too Lean (Bank 1)
Possible Causes:
Loose connection, and damaged or corroded terminalsExhaust leaksContaminated HO2S
Trouble Code: P2097
Post Catalyst Fuel Trim System Too Rich (Bank 1)
Possible Causes:
Loose connection, and damaged or corroded terminalsExhaust leaksContaminated HO2S
Trouble Code: P2098
Post Catalyst Fuel Trim System Too Lean (Bank 2)
Possible Causes:
Loose connection, and damaged or corroded terminalsExhaust leaksContaminated HO2S
Trouble Code: P2099
Post Catalyst Fuel Trim System Too Rich (Bank 2)
Possible Causes:
Loose connection, and damaged or corroded terminalsExhaust leaksContaminated HO2S
Trouble Code: P2100
Throttle Actuator Control (TAC) Motor Circuit/Open
Possible Causes:
TAC motor has an open windingTAC motor is damagedTAC motor harness is openTAC motor harness is short to PWRTAC motor harness circuits are short togetherTAC motor harness connector is unplugged
Trouble Code: P2101
Throttle Actuator Control (TAC) Motor Range/Performance
Possible Causes:
TAC motor circuits are cross-wired
Trouble Code: P2104
Throttle Actuator Control (TAC) System (Forced Idle)
Possible Causes:
Air cleaner and air inlet are not correctly seatedCheck for self-test DTCs in all of the vehicle modules.Accelerator Pedal Position (APP) sensorThrottle Position (TP) sensorManifold Absolute Pressure (MAP) sensorPCM has failed
Trouble Code: P2105
Throttle Actuator Control (TAC) System (Forced Engine Shutdown)
Possible Causes:
Air cleaner and air inlet are not correctly seated.Check for self-test DTCs in all of the vehicle modules.Accelerator Pedal Position (APP) sensor.Throttle Position (TP) sensor.Manifold Absolute Pressure (MAP) sensor.PCM has failed.
Trouble Code: P2107
Throttle Actuator Control (TAC) Module Processor
Possible Causes:
TAC motor harness circuit short to ground.TAC motor harness circuit short to voltage.Damaged Electronic Throttle Body (ETB).PCM has failed.
Trouble Code: P2110
Throttle Actuator Control (TAC) System (Forced Limited RPM)
Possible Causes:
Air cleaner and air inlet are not correctly seated.Check for self-test DTCs in all of the vehicle modules.Accelerator Pedal Position (APP) sensor.Throttle Position (TP) sensor.Manifold Absolute Pressure (MAP) sensor.PCM has failed.
Trouble Code: P2111
Throttle Actuator Control (TAC) System (Stuck Open)
Possible Causes:
Binding throttle body, stuck open.TAC motor circuit open.TAC motor circuits are cross-wired.TAC motor harness circuits are shorted together.PCM has failed.
Trouble Code: P2112
Throttle Actuator Control (TAC) System - Stuck Closed
Possible Causes:
Binding throttle body, stuck open.TAC motor circuit open.TAC motor circuits are cross-wired.TAC motor harness circuits are shorted together.PCM has failed.
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