P0C1B

Code

Generic P — Powertrain

Electric/Auxiliary Transmission Fluid Pump Control Module Internal Temperature Too High

Brand: Generic

Type: P — Powertrain

Views: UK: 38 EN: 45 RU: 31

AI status

Completed

ready

Completed 100%

Page language: EN

Causes

Actual overheating of the pump or control module (excessive load, high ambient or restricted fluid flow)
Low or contaminated transmission fluid causing poor cooling
Blocked fluid passages, clogged cooler or heat exchanger
Stalled or mechanically binding pump increasing heat load
High electrical current draw to the pump (shorts, seized motor, incorrect voltage)
Faulty internal temperature sensor in the pump/control module

Symptoms

Transmission warning light or POST message
Reduced transmission performance or limp-in mode
Loss of drive or delayed/harsh shifting
Unusual noise from pump area (grinding or whining)
Elevated transmission temperature readout (if available)
Blown fuses or tripped thermal protection in extreme cases

What to check

Read DTCs and freeze frame/scan tool data; note reported internal temperature and operating conditions when fault stored
Visually inspect pump, control module and wiring for heat damage, corrosion, loose connectors or fluid contamination
Check transmission fluid level, color and smell (burnt odor); sample fluid if suspect
Check for blocked cooler lines, collapsed hoses or restricted cooler core
Verify battery voltage and ground at the pump module with engine running and during pump activation
Monitor pump current draw and module temperature data with a scan tool or clamp meter

Signal parameters

Module supply voltage: nominal battery/charging system (typically ~12–14.5 V while running)
Module ground: low resistance to chassis ground
Internal temperature sensor output: typically an analog signal (0–5 V) or resistance that varies with temperature — verify against OEM chart
Pump motor current draw: varies by vehicle/pump design (common range under load is single digits to tens of amps) — compare to service spec
CAN/communication status: module should respond on network with current temp and status data

Diagnostic algorithm

Retrieve all active and pending codes plus freeze frame using a capable scan tool. Note operating conditions (vehicle speed, engine rpm, ambient temp).
Visually inspect pump, control module, harness and connectors for heat damage, melted insulation, corrosion, fluid intrusion or loose pins. Repair or secure as needed.
Check transmission fluid level and condition. If low or contaminated, address fluid/flow issues before further electrical diagnosis.
With a scan tool, monitor the pump/module internal temperature parameter and pump current while cycling pump function if service procedures allow. Compare values to expected behaviour.
Measure module supply voltage and ground under load. Look for voltage drop or poor ground which can cause overheating or erroneous readings.
If the module provides a temperature sensor signal (voltage or resistance), verify sensor circuit integrity and compare values to the OEM temperature chart. Replace sensor/module if out of range.
Measure pump motor current with a clamp meter during operation and compare to spec. High current indicates mechanical binding or motor fault; low/zero indicates open circuit or failed motor.
Inspect and test cooler lines and cooler for blockage; flush or replace as required. Verify fluid flow through the pump and cooler.
Repair or replace damaged wiring, connectors, pump or control module as indicated by tests. Clear codes, then perform operational test/road test to confirm fault does not return.
If module replacement is required, follow OEM programming/learning procedures for TCM/ECM/module initialization where applicable.

Likely causes

Actual pump/control module overheating due to low/dirty fluid or restricted cooler
High current draw from a failing or binding pump motor
Faulty internal temperature sensor or module electronics
Poor power/ground or damaged wiring causing module heat or false readings

Fault status

⚠️ Status

Internal temperature of the electric/auxiliary transmission fluid pump control module has exceeded the permitted threshold or the module reports an over-temperature condition. May cause reduced transmission function or protective shutdown.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 1.5-4.0 hours