How severe is this DTC?
This particular fault code is a moderately serious issue for your vehicle. You can still use your vehicle despite the problem. However, it is strongly advised not to do so, as you risk intermittently supplying fuel to the engine, and an erratic or fluctuating fuel mixture could permanently cause severe engine damage.
What are some of the symptoms of the code?
Symptoms of a P2633 fault code may include:
- Check engine light is on
- Engine does not start
- Engine misfires/stalling
- Engine starts but dies
- Fuel economy is reduced
- Engine cranks but does not start
- Engine dies when reaching operating temperature
Note: It is always possible that the problem is not resolved, even if the check engine light does not come on immediately. Always ensure your vehicle has undergone a few driving cycles, i.e., drive the car for a week; if the CEL (check engine light) is not on by the end, the issue is most likely resolved.
What are some common causes of the code?
Causes
of this code may include:
- Issues with the fuel pump itself
- Cut or damaged ground wire in the device control module
- Unsecured ground strap in the control module
- Open, shorted, or corroded wiring in the CAN bus
- A faulty CAN bus
- Unsecured harness and wires causing chafing or a broken circuit
- High resistance in the circuit (e.g., melted/corroded connectors, internal wire corrosion)
What are the troubleshooting steps for P2633?
The first thing I recommend doing is searching for Technical Service Bulletins (TSBs) for the specific vehicle by year, model, and powertrain. In some cases, this can save you a lot of time in the long run by pointing you in the right direction.
Basic Step 1
You should always scan and immediately test each module using an OBD-II scanner to get a good idea of the overall electrical state of your vehicle and its modules. You should also always perform a visual inspection of connectors and wiring in case something is obviously damaged, in which case it should be repaired or replaced. Often, these are located under the vehicle near the fuel tank. They are sensitive to road debris and the elements, so pay close attention to their condition.
Basic Step 2
When dealing with a component that has its own module (e.g., fuel pump module, etc.), you need to check the ground circuits. You can do this using a separate battery ground. Sometimes, you can do this easily with an auxiliary ground cable. If your issue is resolved with the auxiliary ground attached but returns when the OEM ground is used, it means your ground cable is the source of the problem and needs to be repaired or replaced. Grounds should always be carefully inspected for corroded connections, terminals, pins, etc., that could be causing circuit resistance. A good sign of excessive corrosion is a green ring around the connector attached to the positive battery terminal. If this is present, remove the terminal and clean all contact points, the face of the connector, and the terminal/stud.
Basic Step 3
Since the cause of the P2633 code could be an open circuit, you need to identify the circuit using an electrical wiring diagram from your service manual. Once identified, you can individually trace the fuel pump control wire A to see if there are any obvious breaks in the wire. Repair as necessary by soldering the wire (which I recommend) or using butt connectors with heat shrink to insulate it from the elements. Using your multimeter, you can measure the resistance between the circuit connectors to locate the short/open circuit location. A power probe-style tool is highly recommended here if there is a fault somewhere within the entire circuit.
I hope this article has been helpful in guiding you in the right direction to diagnose the issue with your fuel pump control circuit fault code. This article is strictly informational, and technical data and service bulletins specific to your vehicle should always take priority.