[Solved] 2011 Ford F-250 - Blinkers do not work with new light bulbs

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As a mechanic, there are some vehicles that look normal on the outside but have a dark secret on the inside. This is one of those vehicles.

Customer Complaint:

The blinkers blink fast like a bulb is out, but new bulbs were installed.

First Thoughts:

The blinkers on these trucks are controlled by the Body Control Module (BCM) and when they detect a bulb is blown, it will set a code.

I have seen Ford blinkers still not work with new bulbs because the fault code has to be cleared before it will start working again.

Diagnostics:

The first step I wanted to take on this truck was to first verify the customer complaint then check to see if there were any codes in the BCM.

The picture above shows the codes that were in the BCM. The only ones I’m worried about are the “Turn Indicator” and “Turn Lamp” codes.

What stood out to me, was the codes say the circuit is short to ground.

What does short to ground mean?

Short to ground means that the wires to that component are possibly touching a ground.

This could mean:

1. The wire is touching the frame.

2. Bare wires are touching and one happens to be ground.

3. The component is internally shorted to ground.

Since the bulbs were replaced by someone else, I decided to clear the codes to see if the blinkers would start to work.

The left turn signal code came back after being cleared.

When the codes were cleared, the right side blinker started to work properly, but the left blinker worked for a second then stopped working. The code for the left blinker came back also.

At this point, I knew I had an actual short to ground on the left front blinker.

I decided to do a visual inspection next.

What I was looking for in my visual inspection was a:

1. Wire rubbing on the frame.

2. Some bare wires touching each other.

3. A bad bulb.

Even though the customer stated they replaced the bulb for the blinker, it’s always good practice to double-check.

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What I found next was a little shocking.

Household extension cord connected to the left front blinker

As you can see from the picture above, there is an extension cord wired into the left front blinker wires.

It never ceases to amaze me the contraptions I find in some of these vehicles.

It turns out that the owner of this vehicle wired extra lights in the rear of the truck.

I decided to trace the extension cord because I had a hunch that there is some exposed wire rubbing on the frame.

As expected, there was a pinched wire.

As you can see from the picture above, the customer installed extension cord that ran right next to worn-out body bushing.

These trucks are notorious for having worn-out body bushing.

What probably happened was the customer installed the extension cord near the body bushing and as the truck hit bumps in the road, the extension cord slowly moved in a spot where it would be pinched. This caused the wire to rub on the frame, aka shorting to ground.

The picture below is of the cord after I removed it from the body bushing.

After repairing the extension cord and placing it in a safer area, the truck’s blinkers worked correctly.

This truck is fixed!

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