Ford F-150 has an advanced warning system on its dashboard to alert the truck owners before any potential or severe malfunctioning of the engine.
Yellow wrench symbol is one such light to glow when a truck computer detects any abnormality in specific systems.
What Does the Wrench Light Mean on a Ford F150? In general, a Wrench light on the dash of the Ford F-150 means any problem in the powertrain control module or all-wheel-drive system. Other possible reasons can be problems with the electronic throttle body and its sensor. Malfunctioning of BCM or transmission systems can also sometimes result in wrench light appearing.
I have successfully diagnosed and resolved the Wrench light warning alert on my Ford F-150 by following the sequence of steps and checking components described in this article.
What Does the Wrench Light Mean on a Ford F150?
There are numerous underlying causes for wrench light to come on your Ford F-150 truck.
You should follow this step-by-step guide from visually inspecting the wiring and other safety parts to running Onboard Diagnostic Scanner (OBD) to get the error codes. It will help you to specify the faulty system.
Powertrain control module (PCM) malfunction
The most frequent reason I have found for wrench light to come on the dashboard of Ford F-150 is some problem with the PCM or ECM of the truck.
Therefore as a first step, check the PCM board for any short circuit due to water damage. Its exposure to water or moisture causes rusting of connector pins and short-circuiting of components.
Therefore, I regularly inspect this electronic board and dry it by blowing hot air to prevent moisturizing of electronic components.
Moreover, heating of the board and thermal vibrations can damage the wiring tracks on its PCB.
Therefore, that can be the reason behind the yellow wrench appearing on the dashboard. In that case, you need to replace the PCM with a new one.
If you find the condition of PCM is OK, the next step is to run the OBD tool to read error codes in the memory of the engine computer.
Error code will pinpoint the faulty part of the system. However, you may not get any error code in some cases, and the warning light is a false signal or glitch in the power system.
However, it is crucial to get your truck checked whenever the warning light comes on the board.
Check wiring and fuses
Next, you should visually inspect the wiring harnesses and fuses of the truck.
A loose connector or broken wire can result in a warning alert regarding that system.
Remove the connectors and clean them for any carbon deposition, corrosion, or dust accumulation. The grounding of a wire can also cause the wrench light to glow on the truck.
Throttle position sensor (TPS) problem
Possible forms of TPS malfunction are faulty sensor and shorting of its wiring. Its symptoms are the forced idling, unresponsive throttle valve, and complete shutdown of the truck.
Locate the sensor in the electronic throttle body, check it using a multimeter, and replace the throttle body position sensor to resolve the problem.
Check electronic throttle body
The electronic throttle body (ETB) in Ford F-150 serves to control air intake to the engine in response to the driver throttle pedal.
Its failure will result in the sudden loss of power and wrench sign light on the dashboard. Visit the nearest Ford dealer shop to run the ODB scanner for error codes.
It is also a frequent cause of the warning light to appear on the dashboard.
I recommend removing the throttle body, thoroughly cleaning it, and resetting the error code to check if it works.
However, you need to replace the entire electronic throttle body and its actuator to rectify the problem in extreme cases.
4-wheel drive module malfunction
Trucks with 4-wheel drive (4WD) options have a transfer case control module to switch between 2WD and 4WD according to the speed of the Ford F-150.
If the shift relay gets faulty, your truck will be stuck in its place, going to limp mode and the wrench light goes on.
Check the module for any broken wire or blown-out fuses. You can drive the truck by manually shifting to the 2WD option and visit the workshop to diagnose the problem according to the error codes.
Body control module malfunction
If the PCM of the truck does not give any diagnostic trouble codes and the wrench light persists, then you should check BCM.
Moisture on the module also can be a source of trouble sometimes. Use OBD to read error codes and resolve them. Moreover, also inspect the wires on the BCM specifically for the auto start-stop feature.
Transmission system problems
All the electronic control modules of the Ford F-150 have interlocks with each other. As a result, often, a problem in one system can indicate a fault in another system.
Therefore, besides diagnosing PCM and BCM for diagnostic trouble codes (DTCs), check the transmission control module.
Low transmission fluid level or heating of the transmission system can also cause the wrench light to turn ON. Replace or refill the transmission fluid to see if it resolves the problem.
Is the Wrench light the same as the Check engine light and oil change reminder light?
Yellow wrench light has a similar meaning as that of check engine light despite having different symbols.
Both indicate or warn of the malfunctioning of the ECU or PCM and overheating of the engine.
Moreover, they are the result of the same error codes. For example, the oil change reminder light has a wrench as its symbol. But it is different from the yellow warning light indicating a severe engine problem.
Therefore, you should not confuse them with each other because an oil change reminder light is not of extreme level and a reminder for an oil change.
Is it Ok to drive a truck with the Wrench light ON?
You can drive the truck with the powertrain malfunction light ON for shorter periods to get it checked.
However, avoid ignoring the warning lights if they don’t go away after resetting the truck.
Ford F-150 enters into limp mode as soon as the yellow light glows on the dashboard.
It reduces the engine power to ensure the truck’s safety while allowing its movement to visit the workshop.
It would be best to look for immediate repairs instead of driving to avoid further damage to the truck, resulting in costly maintenance.
How to temporarily resolve the wrench light issue on Ford F150?
There are quick tricks available to reset the error codes to force the yellow wrench symbol to go away in case of a false signal.
One such method is to turn OFF the truck for a few minutes and turn it ON. remove the light if it was a result of heating of the engine.
Another trick is to disconnect the battery’s negative terminal for 10-15 minutes and reconnect it to reset the control modules by draining its power.
You can also remove the error codes by clearing the PCM using FORScan. These methods will temporarily remove the warning light issue.
However, you must immediately seek help from the workshop or Ford dealers if the warning light persists even after resetting it.
Estimated repair cost to resolve the problem
The estimated repair cost to resolve the yellow wrench light on Ford F-150 can vary according to the error code and faulty part.
In PCM replacement, the cost involved can be in the range of $800-$1000, including labor cost.
Electronic throttle body repair or replacement cost can be $100-$500 according to the parts involved.
Repairing costs for other components can be in the range of $100-$300, mainly in repair and labor costs.