Wrench Light on Ford F-150! It’s Serious

Mostly, a wrench light means there’s an internal issue that needs servicing. The wrench light on Ford F-150 could be a sign of a PCM (Powertrain Control Module) or AWD, 4WD malfunction. This might happen because of a throttle problem, low voltage, or even a spark plug. Also, this leads to no acceleration.

As you’re driving your Ford F-150 truck, you might see a yellow light. It’s indicating that it’s time for servicing the truck. Well, you need to respond to that ASAP or it might get worse. 

Don’t be worried. Keep on reading. Here, I will guide you regarding what the wrench light on Ford F-150 means, why it shows, and how to fix the issue. 

Wrench Light on Ford F-150: Symptoms and Solutions

One of the most common reasons for a wrench light on Ford F-150 is that your truck needs an oil change. It is better to change the oil every three months for smooth performance. So, let’s see what are symptoms and solutions to the problem. 

Reasons	Symptoms	Solutions
Powertrain Control Module (PCM) issues	Engine is stalling. Engine is Misfiring, Engine is failing to start Poor fuel economy	Check wiring and connectors, fix or replace accordingly.Check for water damage. Replace the PCM if required.
Transmission system problem	Engine won’t start or make noises.Gears slipping.Fuel leaks or fuel burn. Low transmission fluid level.Heating of the transmission system.	Check and fix the transmission control module.Transmission fluid must be refilled or replaced.
Battery issues	Low voltage.Drained-out battery.	Charge the batteryRejuvenate the battery.Replace the battery
Throttle Body and Throttle Position Sensor(TPS)	Engine is forced idling. Throttle valve is not responding. Truck is completely shut down.	The TSP needs to be located.Use a multimeter to check the TSP.Replace it if required.
Electronic Throttle Body (ETB)	Sudden loss of power.	Run the OBD scanner for error codes.The ETB needs to be cleaned without removing it. Then the error code must be reset.If not working, remove & replace.
4-Wheel-Drive/All-Wheel-Drive Malfunction	Truck gets stuck in its place Truck goes limp mode.	Inspect the module for blown-out fuses or damaged wires.Scan for error codes. Diagnose it from a car mechanic.
Body control module malfunction	PCM okay, no diagnostic trouble codes, but the wrench light persists. Moisture problem.	Read the error codes using the OBD scanner.Inspect the wires on the BCM.

Reason 1. Powertrain Control Module (PCM) Issues

PCM issues are one of the common reasons behind the wrench light coming on your Ford F-150. You’ll be faced with engine misfiring, stalling, and reduced gas mileage. There could be broken or insulated wires, faulty connectors, broken connector blades, or bent pins. 

Additionally, water damage can cause PCM issues and trigger the wrench light. If water or moisture enters the PCM, there will be short circuits, corrosion, and rust. Let’s find out how to solve this. 

Solution 1

First, check the PCM for any possible short circuits. You also may find wirings and connectors are not properly insulated or broken. Try the following steps for a quick fix.   

Step 1: Identify the damaged or short-circuited wiring points and clean them. 

Step 2: Now, coat the damaged wiring with Crazy Glue or liquid electrical tape. 

Step 3: After that, let it dry for a bit. After it dried up, rewrap it with common electric tape.  

Solution 2   

Now, if there is thermal stress and vibrations, then the PCM’s circuit board will get microcracks leading to wiring track damage. Use an OBD scanner to find any error with the PCM. Let’s see now how to use the OBD scanner for finding error codes. 

Step 1: First, the diagnostic link connector (DLC) or the OBD port needs to be located. It is usually placed underneath and to the left of your truck’s steering column. On some F-150 trucks, the port/connector is a bit far so you may need to crouch down.   

Step 2: Connect the scanner to the port/DLC. 

Step 3: Turn the engine on and take a DTC (Diagnostic Trouble Code) scan. 

Step 4: If the scan shows the codes- P0606, P0603, P0601, etc, then you have a PCM-related issue, it may not be PCM itself but surely a component related to PCM. Any code starting with P06 indicates the condition of the PCM. 

Watch this video to learn how to use the OBD scanner. 

So, if OBD scanners showed you the error codes and you need to replace the PCM. It may cost you $800-1500$ for the replacement including labor costs. 

Here’s how to replace the powertrain control module on Ford F-150.

Tools 

1. Screwdriver
2. Wrench
3. Sockets
4. New power control module. 

[Precaution: Make sure to turn off the power.]

Step 1: Disconnect the battery by pulling up only the negative(black) cable.

Step 2: Locate the PCM and record the number written within. 

Step 3: Research the PCM number by vehicle model, year, drivetrain and engine components. This will ensure that you bought the right PCM for your vehicle. 

Step 4: Unclip and remove the old PCM gently and install the new PCM. 

Step 5: The battery is to be reconnected now. Then, turn on the engine. 

So, that’s it. Now, if you’re confused with the procedure, here’s a visual assistance for you. 

Reason 2. Transmission System Problem

A problem with your truck’s transmission system can also turn the wrench light on. 

Your F-150’s all electronic control modules are interlinked. As a result, a problem in one system gets to another. 

The engine is not starting or making noises, gears slipping, fuel leaking, or burning, low transmission fluid level, heating of the transmission system, etc are the common symptoms. 

The powertrain of the engine entails important parts such as the engine, driveshaft, and transmission. When something goes wrong in the PCM or ECM, the transmission gets affected and the wrench light comes on your Ford F-150. 

Solution

The solution to this problem is replacing or refilling the transmission fluid. But be sure to analyze the dipstick under the pickup’s hood to be sure if your transmission needs new fluid. Here’s how to change the transmission fluid on a Ford F-150.

Tools Needed

1. 5-6 quarts of new transmission fluid (Mercon V etc.) 
2. A new transmission filter
3. A ratchet
4. A funnel
5. A screwdriver
6. A large pan(equal to or greater than 15 quarts)
7. A 10 mm socket

Precautions

1. Wear protective gear(gloves, work glasses, etc.)
2. Turn the engine off and park in a safe and flat location. 

Step 1: Check the transmission fluid to confirm it needs replacement. If there’s difficulty or grinding noise in shifting gears, slipping gears, or even unexpected backward or forward surging, the transmission fluid must be changed. Usually, it’s better to change the transmission fluid after every 30-60 thousand miles drive.  

Step 2: Drain the existing fluid into the 15 quarts pan from the transmission pan.

Step 3: Remove the transmission filter by shimmying it down and out altogether. The O-ring also must be removed. Be careful not to touch the main control bore. Use a screwdriver for extra safe removal.  

To remove the filter, unscrew the 19mm bolt near the fill plug and dipstick. Then, unscrew the 6 bolts from the rear of the transmission pan first. Then unscrew the bolts of the front. You can use aluminum foil under the transmission pan to avoid filling the fluid all over the ground.  

Step 4: Clean the transmission pan. 

Step 5: Now, install the new filter. Bolt the transmission pan carefully.

Step 6: Pop the hood up. Then, carefully remove the transmission fluid dipstick. Using the funnel, distribute 5-6 quarts of new transmission fluid. 

Step 7: Heat up the transmission up to operating temperature(150°) by running the truck engine until it warms up. The information display will show you the transmission temperature. 

This process is not as easy as changing motor oil. So be careful and consult car mechanics if you do not have the expertise. If the steps get too confusing, here’s a video you can watch. 

Reason 3. Battery Issues

If the battery issue hits the engine, the warning light will start to blink continuously. This is a sign you cannot ignore as the engine will not start. You’ll be faced with low battery voltage or a drained-out battery. Don’t worry. There are remedies. 

Solution 1

First, it might be a simple low-charge problem. In that case, charge the battery properly. But if not, another safe and effective method is to rejuvenate the battery. A lead-acid battery will work fine in this procedure. You can rejuvenate the battery by applying acid. Let’s see how. 

Precautions: Proceed with extreme caution as you’ll be working with toxic car battery acid. Use acid only when the battery’s acid is spilled out. Also, wear protective gloves and goggles. 

Tools: You’ll just need distilled water and sulfuric acid.

Step 1: Measure the battery voltage. If the battery is totally gone, there will be minimal voltage. 

Step 2: Pour the distilled water into the battery to top it off. That should activate the battery acid. Voltage should increase by now. 

Step 3: If battery acid is spilled out, add the right amount of sulfuric acid. That should supplement the spilled-out acid.   

Step 4: Now, give the battery a kickstart to begin the charging process and the chemical reaction. If the battery does not come to life, apply the water and acid method a few more times. 

So, that should do the trick. If not, then the battery is out of its lifespan. 

Solution 2

Then, replacing the battery might be the best option. Here’s how to replace the battery on Ford F-150.

Precaution: As always when working with batteries make sure you’re wearing protective gloves and safety glasses.

Tools Needed 

1. An open-end wrench
2. A socket wrench
3. A wire brush
4. Anti-corrosion washers  
5. Battery grease

Step 1: Remove the cables using an open-end wrench. Remove the negative cable of the battery first then the positive one. 

Step 2: At the base of the battery, there’s a rubber block holding the battery in place. Use a socket wrench with an extension to remove the bolt holding the block in place.

Step 3: Now, that the battery is free you can lift it out of the engine bay and set it aside. 

Step 4: Before installing the new battery, clean both the positive and negative cable terminals with a wire brush. That’ll get rid of any corrosion and ensure a good connection with your new battery. 

Step 5: Put the new battery in place. Ensure that the positive and negative terminals on the battery are on the same side as the corresponding battery cables. The positive side corresponds to the red cable and the negative side to the black cable. 

Step 6: With the battery in place, reinstall the rubber hold down. Block, install, and tighten the bolt back on the top side of the battery.

Remove the red plastic protective cap from the positive terminal and install the anti-corrosion washers. Green for negative and red for positive. 

Step 7: Then apply a thin film of battery grease to each terminal. The new washers and the grease will help eliminate corrosion and ensure the maximum life for your new battery. 

Step 8: Now, connect the positive battery cable to the positive battery terminal and tighten it snuggly. Don’t over-tighten the battery terminals, but you also don’t want any wiggle in the connection at all. Similarly, do this for the negative cable. 

Step 9: Once all the connections are made and tightened, apply another thin coat of

battery terminal grease over the connections. Now get in the driver’s seat and start the vehicle and enjoy that quick starting new battery.

Here’s a visual guide for the whole process.

Reason 4. Throttle Body and Throttle Position Sensor (TPS) Issues

A faulty sensor, dirt or debris, or even a short circuit within the sensor’s wiring can cause this issue. Solutions to the Throttle Body and TPS problem are provided here.  

Solution 1

For dirt and debris on the throttle position sensor, try to clean the throttle body with spray cleaners like WD-40 or seafoam. The cleaning process is not a DIY project you should take. But for your convenience, I’ve made it easy with some steps. 

Here’s how to clean the throttle body on a Ford F-150. 

Tools Needed

1. Screwdrivers
2. Cleaning brush/toothbrush
3. Flashlight
4. Eye Protection
5. Throttle body cleaner
6. Household oil
7. Cotton swabs
8. Paper towels
9. Rubber gloves

Now, follow the below steps in the correct order.

Step 1: Disconnect the ground terminal of the vehicle’s battery for safety purposes.

Step 2: Access the throttle body. 

Step 3: Remove the air duct attaching the throttle body. If you’re unable to do it, stop right there. Let a professional hand do the rest from here.  

Step 4: Expose the throttle body by removing enough air ducting.

Step 5: The throttle body cleaner needs to be sprayed inside the air duct. Ensure that the plastic thin nozzle does not fall into the throttle body opening. 

Step 6: Keep spraying until the body shows a clear metal view. Get a flashlight to get a look.  

Step 7: Spill a small drop of household oil onto the shaft of the throttle body. 

Step 8: Using paper towels, clean out any liquid or residue that spilled in the surrounding engine. 

Step 9: Now, re-install the throttle body ducts. 

Step 10: Reconnect the battery. Turn on the engine and let it idle. To test, drive around the block. 

Here’s how it gets done if you’re still confused. 

Solution 2

Now, for a faulty sensor or short circuit, you might need to replace the throttle body. Let’s see how to replace the throttle position sensor on Ford F-150. 

Tools Needed

1. A hammer
2. A thread sealant
3. A screwdriver
4. A socket 
5. A ratchet (10mm)
6. New throttle position sensor.

Step 1: Start by removing the throttle body cover. To remove it, unscrew the 3 10mm bolts with a socket ratchet. Then remove the throttle body sensor which is located at the mantle fold’s front. Then use a screwdriver and a tabbing of the hammer to detach the accelerator cable. 

Source: ford-trucks.

Step 2: The negative cable of the battery needs to be disconnected. The location of TSP is near the driver’s position on the throttle body and connected by 2 10mm bolts. Unscrew the bolts to access the throttle body.  

Step 3: Then, the wiring harness connector should be removed from the throttle body sensor. Unscrew the two bolts that connect them.  

Step 4: Remove the vacuum hose. You can do this by simply twisting the hose clockwise or anti-clockwise. Then hold both opposite sides tightly and pull to remove it. Use a knife if it gets difficult to remove. 

Source: ford-trucks.

Step 5: Unscrew the mounting bolt. There are two of these and tightly connected to the TPS. Use the screwdriver and twist the bolt clockwise and tap it with the hammer to unfix it from the TPS. 

Step 6: Remove the existing TSP after unscrewing the mounting bolts. Get a new TSP with the exact size for smooth positioning.  

Step 7: Now, install the new TSP. There are corresponding bolts with sizes from 10 to 15 mm, whichever matches get those ones. Mount the new TSP in its position, put back the bolts and screws in their places, and tighten them with a ratchet. 

Step 8: Install the electrical connectors in their position as you removed them. Reconnect the negative battery terminal. 

Step 9: Re-install the parts as were removed. Finally, put back the ISA hose, duct system, and engine cover.    

For visual guidance on the replacement procedure, here’s something you can use. 

Reason 5. Electronic Throttle Body (ETB) Issue

A problem in ETB causes the warning light to come on. Accumulation of carbon or dirt restrains the throttle plate’s movement causing data misalignment within the ETB system. So what are the solutions to the ETB problem? Let’s see.  

Solutions

1. Remove the throttle body and clean it. 

2. Run the OBD scanner to find out the error code. If the scan shows the P0121, P2107, or P2112 codes, then you have a bad ETB condition and need to replace it.  

3. I’ll recommend replacing the ETB. It will cost you $100-$500 including all the parts involved. 

Let’s see how to replace the electronic throttle body on Ford F-150. 

Tools Needed

1. A ratchet
2. A 7mm socket
3. 8mm or 5/16s
4. A 10 mm socket
5. Plastic trim removal tool/Flat blade screwdriver
6. New throttle body and solid body gasket. 

Step 1: Use a 10mm socket for disconnecting the negative terminal on the battery. 

Step 2: Take a 7mm socket and remove the upper portion of the intake to access the throttle body. Remove the upper piece from over the throttle body.

Step 3: Remove the intake tube that the throttle body attaches to. Remove the 7mm hose clamps up top and then work your way down to the intercooler to loosen up those hose clamps as well.

Step 4: Remove the connector. There’s a little red tab. With a flat-blade screwdriver simply pull the tab out. Depress the Tang on the connector and pull it out of the throttle body. After that, simply remove the harness from the throttle body.

Step 5: Take an 8mm or 5/16 socket and remove all four bolts. Put the connector in and install the new electronic throttle body with a solid body gasket. 

Step 6: Now, turn the engine on and check the computer for codes. It should be cleared and that means the new ETB is installed properly. 

If that does not suffice your understanding, here’s a visual presentation of the process. 

Reason 6. AWD/4WD Malfunction

For trucks with 4WD, there’s a transfer case control module that allows shifting from 4WD to 2WD according to the truck’s speed. This is done by a shift relay and if it becomes faulty, the truck will go limp mode and the wrench light will come on. 

Now, let’s get to the solution part. 

Solution

Manually shifts from 4WD to 2WD so that you can drive to the nearest workshop for further diagnosis. The technician will diagnose and tell you the source of the problems. For AWD, replace all the tires if you can instead of mixing worn-out tires with new ones. 

If none of the solutions above work, check the module for any blown fuses or broken wires. Replace damaged wires accordingly and replace the module. Here’s how to do it.

Step 1: Disconnect the negative cable of the battery.

Step 2: Remove the electrical connection from the Transfer Case Control Module (TCCM) by sliding it towards the cluster while lifting the release tab up. Then, replace the TCCM with a new one.

This is a complicated process and it is recommended to see a technician for any AWD or 4WD issues. If not careful, you might damage the drive system. 

For a 2015 Ford F150, you can try resetting the TCCM by disconnecting the battery for 15 minutes.

Reason 7. Body Control Module Malfunction

Any problem with the body control module can ignite the wrench light. Moisture is a common problem for BCM. Also, problems with ETB or PCM lead to problems in BCM. If the PCM is not giving any problem codes then it might be the case of BCM. 

Solution

Step 1: Using OBD scanners, diagnose for error codes and resolve them. If the code U0140 comes up, then the BCM is bad as the engine loses communication with it. 

Step 2: Inspect the wires on the BCM and look for broken or damp wires. It is located beneath the dashboard of the driver’s side and towards the vehicle’s center. 

Step 3: For broken wires, connect them after cleaning them with Crazy Glue or liquid electrical tape. 

Usually, regularly cleaning the BCM helps to avoid any issues with it. But if damaged it can’t be repaired, you need to replace it. Many newer models of Ford F-150 have dedicated computers to synchronize it with the engine and electrical systems of the truck. To replace the BCM follow these steps. 

1. There are ducts, panels, and trim covers that need to be removed to access the BCM. 
2. The wiring harness plug within the BCM needs to be disconnected. 
3. Unfix the BCM from its mounted position by unscrewing the bolts.
4. Remove the BCM and position the new one in its place. 
5. Reconnect the screws to mount the new BCM and also re-attach the wiring harness.   
6. Re-install the ducts, trim covers, and panels.
7. Use an OBD Scanner to program the new BCM’s compatibility with your truck. 
8. Drive the truck and test if everything works perfectly. If the wrench light does not come on and if the BCM is communicating correctly, the replacement is successful.  

How to Temporarily Resolve Wrench Light on Ford F-150

For emergency situations, there are ways you can temporarily resolve the wrench light problem on your Ford F-150. 

But remember, doing this is not recommended. Only when you’re stranded somewhere or on a long drive. And only apply these temporary resolutions when in emergency situations. 

First, Turn off the truck, open and close the door, and turn the truck on again. It should reset the system. 

Secondly, the negative battery terminal needs to be disconnected. After 10-15 minutes, reconnect the battery. This will reset the control modules by draining their power. 

Thirdly, you can use FORScan to clear away the error codes from the PCM. 

Again, it is strongly advised that do not stay idle when the wrench light comes on your Ford F-150. You should get to repair or maintenance or it will be more haphazard later.  

Can You Drive With Wrench Light on Ford F-150?

Yes, you can drive with the wrench light on, but for a shorter period to get it diagnosed. It is strongly advised that you do not take the warning yellow light idly and drive for long. The breaks may not work properly after some time as the PCM and battery go dark.

Also, the Ford F-150 will go into limp mode just when the yellow light comes on the dashboard. Thus, it reduces the power of the engine to safely take the truck for an oil change or mandatory diagnostic.    

FAQs

Does The Wrench Light Mean Oil Change?

Yes, the wrench light means an oil change if your vehicle needs one. Your vehicle needs an oil change after every three months. The light means that your oil level is low or you need a new oil filter.