The fuel system in modern GM Chevrolet Silverado vehicles is controlled by microprocessor-based electronic devices called fuel pump control modules.
The fuel pump control module (FPCM) is an electronic replacement of a traditional fuel pressure regulator.
If you are getting error code P069E on your dash panel, it indicates that the fuel pump control module has detected an issue with the fuel system and has sent a feedback signal to the ECM to turn on the check engine light.
If your vehicle is not starting and there is apprehension of a faulty fuel pump control module and thinking of a Silverado fuel pump control module bypass, then you are at the right place.
For Silverado fuel pump control module bypass, you need to simply take a jumper wire and connect the hot-wired battery source pin port 16 to the fuel pump control module ground pin port 1 and the incoming power source pin port 32 to the fuel pump positive pin port 47 of the fuel pump control module.
If you are looking for a detailed explanation of the Silverado fuel pump control module bypass, then you are at the right place. Stay tuned!
Table Of Contents
How Fuel Pump Control Module Works?
In the case of a fuel system with a fuel pressure regulator, the fuel pump continuously supplies high-pressure fuel to the engine.
But once the pressure increases higher than predefined levels the fuel pressure regulator opens and leaks back fuel to the fuel tank.
The reason for the introduction of the fuel pump control module is to ensure that the engine control module has more control over fuel pressure.
Moreover, the fuel that returns from the engine heats the fuel inside the tank and leads to fuel evaporation.
This issue is addressed with the fuel pump control module with the return-less fuel system.
The fuel pressure sensor is typically fitted in the fuel delivery line and gives input to the engine control module regarding the fuel pressure.
Based on the fuel pressure sensor input against desired fuel pressure in the fuel delivery system, a signal is sent from the engine control module to the fuel pump control module to adjust the fuel pump speed.
The fuel pump control module also sends a feedback signal to the PCM for diagnostic information.
The fuel pump control module sends PWM (Pulse width modulation) signals to the fuel pump to adjust the speed of the fuel pump by changing the signal duty cycle.
Any change in fuel pump speed affects the fuel pump volume flow rate and fuel pressure.
The fuel pump control module typically performs fine without any issue but when it is subjected to moisture or high temperature, it may develop corrosion and may malfunction, especially when the aluminum body of the fuel pump control module comes in contact with the vehicle’s steel body which typically causes galvanic corrosion because of the dissimilar metals coming in contact with each other.
How To Do Silverado Fuel Pump Control Module Bypass?
If your GM Silverado is not starting, then the first and foremost thing that one would doubt is the proper running of the fuel pump.
The fuel pump is like the heart of the engine which supplies fuel to the engine for its operation.
Any malfunction in the fuel pump delivery or pressure would make your vehicle hesitate or misfire and ultimately the vehicle ends up having starting problems.
It is not a fuel pump alone which ensures fuel delivery but there are many other components in the series like the fuel pump control module and fuel pump relay which are involved in ensuring the desired function of the fuel pump.
Any malfunction in the fuel pump relay or fuel pump control module leads to a similar issue as if your fuel pump is not functioning as per intent.
If your car won’t start even after the fuel pump replacement, then you need to diagnose or bypass either the fuel pump control module or fuel pump relay to troubleshoot the problem.
If the fuel pump is not getting power, then other than the fuel pump relay, you need to check the fuel pump control module which finally controls the fuel pump and its pressure.
The fuel pump control module bypass is typically done to confirm whether the pump is working fine or not.
If you have already tried bypassing the fuel pump relay and even after that if the pump is not working, then the fuel pump control module bypass in your Silverado is the next thing that you should try to troubleshoot the fuel pump.
The fuel pump usually gets the power supply from the hot-wired battery after satisfying certain predefined circuit logic and the power has to cross a sequence of components in the circuit.
The circuit starts from the battery, fuse, ignition switch, ECM main relay, ECM, fuel pump relay, and fuel pump control module and finally, the power reaches the fuel pump for its operation.
The fuel pump control module has four pins (16, 1, 32, and 47). Pin 16 is connected to red-white stripped wire sometimes grey as well and it is the hot-wired battery source.
Typically, a black or pink colored wire is connected to pin 1 which serves the function of ground.
If you connect the tester to battery +ve and connect the tester to pin 1 then the tester should glow indicating good ground availability.
Usually, a red or green wire is connected to pin 32 which represents power coming into the fuel pump control module through the engine control module or from the fuel pump relay.
The pin 47 in the fuel pump control module is fuel pump positive.
The pins 16 and 1 form a pair. Similarly, pins 32 and 47 form another pair.
The below steps will help you understand how to bypass fuel pump control module in Silverado.
- First, locate the fuel pump control module which typically is placed over the spare wheel in between the front and rear wheels in Silverado.
- Pull the tab on the connector of the fuel pump control module to one side and unplug it. You may see several ports on the connector and details of which port goes to which parts shall be written in the owner’s manual.
- Use a copper wire of sufficient length to connect the required ports. Strip off some portion of protective insulation over the ends of the copper wire before connecting it to the connector ports.
- For bypassing the fuel pump control module, jump the connector ports corresponding to pin 16 and 1 on the fuel pump control module. Similarly, jump the ports corresponding to pins 32 and 47 on the fuel pump control module. By doing this you are directly hot-wiring the fuel pump to the battery.
- Once the copper wires are connected and the desired ports are jumped, you may hear the fuel pump humming sound coming from underneath your vehicle.
- By doing this you would bypass the signals from the fuel pump control module to the fuel pump and provide continuous power supply to the fuel pump directly from the battery source.
By bypassing the fuel pump control module in Silverado, irrespective of the ignition switch position or ECM signals to the fuel pump control module and fuel pump relay, the fuel pump will constantly receive the battery voltage and run continuously ON.
If the fuel pump doesn’t run even after the Silverado fuel pump control module bypass, then either the fuel pump or the engine PCM may be faulty.
Is It Safe To Bypass Fuel Pump Control Module?
Can you run a fuel pump without a fuel pump control module? Yes, you can run the pump.
Can I wire my fuel pump straight to the battery? Yes, it can be done but as a temporary arrangement.
Bypassing the fuel pump control module in Silverado is advised as a short-term countermeasure but it is not a permanent solution as it would prove expensive at a later stage if left bypassed for a longer duration.
The above questions are the ones that people frequently ask to confirm whether is it safe to bypass the fuel pump control module. You will get your doubts cleared after going through the below points.
The Silverado fuel pump control module bypass is fine as a temporary fix, but as a permanent solution, it is wise to replace the fuel pump control module with a new one as early as possible.
Otherwise, you would encounter the effects of bypassing the fuel pump control module later as mentioned below.
Battery drain
Once you bypass the fuel pump control module, the fuel pump will run continuously with key on, hence there is a chance of the battery getting drained off completely.
Your vehicle may not start the next time when you start. You may need to remove battery terminals to switch off the fuel pump which may be a tedious task to do every time.
Noisy fuel pump
If your car ignition key is in the ON position, you may be able to hear a continuous humming sound from inside your vehicle even if it is in a parked condition which may tend to irritate you
Malfunctioning safety feature
Some safety features like inertia switches which tend to switch off the fuel pump in case of accident will not function as intended due to fuel pump control module bypass.
Hence it is not wise to consider Silverado fuel pump control module bypass as a permanent solution as it may lead to possible fire hazard situations during an emergency.
Reduced fuel pump durability
Since the fuel pump will keep on running continuously, the fuel pump’s durability life in terms of several hours will be reduced drastically and would fail early which no one would like, since the fuel pump replacements come at some cost.
Engine misfire
If you bypass the Silverado fuel pump control module, the vehicle will not run properly at 3/4 to full throttle position as the fuel pump gets the input from the fuel pump control module for controlling its speed and hence the discharge, flow rate, and pressure.
The fuel pump control module modulates pump voltage to be more efficient.
Final Thoughts
If you are stuck in the middle of the road and want to start your vehicle and drive up to the garage or auto shop, then bypassing the fuel pump control module would be the only option available to you as a temporary countermeasure to keep your car running.
Bypassing the fuel pump control module in Silverado is advised as a short-term countermeasure but it is not a permanent solution as it would prove expensive at a later stage if left bypassed for a longer duration.
Even after bypassing Silverado’s fuel pump control module, if the fuel pump doesn’t run, then there would be likely an issue with either the engine PCM or the fuel pump itself.
Happy Motoring!
References
https://www.silveradosierra.com/threads/bypass-fscm-bad-for-fuel-pump.433945/
https://www.gmt400.com/threads/seeking-88-98-hot-fuel-module-fuel-pump-driver-answers.57613/
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