Allison 3000 & 4000 Gen 4 Fault Code: P070D Transmission Fluid Level Sensor Circuit High Input

DIAGNOSTIC RESPONSE:
None

CIRCUIT DESCRIPTION:
The Oil Level Sensor (OLS) uses an internal float and internal hall effect sensor to provide voltage to the TCM that is proportional to the sensor detected float level and current fluid level. The TCM provides a 5V reference voltage to the OLS.

NOTE: The OLS is standard on any 3000 and 4000 Product Families 4th Generation Controls transmissions except for the 3700SP or any of the 4700/4800 retarder models where it is unavailable.

NOTE: The TCM calibration is specified to always autodetect the OLS; however, re-programming the CMC ‘Override Oil Level Sensor’ to ‘Present’ or ‘Not Present’ is also an option for a customer who may not want to replace a defective sensor or one who wants to determine if the TCM or calibration is operating correctly.

The TCM is connected to the OLS by:
1. A 5V reference voltage (W112),
2. OLS signal (W116)
3. Analog ground (W158).

The TCM interprets this proportional voltage signal on W116 as oil level counts which is then converted to millimeters of fluid level. The fluid level reading is then converted to liters of quarts of oil level deviation (+/-) that can be viewed using the diagnostic tool data monitor.

NOTE: Check that there are no active oil level display code inhibits (such as settling time not equal to zero, not Neutral, high output speed, and low oil temperature) prior to relying on the oil level deviation amount shown in the diagnostic tool data monitor. Do not rely on the oil level deviation readings if one of the inhibits is active.

CONDITIONS FOR RUNNING THE DTC:
1. The OLS must be autodetected or set to ‘Present’ by the CMC ‘Override Oil Level Sensor’.
2. TCM initialized and engine speed above 500 rpm.
3. DTC test will run at one second intervals.

CONDITIONS FOR SETTING THE DTC:
DTC P070D sets if the OLS signal voltage (sensor voltage in the diagnostic tool data grid) is more than 5V six times or more within twenty-six seconds.

ACTION TAKEN WHEN THE DTC SETS:
When DTC P070D is active, the following conditions occur:
1. The TCM does not illuminate the CHECK TRANS light.
2. DTC is stored in TCM history.
3. Fluid level may not be checked with the OLS.

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 forty warm-up cycles without failure.

DIAGNOSTIC AIDS:
NOTE: The OLS has an integrated hall effect sensor; it cannot be checked for defect by measuring resistance. The OLS may be damaged using a continuity tester or continuity check function using a DMM. Damage to the OLS occurs if 12V is applied to the OLS.

DTC P070D indicates the TCM has detected a voltage signal from the OLS in the high error zone. This may be caused by the following:
1. Short to battery in W112 or W116 circuits.

NOTE: Shorts to battery in W112 typically will log other sensor failed high DTCs that are using W112 (5V), such as the analog TPS, Electronic Brake System (EBS) pressure sensor, or Retarder Modulation Request (RMR) sensor, Shorts to battery in W116 (OLS signal) only causes DTC P070D.

2. Non-OLS application has been autodetected or programmed to ‘Present’ by the CMC ‘Override Oil Level Sensor’ as having an OLS when an OLS is not installed and W116 or W112 is shorted to is shorted to battery.
3. Defective OLS.
4. Defective sensor sharing 5V supply with OLS.
5. 5V wire shorted to battery in transmission internal harness or chassis harness.
6. TCM issue.
7. Transmission Overfilled.
8. W158 high resistance or open.

OLS voltage (signal voltage on W116) is available on the diagnostic tool data monitor grid. Prior to ‘Connect’ for the diagnostic tool, check the ‘Troubleshoot Specific Problem’ box under the “connection options” and then check the ‘Sensor, Voltage, Ohms, and Counts Data’ box.

The J-39700 Universal Breakout Box may also be used to acquire OLS signal (sensor) voltage on W116. The data monitor values for ‘Oil Level Sensor Voltage’ and ‘Oil Level Deviation’ should be checked with the TCM initialized, engine running, and transmission in N (Neutral). Transmission fluid temperature must be over the minimum threshold before noting the ‘Oil Level Deviation’ amount. Both values are useful for troubleshooting OLS performance by:

1. If the sensor signal voltage does not meet requirements shown in “Conditions for Setting the DTC”.
2. How the oil level deviation changes when a known quantity of oil is added or removed from the transmission.

Review applicable information in Control System and Transmission Specifications to find additional circuit specifications, system and connector diagrams, and troubleshooting tips.