Transmission Fluid Auxiliary Pump
Authoring Template
Transmission Fluid Auxiliary Pump
| Item | Description |
|---|---|
| 1 | Bolts (2 required) |
| 2 | Transmission fluid auxiliary pump |
| 3 | Seal |
| 4 | Torque converter housing |
| 5 | Transmission case |
On vehicles equipped with Auto-Start-Stop, the transmission is equipped with a transmission fluid auxiliary pump. The electronic pump can be turned on before an engine stop event, allowing the transmission to stay engaged during the stop event. This allows quick response on the engine restart because the transmission is already in gear. The transmission fluid auxiliary pump does not have sufficient flow to apply clutches, but can keep clutches on when the engine stops and the main hydraulic pump stops providing pressure.
Normal Operation and Fault Conditions
The electric transmission fluid pump keeps the transmission fluid circulating during extended drive times without engine charging. The electric transmission fluid pump has an internal microprocessor and communicates with the PCM over a PWM circuit with a frequency of 150 Hz with a duty cycle range of 10% to 90%. If the transmission fluid level is low or overfilled or there are any restrictions in the transmission lines, hoses (if vehicle is equipped with external lines or hoses) or cooler it may affect the transmission fluid pump operation.
| DTC | Duty Cycle Range | Condition |
|---|---|---|
| P0C2D | Less than 10% | Out of range Low |
| P0C27 | 10% to 15% | Pump current too Low, Speed OK |
| P0C28 | 20% to 25% | Pump Current Too High, Speed OK |
| P175A | 30% to 34% | Pump Over Temperature |
| P0C2A | 35% to 40% | Pump Stalled |
| NONE | 44% to 50% | EVERYTHING IS OK - NORMAL VALUE OF SIGNAL |
| P0B0D | 55% to 60% | Pump Over Speed - current OK |
| P0B0D | 65% to 70% | Pump Under Speed - current OK |
| P0C29 | 75% to 80% | Both Current and Speed out of range |
| P2796 | 85% to 90% | No Command received from Control Module |
| P0C2E | Greater than 90% | Duty Cycle Out of range HI - undefined |
| P0C2C | Any other value (between) | Invalid duty cycle or invalid frequency. This could include no signal. |
DTC Fault Trigger Conditions
| DTC | Description | Fault Trigger Conditions |
|---|---|---|
| P0B0D | Electric Transmission Fluid Pump Motor Control Module | This DTC sets if the E-pump communication is OK. The frequency is between 130 Hz and 170 Hz and a valid duty cycle was detected (55% to 60% or 65% to 70%). The transmission fluid pump has detected a pump over or under speed condition. The current flow through the pump was within specification. |
| P0C27 | Electric Transmission Fluid Pump Motor Control Module | Possible causes are loss of pump prime or low transmission fluid level. This DTC sets if the E-pump communication is OK. The frequency is between 130 Hz and 170 Hz but a low current is detected (10% to 15% duty cycle). |
| P0C28 | Electric Transmission Fluid Pump Motor Current Low | This DTC sets if the E-pump communication is OK. The frequency is between 130 Hz and 170 Hz but a low current is detected (20% to 25% duty cycle). |
| P0C29 | Electric Transmission Fluid Pump Motor Current High | This DTC sets if the E-pump communication is OK. The frequency is between 130 Hz and 170 Hz but a high current is detected. |
| P0C2A | Electric Transmission Fluid Pump Motor Stalled | This DTC sets if the PCM commands the electric transmission fluid pump motor on and does not detect a corresponding increase in pump speed, indicating a stalled pump motor. |
| P0C2C | Electric Transmission Fluid Pump Control Module Feedback Signal Range/Performance | This DTC sets if the E-Pump frequency is between 125 and 175Hz but has an invalid duty cycle or the frequency is outside of the 125-175Hz range. This can be caused by a loss of power to the E-Pump. |
| P0C2D | Electric Transmission Fluid Pump Control Module Feedback Signal Low | This DTC sets if the duty cycle is less than 10%. |
| P0C2E | Electric Transmission Fluid Pump Control Module Feedback Signal High | This DTC sets if the duty cycle is greater than 90%. |
| P175A | Transmission Fluid Over Temperature Condition - Electric Transmission Fluid Pump Disabled | This DTC sets if the E-pump communication is OK. The frequency is between 130 Hz and 170 Hz but an over temperature condition is detected (30% to 34% duty cycle). This DTC can be caused by high transmission fluid temperatures |
| P2796 | Electric Transmission Fluid Pump Control Circuit | This DTC sets when the electric transmission oil pump reports to the PCM that it is not receiving a PWM from the PCM. |