Allison

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 located 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 TCM calculates the frequency of these AC pulses and converts it to a speed value. 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. DTC P0722 is set by an unrealistic large change in output speed or unrealistic low value in output speed.

ACTION TAKEN WHEN THE DTC SETS:
When the DTC P0722 is active, the following conditions occur:
1. If failure occurs while in a forward range and a shift has been completed, the transmission remains in the current range.
2. The TCM forces Variable Modulated Main off.
3. 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 continues to the commanded range.
4. If failure occurs under other conditions, the transmission shifts to 1st, 3rd, or 5th.
5. If the shift selector is moved to N (Neutral), R (Reverse), or any other forward range, the transmission will lock in neutral.
6. If a latched inhibit is present, the transmission locks to neutral.

DTC P0722 is stored in the TCM history.

The TCM freezes shift adapts (DNA).

The CHECK TRANS light illuminates (non-OBD II strategy).

The TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool to clear the DTC 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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and therefore should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

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 diagnostic tool and select the speed sensor indicated by the DTC. 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 (12 inches). These twists must extend the entire length of the wiring harness to within at least 50mm (2 inches) 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.

CIRCUIT DESCRIPTION:
The speed sensors are devices which convert mechanical motion to an electrical signal. This test detects an output speed sensor circuit short to battery, ground, or open.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0720 is active, the following conditions occur:
1. DTC P0725 is stored in the TCM history.
2. The TCM does not illuminate the CHECK TRANS light.
3. If ignition is OFF, then engine speed is set to 0. If turbine shaft speed is greater than the engine speed calibration default value, then substitute turbine shaft speed as engine speed.

CONDITIONS FOR CLEARING THE DTC:/CHECK TRANS LIGHT
Use the diagnostic tool to clear the DTC 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:
DTC P0725 may be caused by:
1. W139 and/or W159 shorted to another wire in chassis harness or to ground.
2. W139 and/or W159 high resistance or open circuit.
3. Broken or defective connector assemblies allowing pushed back pins to short together.
4. Unlocked connectors, missing seal plugs allowing moisture in connectors.
5. Fatigued wires at speed sensor connectors (broken strands).
6. Incorrect pin crimps or expanded terminals.
7. Defective engine speed sensor.
8. Defective TCM.
9. Wire pair not twisted or not sufficiently twisted.

NOTE: Inspect 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.

NOTE: The OEM transmission warranty, or the extended coverage for parts and labor, does not cover the repair or replacement of OEM or bodybuilder-provided components or any external wire harnesses not provided by the OEM.

Before repairing or replacing these components or circuits that caused a transmission issue, always contact the vehicle OEM call center and/or the vehicle OEM or bodybuilder service representative to verify the warranty coverage and proper payment arrangements, arrange an alternate sublet or repair plan (if needed), and get troubleshooting assistance for the repair (such as vehicle schematics, DTC trees, parts assistance, etc).

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 located 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 TCM calculates the frequency of these AC pulses and converts it to a speed value. 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. DTC P0726 is set by an unrealistic large change in output speed or unrealistic low value in output speed.

ACTION TAKEN WHEN THE DTC SETS:
1. DTC P0726 is stored in the TCM history.
2. The CHECK TRANS light is not illuminated.
3. The TCM defaults engine speed to turbine speed. Turbine speed is used to determine the missing engine speed.
4. The TCM forces Variable Modulated Main off.

CONDITION FOR CLEARING THE DTC
Use the diagnostic tool to clear the DTC 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:
The following procedures are not documented in any OEM procedures or in any OEM Troubleshooting or Service information and should not be used as a method to diagnose any transmission DTCs, function, or shift quality concern:

1. Back-probing any connections used for transmission features or functions may damage and/or unlock terminals from the back-probed connector creating permanent or intermittent shorts and/or open circuits. If possible, use the J-39700 Breakout Box, the appropriate harness adapters, and appropriate magnetic overlays to troubleshoot the vehicle.

2. Load-testing any transmission-related circuits with any other electrical devices such as vehicle lamps or relays, especially with the TCM connected to the harness. Use J-39700 Breakout Box and appropriate harnesses with the diagnostic tool to monitor the circuit performance in question unless otherwise specified in the various Troubleshooting information.

3. Piercing a wire to check for voltages, shorts-to-grounds or other wires anywhere in the circuit but especially at the TCM. This creates a leak path for moisture and damages the wire and insulation.

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 diagnostic tool and select the speed sensor indicated by the DTC. 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 (12 inches). These twists must extend the entire length of the wiring harness to within at least 50 mm (2 inches) 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.

CIRCUIT DESCRIPTION:
The TCM uses input from the turbine speed and the output speed sensors to determine the current commanded steady state gear ratio. The TCM then compares the known gear ratio to the calculated gear ratio for the current range. DTC P0729 sets during steady state condition when the calculated sixth gear ratio differs from the known sixth gear ratio for a calibrated time.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0729 is active, the following conditions occur:
1. A shift to 5th range is made when the failure occurs.
2. While diagnostic response is active, if shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Reverse), transmission shifts to neutral. If the shift selector is moved to D (Drive) range and transmission is compromised by overspeeding or direction change, transmission shifts to neutral.
3. DTC P0729 is stored in the TCM history.
4. The CHECK TRANS light illuminates (non-OBD II strategy).
5. The TCM forces Variable Modulated Main off.
6. TCM freezes shift adapts (DNA).
7. TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool to clear the DTC 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 or diagnostic tool for a change.

Output or turbine tone wheel damage may cause erratic speed sensor input allowing this DTC to set.

Use the diagnostic tool to record a snapshot of the occurrence, monitor the engine, turbine and output speed signal on the strip chart. Look for erratic or noisy signals, which may indicate an intermittent concern at one of the speed sensor circuits.

Drive the vehicle in 4th range where signals are the same to better determine if signals have a problem.

You may have to clear the DTC and drive the vehicle in order to experience a fault. Use the data obtained from failure records to determine transmission range and/or certain vehicle operating variables such as temperature, run time etc. This data can be useful in reproducing failures mode where DTC was set.

Incorrect ratio DTCs typically indicate mechanical problems with specific clutches for range indicated.

An incorrect ratio DTC may indicate a mechanically failed trim solenoid. Check the DTC information for the specific solenoid.

Incorrect TCM calibration causes this DTC to set. Verify the Calibration Identification Number (CIN) is compatible with the model of transmission installed in vehicle.

CIRCUIT DESCRIPTION:
The TCM uses input from the turbine speed and the output speed sensors to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current range. DTC P0731 sets when the calculated 1st range ratio (steady state) differs from the known 1st range ratio.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0731 is active, the following conditions occur:
1. The transmission fails to 2nd range.
2. If shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Reverse), transmission shifts to reverse unless the transmission is compromised by overspeeding or direction change, then it locks in N (Neutral).
3. DTC P0731 is stored in the TCM history.
4. The CHECK TRANS light illuminates (non-OBD II strategy).
5. The TCM forces Variable Modulated Main off.
6. TCM freezes shift adapts (DNA).
7. TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC:
The diagnostic tool may be used to clear the DTC 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 speed sensor wiring and connectors for poor electrical connections. 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 or the diagnostic tool for a change.

Output or turbine tone wheel damage may cause erratic speed sensor input allowing this DTC to set.

Incorrect ratio DTCs typically indicate mechanical problems with specific clutches, i.e. C1 or C5 for 1st range.

An incorrect ratio DTC could indicate a hydraulically failed solenoid. Check the DTC information for the specific solenoid.

You may have to drive the vehicle to experience the fault.

Incorrect ratio DTCs typically indicate mechanical problems with specific clutches for range indicated.

Clutch test mode can be used to detect turbine pull-down. If turbine speed is detected, clutch damage may be indicated.

Incorrect TCM calibrations cause this DTC to set. Verify the proper TCM calibration is being used with the correct transmission family. There are different gear ratios for the 1000 and 2000 OEM transmissions.

NOTE: Transmissions equipped with Neutral at Stop could create this code if there is a stuck Neutral at Stop Pressure Control Valve (PCV) or a stuck PCS3 (Neutral at Stop only).

CIRCUIT DESCRIPTION:
The TCM uses input from the turbine speed and the output speed sensors to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current range. DTC P0732 sets when the calculated 2nd range ratio (steady state) differs from the known 2nd range ratio.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0732 is active, the following conditions occur:
1. The transmission fails to 3rd range.
2. If shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Reverse), transmission shifts to reverse unless the transmission is compromised by overspeeding or direction change, then it locks in N (Neutral).
3. DTC P0732 is stored in the TCM history.
4. The CHECK TRANS light illuminates (non-OBD II strategy).
5. The TCM forces Variable Modulated Main off.
6. TCM freezes shift adapts (DNA).
7. TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC::
Use the diagnostic tool to clear the DTC 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 speed sensor wiring and connectors for poor electrical connections. 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 or diagnostic tool for a change.

Output or turbine tone wheel damage may cause erratic speed sensor input allowing this DTC to set.

Incorrect ratio DTCs typically indicate mechanical problems with specific clutches, i.e. C1 and C4 for 2nd range.

An incorrect ratio DTC could indicate a hydraulically failed solenoid. Check the DTC information for the specific solenoid.

You may have to drive the vehicle to experience the fault. Clutch test mode can be used to check stall speed.

Incorrect TCM calibrations cause this DTC to set. Verify the proper TCM calibration is being used with the correct transmission family. There are different gear ratios for the 1000 and 2000 OEM transmissions.

NOTE: Transmissions equipped with Neutral at Stop could create this code if there is a stuck Neutral at Stop Pressure Control Valve (PCV) or a stuck PCS3 (Neutral at Stop only).

CIRCUIT DESCRIPTION:
The TCM uses input from the turbine speed and the output speed sensors to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current range. DTC P0733 sets when the calculated 3rd range ratio (steady state) differs from the known 3rd range ratio.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0733 is active, the following conditions occur:
1. The transmission fails to 4th range.
2. If shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Reverse), transmission shifts to reverse unless the transmission is compromised by overspeeding or direction change, then it locks in N (Neutral).
3. DTC P0733 is stored in the TCM history.
4. The CHECK TRANS light illuminates (non-OBD II strategy).
5. The TCM forces Variable Modulated Main off.
6. TCM freezes shift adapts (DNA).
7. TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool to clear the DTC 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 speed sensor wiring and connectors for poor electrical connections. 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 or diagnostic tool for a change.

Output or turbine tone wheel damage may cause erratic speed sensor input allowing this DTC to set.

Incorrect ratio DTCs typically indicate mechanical problems with specific clutches, i.e. C1 and C3 for 3rd range.

An incorrect ratio DTC could indicate a hydraulically failed solenoid. Check the DTC information for the specific solenoid.

You may have to drive the vehicle to experience the fault. Clutch test mode can be used to check stall speed.

Incorrect TCM calibrations cause this DTC to set. Verify the proper TCM calibration is being used with the correct transmission family. There are different gear ratios for the 1000 and 2000 OEM transmissions.

NOTE: Transmissions equipped with Neutral at Stop could create this code if there is a stuck Neutral at Stop Pressure Control Valve (PCV) or a stuck PCS3 (Neutral at Stop only).

CIRCUIT DESCRIPTION:
The TCM uses input from the turbine speed and the output speed sensors to determine gear ratios. The TCM then compares the known gear ratio to the calculated gear ratio for the current range. DTC P0734 sets when the calculated 4th range ratio (steady state) differs from the known 4th range ratio.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P0734 is active, the following conditions occur:
1. The transmission fails to 5th range.
2. If shift selector is moved to N (Neutral), transmission shifts to neutral; if the shift selector is moved to R (Reverse), transmission shifts to reverse unless the transmission is compromised by overspeeding or direction change, then it locks in N (Neutral).
3. DTC P0734 is stored in the TCM history.
4. The CHECK TRANS light illuminates (non-OBD II strategy).
5. The TCM forces Variable Modulated Main off.
6. TCM freezes shift adapts (DNA).
7. TCM inhibits TCC engagement.

CONDITIONS FOR CLEARING THE DTC:
Use the diagnostic tool to clear the DTC 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 speed sensor wiring and connectors for poor electrical connections. 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 or diagnostic tool for a change.

Output or turbine tone wheel damage may cause erratic speed sensor input allowing this DTC to set.

Incorrect ratio DTCs typically indicate mechanical problems with specific clutches, i.e. C1 and C2 for 4th range.

An incorrect ratio DTC could indicate a hydraulically failed solenoid. Check the DTC information for the specific solenoid.

You may have to drive the vehicle to experience the fault.

Clutch test mode can be used to detect turbine pull-down. If turbine speed is detected, clutch damage may be indicated.

NOTE: Transmissions equipped with Neutral at Stop could create this code if there is a stuck Neutral at Stop Pressure Control Valve (PCV) or a stuck PCS3 (Neutral at Stop only).