U0588

Code

Generic U — Network/User

Invalid Data Received From Transmission Fluid Pump Module A

Brand: Generic

Type: U — Network/User

Views: UK: 21 EN: 25 RU: 21

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Page language: EN

Causes

Faulty Transmission Fluid Pump Module A (hardware or firmware)
Open, shorted, damaged or corroded wiring/connectors between module and network
Poor or missing power supply or ground to the pump module
CAN/LIN bus faults (missing termination, low/high voltage, interference)
Intermittent connector contact or water intrusion
Software mismatch or corrupted calibration in module or other controllers

Symptoms

Transmission warning or MIL illuminated
Transmission may go into limp mode or have restricted functionality
Incorrect or no pump operation (reduced cooling/pressure)
Abnormal shifting or harsh shifts
Stored and/or repeated communication fault codes

What to check

Read all related U- and P-codes and freeze frame/store data with a capable scan tool
Verify the pump module appears on the network (module present in scan tool list)
Visual inspection of connectors and harness for damage, corrosion, or water intrusion
Check module 12V supply and ground voltages at the module connector
Check CAN/LIN bus voltages and activity with a DVOM or oscilloscope
Wiggle/pressure test wiring harness while monitoring live data for intermittent faults

Signal parameters

Module supply voltage: ~12 V (check for battery voltage at key-on and running)
Module ground: near 0 V (low resistance to chassis ground)
CAN bus idle voltages: CAN_H ≈ 2.5 V, CAN_L ≈ 2.5 V (recessive); dominant typically CAN_H ≈ 3.5 V, CAN_L ≈ 1.5 V
Typical CAN bus data rates: commonly 250 kbps or 500 kbps depending on vehicle
Module messages: periodic status/telemetry packets (expected regular interval; absence or corrupted payload flags fault)
Checksum/CRC or counter fields present in messages — invalid or out-of-range values indicate corrupted data

Diagnostic algorithm

Retrieve and record all current and historic DTCs, freeze frame and live data for the pump module and related controllers.
Clear codes and attempt to reproduce the fault with the engine and transmission at normal operating conditions.
Confirm the pump module is present on the vehicle network using a scan tool; note whether it responds to requests and shows valid parameters.
Perform a visual inspection of the module connector and harness; repair any corrosion, bent pins, or physical damage.
Backprobe the module connector and verify key-on and running power and ground with a DVOM; repair any supply issues.
Monitor CAN bus voltages and signal integrity with an oscilloscope at the module connector while operating; verify correct idle levels and message activity.
If the bus looks unhealthy, isolate segments (disconnect the module) and test for bus termination or a short to battery/ground.
Wiggle the harness and connectors while monitoring live data to find intermittent faults.
If wiring and power/ground are good and communications are still invalid, check for and apply any available software updates or reflash the pump module and vehicle controllers per manufacturer procedures.
If software update and diagnostics do not restore valid data, replace the Transmission Fluid Pump Module A and re-test. After repair, erase codes and verify normal operation and no reoccurrence.

Likely causes

Damaged connector or wiring to the pump module
Module lost power or ground intermittently
CAN bus voltage out of range (bus off, missing termination)
Faulty pump module firmware or internal failure

Fault status

⚠️ Status

Invalid data received from Transmission Fluid Pump Module A. The module is not sending valid communication or its messages are corrupted. This can affect transmission cooling/pressure control and may require wiring, module, or software repair.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.0-4.0 hours