P2633 Fuel Pump B Control Circuit Low
OBD-II Trouble Code Technical Description
Fuel Pump B Control Circuit Low
What does that mean?
This is a generic powertrain diagnostic trouble code (DTC) and applies to many OBD-II vehicles (1996-newer). That may include but is not limited to vehicles from Ford, Dodge, Toyota, Chrysler, Jeep, Ram, Chevrolet, Nissan, Mitsubishi, Mercedes, etc. Although generic, the exact repair steps may vary depending on year, make, model and powertrain configuration.
If the P2633 code appears, it means that a problem has been found in the fuel pump "B" control circuit. Specifically it means that a low voltage situation has been detected. Typically, it is brought on by damaged wires/connectors within the circuit or the Controller Area Network (CAN) bus. The Powertrain Control Module (PCM) or the Engine Control Module (ECM) normally identifies this code, however other supporting modules can also spark up this particular code such as:
Alternative Fuel Control Module Fuel Injection Control Module Turbo Control ModuleDepending on the make and model of the vehicle it may be several drive cycles before it is able to activate this code or it can also be an immediate reaction as soon as the ECM recognizes the fault.
The fuel pump is integral in the overall drivability of the vehicle. After all, without the fuel pump, there would be no fuel being delivered to the engine. The control circuit, generally speaking, is responsible for turning the pump on and off depending on the operator's needs. An open within said circuit could also cause the P2633 code to become active so be aware of this before proceeding with any kind of diagnosing.
A typical fuel pump:
Related fuel pump B control circuit codes include:
P2632 Fuel Pump "B" Control Circuit /Open P2633 Fuel Pump "B" Control Circuit Low P2634 Fuel Pump "B" Control Circuit HighWhat is the severity of this DTC?
This particular trouble code is a moderately severe problem for your vehicle. You can still utilize your vehicle despite the problem. However, it is highly advised to avoid doing so, because you may risk intermittently delivering fuel to the engine and an erratic or fluctuating fuel mixture could definitely result in severe engine damage.
What are some of the symptoms of the code?
Symptoms of a P2633 trouble code may include:
The check engine light is illuminated Engine won’t start Engine misfire/stall Engine starts but dies Fuel economy is reduced Engine cranks fine but does not start Engine dies when reaching operating temperatureNote: It is still possible that problem is actually unresolved, even if the check engine light does not light up immediately. Always ensure your vehicle has gone through a few drive cycles. i.e. drive the car for a week, if CEL (check engine light) is not illuminated by the end, the issue is most likely resolved.
What are some of the common causes of the code?
Causes for this code may include:
Issues with the fuel pump itself Severed or damaged ground wire in the device's control module Unattached ground strap in the control module Open, shorted, or corroded wiring in the CAN bus A faulty CAN bus Unsecured harnesses and wires causing a chafe or broken circuit High resistance in circuit (e.g. melted/corroded connectors, internal wire corrosion)What are some P2633 troubleshooting steps?
The first thing I recommend you do is to research the Technical Service Bulletins (TSB's) for the specific vehicle by year, model and power plant. In some circumstances, this can save a lot of time in the long run by pointing you in the right direction.
Basic Step 1
You always should immediately scan and test each module with the use of an OBD-II scanner, to get a good idea of the overall electrical condition of your vehicle an
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