brake light fuse burns but blinkers work

[lillbro11]

88 f-150 4.9 My brake lights are blowing the fuse but the blinkers, hazards, and running lights are all fine. I'm figuring its a wire grounding out somewhere but I'm curious which wire it is. I know its a red wire with a white stripe coming out of the fuse box but which wire after that?

[wolfsmurf]

check your trailer plug in the back. most likely place to start.

[lillbro11]

I traced the red with white stripe and it runs across to the passenger side behind the glove box and into some flasher looking thing and it changes to green with red stripe and goes back to the brake sensor switch. when the brake is pushed the current goes through the switch and comes out into a solid green wire. now where does it go

[wolfsmurf]

check your trailer light plug in the back. most likely place to start.its prolly been pinched and run over and chewed by the dog.

[F150xlt]

Originally Posted by lillbro11

I traced the red with white stripe and it runs across to the passenger side behind the glove box and into some flasher looking thing and it changes to green with red stripe and goes back to the brake sensor switch. when the brake is pushed the current goes through the switch and comes out into a solid green wire. now where does it go

From Fuse #1 is a Red/White wire that goes to the Hazard flasher which should be located on the backside of the fuse panel. You say yours is behind the glove box area?

The Red/White wire at the Hazard flasher splices together to a Light Green/Red wire and goes to the input of the Brake light switch.

On the output side of the Brake light switch is a Light Green wire which turns into a splice with 3 Light Green wires. 1 wire goes to the turn signal switch, the second wire goes to the ABS module and the 3 wire goes to the Cruise Control amplifier.


ABS module is located behind instrument panel left of center.
Cruise control amplifier is located behind instrument panel at right hand side of steering column.

[lillbro11]

Well knowing that the turn signals, running lights, and hazards still work. Does that mean that the wires outside of the cab are fine. Because if the grounded spot was outside of the cab wouldn't it blow all the fuses that control rear light functions. If I'm wrong please let me know. I'm currently in the truck and responding to this on my phone so answers sooner helps. Thanks for the responses so far and any future responses

[F150xlt]

The wiring must be good up to the out put of the turn signal switch since the blinkers work.

Blinkers and Brake lights use the same bulb filament.

It indicates the problem could be.

1) The turn signal/hazard switch
2) Wiring from the brake switch to the turn signal switch
3) Wiring to the ABS module
4) Wiring to the Cruise Control amplifier
5) Or bad Cruise Control amplifier or bad ABS module

At the base of the steering column is a Gray 11 pin connector that comes from the turn signal/hazard switch if you unplug that connector and step on the brake pedal, and the fuse doesn't blow, that would indicate something is wrong with the turn signal switch.

If the fuse still blows something is wrong with the wiring to the ABS module or Cruise Control amp., wiring from brake switch to the turn signal switch connector or either module could be bad.

You'd have to disconnect the wire at each module to determine where the problem is.

[ole_smokey_88]

I know this sounds like a pain but take your steering wheel off and check in around the turn signal cam i had the same problem with my 89 and there was a wire shorted out

[lillbro11]

I took the steering wheel off a week ago and changed the tilt adjuster lock thingy and thats when this all started. I took the dash off tonight to check for grounded wires and no luck finding any. And thanks F150xlt for the easy way to diagnosis where its coming from

[lillbro11]

ok I changed the turn signal switch and no more blown fuses. Now the driver front running light turns on with the ignition and the hazards don't blink they stay solid when the switch is pulled. The left blinker stays solid when flipped on but the right works fine.
Please help I'm lost on this problem.

[F150xlt]

Originally Posted by lillbro11

ok I changed the turn signal switch and no more blown fuses. Now the driver front running light turns on with the ignition and the hazards don't blink they stay solid when the switch is pulled. The left blinker stays solid when flipped on but the right works fine.
Please help I'm lost on this problem.

So you installed a new turn signal switch?

Did you specify the switch was for a tilt steering wheel?

Did you poke the wires out of the grey connector to thread the wires down the column and then reinstall the wires in the gray connector?

Verify the Light Green/White wire is in the proper position on the connector.

Below is a picture of the Gray connector as you look at the connector head on.

Outside row connector pins from top to bottom

Black/Pink wire
LIght Green wire
Orange/Light Blue wire
LIght Green/Orange wire
White/Red wire
Yellow/Light Blue wire

Inside row connector pins from top to bottom

***Light Green/White wire *** This is the wire for the front driverside Blinker
White/Light Blue wire
Dark Blue wire
White Purple wire (May not have this wire).

The Hazards won't work unless all the blinker bulbs work because not enough current will be drawn for the hazard flasher to work.














'

[lillbro11]

I unplugged the gray connector for the turn signals and the left front light still stays on along with the left turn signal light inside the cab but it doesn't blink

[F150xlt]

With the gray connector disconnected, the circuit for the front driver side turn signal bulb and the turn signal indicator in the dash is open.

The Green/White wire is getting power from some where. The circuit should be dead.

Has the turn signals ever worked properly since you've owned the vehicle?

[lillbro11]

Thanks a lot F150xlt. It's fixed. Somehow it was getting power from the back of the gauge pod so i changed it and everythings good.

[F150xlt]

Good to hear.