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Generic P — Powertrain

Charge Air Cooler Coolant Pump B Control Circuit/Open

Brand: Generic

Type: P — Powertrain

Views: UK: 31 EN: 31 RU: 26

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Page language: EN

Causes

Open or damaged wiring in the pump B control circuit
Corroded or loose connector at the pump or PCM
Failed charge air cooler coolant pump (pump motor or internal wiring)
Blown fuse or faulty relay supplying the pump
Short to voltage or short to ground in control wiring
High-resistance ground or supply

Symptoms

Malfunction Indicator Lamp (MIL) / check engine light illuminated
Charge air cooler (intercooler) coolant not circulating on pump B circuit
Possible elevated charge-air temperatures, turbo inefficiency or reduced performance
Possible engine derate or limp mode on some vehicles
No audible pump operation when pump is commanded

What to check

Read freeze-frame and live data with a scan tool; verify pump B commanded status
Attempt an active test (command pump B on) from a capable scan tool and observe response
Visually inspect wiring and connectors for corrosion, damage, water ingress, or loose pins at pump and PCM
Check relevant fuses and relays for continuity and correct operation
Measure supply voltage and ground at the pump connector with key ON and while pump is commanded
Measure pump motor resistance and test pump by applying known good bench power (observe current draw)

Signal parameters

Supply voltage to pump: nominal battery voltage (~12 V) at supply pin when key ON
Control signal: typically a switched ground or switched 12 V from PCM (may be PWM on some vehicles)
Active control state: control line will change to the active state when PCM commands the pump (0 V if ground-switched or ~12 V if switched high)
Pump current draw: varies by design but commonly in the range of hundreds of milliamps to several amps; significant change from expected indicates pump fault or short
Pump motor DC resistance: vehicle-specific; expect a low-ohm value for a healthy motor (no open circuit)

Diagnostic algorithm

Retrieve freeze frame and stored data. Note conditions when code set and identify whether pump B was commanded.
Perform an active command for pump B with a scan tool. Listen/feel for pump operation and note any change in live data.
Visually inspect connectors at pump B and PCM for corrosion, bent pins, or water intrusion. Repair or reseat as needed.
Check related fuses and relays; replace any blown or suspect items and retest.
With key OFF, disconnect the pump connector. Measure DC resistance of the pump motor. If open circuit, suspect failed pump.
Apply battery voltage directly to the pump (bench test) to confirm mechanical/electrical operation. If pump runs, focus on vehicle wiring/controls.
With connector connected, backprobe supply and control pins. With key ON and pump not commanded, verify supply voltage present and control in inactive state. Command pump ON and verify control changes to active state and pump receives power/ground.
If control does not change when commanded, check continuity of control conductor to PCM. Repair any opens/shorts found.
If wiring and pump check good but PCM does not command or drive the circuit correctly, consider PCM output driver fault; consult manufacturer guidance before replacing ECM/PCM.
After repairs, clear codes and perform road/operational test to confirm code does not return under the original conditions.

Likely causes

Broken or disconnected connector at the pump
Damaged wire (chafing, pinched, rodent damage) in harness to pump B
Failed pump motor or internal connector
Blown fuse or failed relay feeding the pump

Fault status

⚠️ Status

Charge Air Cooler Coolant Pump B Control Circuit/Open - PCM detects an open or abnormal signal on the pump B control circuit indicating the pump may not be receiving proper drive or the circuit has high resistance or an open.

🟡 Repair difficulty: Medium

⏱️ Diagnostic time: 0.5-2.5 hours