Allison

Allison 1000 & 2000 Gen 4 Fault Codes: P0708 Transmission Range Sensor Circuit High Input

CIRCUIT DESCRIPTION:
The installation of a transmission-mounted Neutral Start/Back-Up (NSBU) switch is required. This switch mounts directly onto the transmission housing from the outside and detects the angular position of the shift selector shaft. This position is communicated to the Transmission Control Module (TCM) so that certain vehicle control functions can be coordinated with the position of the shift controls. The NSBU switch has redundant circuitry to alert the TCM in the event of a single wire or switch failure.

The neutral signal output of the NSBU switch is typically used as confirmation that the transmission is in N (Neutral) before the engine starter is engaged. The NSBU switch is interfaced to the starter circuit with weatherproof electrical connectors. The reverse signal provision may be used to activate vehicle back-up lights and/or reverse warning devices.

CONDITIONS FOR RUNNING THE DTC:
1. The components are powered and ignition voltage is greater than 9V and less than 18V.
2. Engine speed is greater than 200 rpm and less than 7500 rpm for 5 seconds.

CONDITIONS FOR SETTING THE DTC – SOFTWARE LEVELS PRIOR TO N11:
DTC P0708 sets when the TCM detects an invalid condition or parity errors occurring over consecutive ignition cycles.

ACTION TAKEN WHEN THE DTC SETS – SOFTWARE LEVELS PRIOR TO N11:
1. The diagnostic response is to shut all solenoids off and allow the transmission to operate in hydraulic default mode or “limp home”. Shift selector and hydraulic state of logic valves determines range attained.
2. DTC P0708 is stored in the TCM history.
3. The CHECK TRANS light illuminates.
4. The TCM inhibits TCC engagement.
5. Due to this failure and associated responses, P0722 and P0845 may also set.

ACTION TAKEN WHEN THE DTC SETS – SOFTWARE LEVEL N11 AND LATER:
1. The CHECK TRANS light illuminates but no diagnostic response is implemented until after 50 warm-up cycles occur when a NSBU switch parity error is active. A warm-up cycle is defined as a 20 degree change in transmission temperature.
2. The diagnostic response is to shut all solenoids off and allow the transmission to operate in hydraulic default mode or “limp home.” Shift selector and hydraulic state of logic valves determines range attained.
3. DTC P0708 is stored in the TCM history.
4. The TCM inhibits TCC engagement.
5. Due to this failure and associated responses, P0722 and P0845 may also set.
6. A shift to R (Reverse) will allow reverse range if a P0876 (previously P1714) is not active.

CONDITIONS FOR CLEARING THE MIL/DTC
A Scan Tool may be used to clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without failure.

DIAGNOSTIC AIDS:
Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change. You may have to drive the vehicle in order to experience a fault.

When a P0708 is shown in failure records, this indicates that conditions to set a P0708 were present at one time. If the condition was due to moisture intrusion, the moisture may no longer be present, and thus you may not be able to reproduce the DTC. In such case, variables such as vehicle mileage, external physical condition of the switch should be factored in when making a decision to replace the NSBU switch.

NOTE: Due to the TCM logic used to detect and set a P0708, this code can remain active even after a NSBU switch replacement is complete and the ignition has been cycled. It is important to clear all active DTCs from the TCM after servicing the NSBU switch.

Allison 1000 & 2000 Gen 4 Fault Codes: P0711 Transmission Fluid Temperature Sensor Circuit Performance

CIRCUIT DESCRIPTION:
The Transmission Fluid Temperature (TFT) sensor is part of the Pressure Switch Manifold (PSM) which is located in the transmission oil pan. The TFT sensor is a thermistor that changes its resistance value based on the temperature of the transmission fluid. The Transmission Control Module (TCM) supplies a 5V reference signal to the TFT sensor and measures the voltage drop in the circuit. When the transmission is cold, the sensor resistance is high and the TCM detects high signal voltage. As the transmission fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The TCM uses this information to control shift quality and to determine torque converter clutch applies.

If the TCM detects the TFT sensor resistance has no change, an unrealistic change in a short amount of time, or multiple changes within seconds, DTC P0711 sets.

CONDITIONS FOR RUNNING THE DTC:
1. No DTC P0721, P0722, P0717, P0716, P0713, or P0712.
2. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V TCM).
3. The engine speed is greater than 200 rpm for more than 5 seconds.
4. The engine speed is greater than 450 rpm for more than 2 seconds with output speed of 100 rpm or above. This would indicate that a range is selected.
5. A valid start-up temperature is detected.

CONDITIONS FOR SETTING THE DTC:
DTC P0711 sets when the TCM detects one of the following conditions:
1. The TCM detects a temperature change that is under a set limit when compared to samples of the minimum and maximum temperature values.
2. The TFT has an unrealistic temperature change of more than 10°C (50°F) for 10 occurrences.
3. The temperature from start up decreases 40°C (104°F) or more within duration of 6 or more seconds.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM does not illuminate the CHECK TRANS light.
2. The TCM stores DTC P0711 in TCM history.
3. The TCM uses calibration default for temperature values.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
1. A Scan Tool may be used to clear the code from the TCM history.
2. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the ignition has been cycled.

DIAGNOSTIC AIDS:
1. The Scan Tool transmission fluid temperature (TFT) should rise steadily during warm-up cycles and then stabilize.
2. DTC P0218 may set after DTC P0711 has set. Follow the diagnostic information for DTC P0711 before proceeding to the diagnostic for DTC P0218.

Allison 1000 & 2000 Gen 4 Fault Codes: P0712 Transmission Fluid Temperature Sensor Circuit Low Input (High Temperature)

CIRCUIT DESCRIPTION:
The Transmission Fluid Temperature (TFT) sensor is part of the Pressure Switch Manifold (PSM) which is located in the transmission oil pan. The TFT sensor is a thermistor that changes its resistance value based on the temperature of the transmission fluid. The Transmission Control Module (TCM) supplies a 5V reference to the thermistor. The TCM’s internal impedance provides resistance at the TCM so that voltage drop can be measured between the TCM and the thermistor. When the transmission is cold, the sensor resistance is high and the TCM detects high signal voltage. As the transmission fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The TCM uses this information to control shift quality and to determine torque converter clutch applies.

If the TCM detects a continuous short to ground in the TFT sensor or signal circuit, DTC P0712 is set.

CONDITIONS FOR RUNNING THE DTC:
1. No TFT sensor DTC P0711 or P0713.
2. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V TCM).
3. The engine is greater than 200 rpm for more than 5 seconds.
4. The engine has been running for 20 seconds with a coolant temperature above 20°C (68°F).

CONDITIONS FOR SETTING THE DTC:
DTC P0712 sets when the TFT sensor indicates a voltage of less than 313mV for 2.5 seconds.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM does not illuminate the CHECK TRANS light.
2. The TCM stores DTC P0712 in TCM history.
3. TCM uses calibration default for temperature values.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
1. A Scan Tool may be used to clear the code from the TCM history.
2. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the ignition has been cycled.

DIAGNOSTIC AIDS:
Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

A short to ground on wire 210 may allow a code P0712 to set. A default value of 160°C (320°F) TFT on the Scan Tool would be a good indication this has occurred.

Allison 1000 & 2000 Gen 4 Fault Codes: P0713 Transmission Fluid Temperature Sensor Circuit High Input (Low Temperature)

CIRCUIT DESCRIPTION:
The Transmission Fluid Temperature (TFT) sensor is part of the Pressure Switch Manifold (PSM) which is located in the transmission oil pan. The TFT sensor is a thermistor that changes its resistance value based on the temperature of the transmission fluid. The Transmission Control Module (TCM) supplies a 5V reference to the thermistor. The TCM’s internal impedance provides resistance at the TCM so that voltage drop can be measured between the TCM and the thermistor. When the transmission is cold, the sensor resistance is high and the TCM detects high signal voltage. As the transmission fluid temperature warms to a normal operating temperature, the resistance becomes less and the signal voltage decreases. The TCM uses this information to control shift quality and to determine torque converter clutch applies.

If the TCM detects a continuous open or short-to-power in the TFT sensor or signal circuit, DTC P0713 sets.

CONDITIONS FOR RUNNING THE DTC:
1. No DTC P0711 or P0712.
2. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V TCM).
3. Engine speed is greater than 200 rpm for more than 5 seconds.
4. The engine has been running for 20 seconds with a coolant temperature above 20°C (68°F).

CONDITIONS FOR SETTING THE DTC:
DTC P0713 sets when the TCM detects a voltage greater than 4.84V for 2.5 seconds.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM does not illuminate the CHECK TRANS light.
2. The TCM stores DTC P0713 in TCM history.
3. TCM uses calibration default for temperature values.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
1. A Scan Tool may be used to clear the code from the TCM history.
2. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.
3. The TCM cancels the DTC default actions when the fault no longer exists and the ignition has been cycled.

DIAGNOSTIC AIDS:
Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

An open or a short to power at wire 210 may allow DTC P0713 to set. A default value of -60°C (-76°F) would be a good indication this has occurred.

Allison 1000 & 2000 Gen 4 Fault Codes: P0717 Turbine Speed Sensor Circuit No Signal

CIRCUIT DESCRIPTION:
The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member. Two signal wires extend from one end of the housing and an exposed end of the pole piece is at the opposite end of the housing. The permanent magnet produces lines of flux around the pole piece. As a ferrous object (such as a gear tooth) approaches and passes through the gap at the end of the pole piece, an AC voltage pulse is induced in the wire coil. The Transmission Control Module (TCM) calculates the frequency of these AC pulses and converts it to a speed value. The AC voltage generated varies from 150 mV at low speed to 15V at high speed. The signal wires from the sensor are formed as twisted pairs to cancel magnetically induced fields. The cable is also shielded to protect from voltage related fields. Noise from other sources is eliminated by using two-wire differential inputs at the TCM.

CONDITIONS FOR RUNNING THE DTC:
Components are powered and the ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V or less than 32V (24V TCM).

DTC P0721, P0722, P0731, P0732, P0733, P0734, P0735, P0736, or P1718 is not active.

When unrealistic large change in turbine speed is detected.
1. Engine is running.
2. Shift is not in process.
3. Range attained is not neutral.
4. Transmission fluid temperature is above -25°C (-13°F).

When unrealistic low turbine speed is detected.
1. Engine is running.
2. Shift is not in process.
3. Range attained is not neutral.
4. Transmission fluid temperature is above -25°C (-13°F).
5. Transmission output speed is at or above 150 rpm or engine speed is at or above 400 rpm.

CONDITIONS FOR SETTING THE DTC:
DTC P0717 is set when one of the following conditions occur:
1. Unrealistic large change in turbine speed. A Failure pending is set if an unrealistic change in transmission turbine speed is detected at or above 800 rpm. The failure pending response is to lock in the current range.
2. Unrealistic low value in turbine speed. A failure pending is set if turbine speed is detected below 61 rpm. A failure is set when turbine speed is below 61 rpm and output speed is detected above 500 rpm for more than 1 second.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0717 is active, the following conditions will occur:
1. If failure occurs while in a forward range and a shift has been completed, the transmission will remain in the current range.
2. If failure occurs while in a forward range and a shift is in progress, the transmission will return to the previous range, except in post-shift state; then the transmission will continue to the commanded range.
3. If failure occurs under other conditions, the transmission shifts to 1st, 3rd, or 5th.
4. If the shift selector is moved to N (Neutral), R (Reverse), or any other forward range, the transmission will lock in N (Neutral).

DTC P0717 is stored in the TCM history.

The CHECK TRANS light illuminates.

The TCM freezes shift adapts (DNA).

The TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
A Scan Tool may be used to clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

You may have to drive the vehicle in order to experience a fault.

If the condition is intermittent, connect the Scan Tool and select the speed sensor indicated by the code. If the signal is erratic, investigate and eliminate the following:
1. Intermittent wiring connection
2. Excessive vibration (driveline or engine torsionals)
3. Irregular sensor gap (loose sensor, loose tone wheel, or damaged tone wheel)

Install a known good speed sensor and see if normal function is restored to rule out an internal short or open in the sensor removed.

Check that the speed sensor wiring consists of twisted pairs at the rate of 12 to 16 twists per 300 mm. These twists must extend the entire length of the wiring harness to within at least 50 mm of the speed sensor connector.

Install a known good TCM, if available. If the DTC does not return, reinstall the old TCM to verify the repair.

Allison 1000 & 2000 Gen 4 Fault Codes: P0719 Brake Switch ABS Input Low

CIRCUIT DESCRIPTION:
If the vehicle is equipped with anti-lock brake system (ABS), an interface between the ABS and TCM is required. This interface allows disengagement of the Torque Converter Clutch (TCC) when the ABS is activated.

This ABS action is initiated with a discrete input from the ABS system, when the ABS is activated a ground signal is sent to TCM input wire 113. This may be a ground signal direct from the ABS controller or a positive signal from the ABS controller that powers a relay field coil to supply a ground through the relay contacts. (Some ABS systems require that the ground signal be switched through a relay.)

CONDITIONS FOR RUNNING THE DTC:
1. Components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V TCM).
2. DTCs P0721, P0722 are not active.

CONDITIONS FOR SETTING THE DTC:
DTC P0719 will set after the TCM detects one or more vehicle acceleration cycles where the TCM ABS brake switch input is in the “ON” activated state.

ACTION TAKEN WHEN THE DTC SETS:
1. The TCM uses the default assumption that the ABS is OFF.
2. DTC P0719 is stored in the TCM history.
3. The CHECK TRANS light illuminates.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
A Scan Tool can be used to clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

When diagnosing for an intermittent short or open, massage the wiring harness while watching the test equipment for a change.

ABS system interface to the TCM input can be wired one of three different ways, check with the OEM for proper wiring information concerning ABS applied input before troubleshooting.

Allison 1000 & 2000 Gen 4 Fault Codes: P0721 Output Speed Sensor Circuit Performance

CIRCUIT DESCRIPTION:
The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member. Two signal wires extend from one end of the housing and an exposed end of the pole piece is at the opposite end of the housing. The permanent magnet produces lines of flux around the pole piece. As a ferrous object (such as a gear tooth) approaches and passes through the gap at the end of the pole piece, an AC voltage pulse is induced in the wire coil. The Transmission Control Module (TCM) calculates the frequency of these AC pulses and converts it to a speed value. The AC voltage generated varies from 150mV at low speed to 1 SV at high speed. The signal wires from the sensor are formed as twisted pairs to cancel magnetically induced fields. The cable is also shielded to protect from voltage-related fields. Noise from other sources is eliminated by using two-wire differential inputs at the TCM.

CONDITIONS FOR RUNNING THE DTC:
1. The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V TCM).
2. DTC P0716, P0717, or P0722 is not active.
3. Turbine speed is above 200 rpm.
4. Shift is complete and range attained is not neutral.

CONDITIONS FOR SETTING THE DTC:
DTC P0721 is set when one of the following conditions occur:
1. Unrealistic large change in output speed. A Failure pending is set if an unrealistic change in transmission output speed is detected at or above 500 rpm. The failure pending response is to lock in the current range.
2. Noisy output speed signal. Noise is determined with two counters. A low counter is incremented when output speed change is below 500 rpm for 2.5 seconds. A high counter is incremented when output speed change is above 500 rpm. When both counters accumulate 5 events, a failure is set.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0721 is active, the following conditions will occur:
1. If failure occurs while in a forward range and a shift has been completed, the transmission will remain in the current range.
2. If failure occurs while in a forward range and a shift is in progress, the transmission will return to the previous range, except in post-shift state; then the transmission will continue to the commanded range.
3. If failure occurs under other conditions, the transmission shifts to 1st, 3rd, or 5th.
4. If the shift selector is moved to N (Neutral), R (Reverse), or any other forward range, the transmission will lock in N (Neutral).
5. If a latched inhibit is present, the transmission locks to neutral.

DTC P0721 is stored in the TCM history.

The CHECK TRANS light illuminates.

The TCM freezes shift adapts (DNA).

The TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
A Scan Tool may be used to clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

You may have to drive the vehicle in order to experience a fault.

If the condition is intermittent, connect the Scan Tool and select the speed sensor indicated by the code. If the signal is erratic, investigate and eliminate the following:
1. Intermittent wiring connection
2. Excessive vibration (driveline or engine torsionals)
3. Irregular sensor gap (loose sensor, loose tone wheel, or damaged tone wheel

Install a known good speed sensor and see if normal function is restored to rule out an internal short or open in the sensor removed.

Check that the speed sensor wiring consists of twisted pairs at the rate of 12 to 16 twists per 300 mm. These twists must extend the entire length of the wiring harness to within at least 50 mm of the speed sensor connector.

Allison 1000 & 2000 Gen 4 Fault Codes: P0722 Output Speed Sensor Circuit No Signal

CIRCUIT DESCRIPTION:
The speed sensors are variable reluctance devices which convert mechanical motion to an AC voltage. Each sensor consists of a wire coil wrapped around a pole piece that is adjacent to a permanent magnet. These elements are contained in a housing which is mounted adjacent to a rotating ferrous member. Two signal wires extend from one end of the housing and an exposed end of the pole piece is at the opposite end of the housing. The permanent magnet produces lines of flux around the pole piece. As a ferrous object (such as a gear tooth) approaches and passes through the gap at the end of the pole piece, an AC voltage pulse is induced in the wire coil. The Transmission Control Module (TCM) calculates the frequency of these AC pulses and converts it to a speed value. The AC voltage generated varies from 150mV at low speed to 15V at high speed. The signal wires from the sensor are formed as twisted pairs to cancel magnetically induced fields. The cable is also shielded to protect from voltage-related fields. Noise from other sources is eliminated by using two-wire differential inputs at the TCM.

CONDITIONS FOR RUNNING THE DTC:
The components are powered and ignition voltage is greater than 9V and less than 18V (12V TCM) or greater than 18V and less than 32V (24V TCM).

DTC P0716, P0717, P0721, P0731, P0732, P0733, P0734, P0735, P0736, or P1718 is not active.

When unrealistic large change in output speed is detected, output speed is at or above 600 rpm for more than 1 second.

When unrealistically low output speed is detected.
1. Engine is running.
2. Shift is not in process.
3. Range attained is not neutral.
4. Transmission fluid temperature is above -25°C (-13°F).
5. Transmission turbine speed is at or above 1050 rpm.
6. Manual selector valve is not being moved to a forward range.

CONDITIONS FOR SETTING THE DTC:
DTC P0722 is set when one of the following conditions occur:
1. Unrealistic large change in output speed. A failure pending is set if an unrealistic change in transmission output speed is detected at or above 600 rpm. A failure is set if neutral range is attained.
2. Unrealistic low value in output speed. A failure pending is set if output speed is detected below 61 rpm. A failure is set when output speed is below 61 rpm and transmission range is 3rd, 4th, or 5th for more than 1 second.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0722 is active, the following conditions will occur:
1. If failure occurs while in a forward range and a shift has been completed, the transmission will remain in the current range.
2. If failure occurs while in a forward range and a shift is in progress, the transmission will return to the previous range, except in post-shift state; then the transmission will continue to the commanded range.
3. If failure occurs under other conditions, the transmission shifts to 1st, 3rd, or 5th.
4. If the shift selector is moved to N (Neutral), R (Reverse), or any other forward range while the diagnostic response is active, the transmission will lock in N (Neutral).
5. If a latched inhibit is present, the transmission locks in neutral.

DTC P0722 is stored in the TCM history.

The CHECK TRANS light illuminates.

The TCM freezes shift adapts (DNA).

The TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC/CHECK TRANS LIGHT:
A Scan Tool may be used to clear the code from the TCM history. The TCM automatically clears the DTC from the TCM history if the vehicle completes 40 warm-up cycles without the DTC recurring.

DIAGNOSTIC AIDS:
Inspect the wiring for poor electrical connections at the TCM. Look for the following conditions:
1. A bent terminal.
2. A backed-out terminal.
3. A damaged terminal.
4. Poor terminal tension.
5. A chafed wire.
6. A broken wire inside the insulation.

You may have to drive the vehicle in order to experience a fault.

If the condition is intermittent, connect the Scan Tool and select the speed sensor indicated by the code. If the signal is erratic, investigate and eliminate the following:
1. Intermittent wiring connection
2. Excessive vibration (driveline or engine torsionals)
3. Irregular sensor gap (loose sensor, loose tone wheel, or damaged tone wheel

Install a known good speed sensor and see if normal function is restored to rule out an internal short or open in the sensor removed.

Check that the speed sensor wiring consists of twisted pairs at the rate of 12 to 16 twists per 300 mm. These twists must extend the entire length of the wiring harness to within at least 50 mm of the speed sensor connector.

Install a known good TCM, if available. If the DTC does not return, reinstall the old TCM to verify the repair.