Allison 1000 & 2000 Gen 5 Fault Code:P0727 Engine 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 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 P0727 is stored in the TCM history.
2. The CHECK TRANS is not illuminated.
3. The TCM forces Variable Modulated Main off.
4. The TCM defaults engine speed to turbine speed. Turbine speed is used to determine the missing engine speed.
5. TCM inhibits TCC momentarily.
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 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 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.
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 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.
Related
-
VOLVO PREMIUM TECH TOOL PTT 2.7.30 Developer + Devtool + INSTALATION VIDEO!
Trucks software $60.00Rated 0 out of 5 -
ddct Detroit diesel calibration tool (DDCT) v4.5 English Include Calibrations & Metafiles
Detroit $30.00Rated 0 out of 5 -
John Deere & Hitachi Parts ADVISOR 2020 [08.2020] Offline DVD Spare Parts Catalog
John Deere $120.00Rated 0 out of 5
-
CLAAS WebTIC Offline [11.2021] Service Information – ENGLISH Language
CLAAS $100.00Rated 0 out of 5 -
Detroit Diesel Diagnostic Link DDDL 8.0 PRO PROFESSIONAL Software trucks
Detroit $25.00Rated 0 out of 5 -
John Deere & Hitachi Parts ADVISOR 2020 [08.2020] Offline DVD Spare Parts Catalog
John Deere $120.00Rated 0 out of 5 -
Bobcat Service Library [03.2019] Service, Operator, Maintenance, Bulletines, etc full update
Bobcat $110.00Rated 0 out of 5 -
DPF EGR SCR BAC ERG Delete & Flash CAAT Cummings Detroit Dodge Mack Volvo Collection of DELETE files
CAT $200.00Rated 0 out of 5
Related products
-
Allison 1000 & 2000 Gen 4 Fault Codes: P0880 TCM Supply Voltage
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0122 Pedal Position Sensor Circuit Low Voltage
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P2810 Solenoid G Electrical
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U2104 CAN Bus Reset Counter Overrun
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0875 Transmission Reverse Pressure Switch Circuit Malfunction
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0870 Transmission Pressure Switch Solenoid E Circuit
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0872 Transmission Pressure Switch Solenoid E Circuit Stuck Closed
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U1041 J1850 (Class 2) ABS Controller State of Health Failure
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U2105 CAN Bus ECM Error
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U1064 J1850 (Class 2) TBC Controller State of Health Failure
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0846 Transmission Pressure Switch Solenoid D Circuit Stuck Open
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U1016 Class 2 J1850 (Class 2) Powertrain Controller State of Health Failure
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0876 Transmission Reverse Pressure Switch Circuit Stuck Open
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: P0123 Pedal Position Sensor Circuit High Voltage
1000 & 2000 Gen 4 $50.00Rated 0 out of 5 -
Allison 1000 & 2000 Gen 4 Fault Codes: U0032 J1850 (Class 2) Serial Data Communication Link High
1000 & 2000 Gen 4 $50.00Rated 0 out of 5
-
SERVICE MANUAL Eaton Gen III Automated TransmissionsTRSM0930 EN-USOctober 2020
TRUCK MANUALS $24.00Rated 0 out of 5