Hey guys, new to the forum. I have an '04 fx4, my reverse lights and parking sensors quit working, all fuses are are good, any suggestions?

 

How did you check the fuse ( and which fuse did you check should be #14 ) ?

Do you have a new body style 2004 or a 2004 Heritage / Lightning ( not sure I think the trim you have is only the new body style, cab could be either way ).

The DTR ( Digital Transmission Range ) Sensor is what is used as the "reverse" switch for the automatic transmission.

If the DTR is off, I would suspect that the start in park / neutral would also be off ( the alignment of the DTR ).

Did you check the reverse bulb connector to see if there is power there when the truck is in reverse ( make sure it is not a blown bulb ).

The Parking aid, did you check the fuse for this ? ( Fuse # 18 )

If fuse #14 is blown, the parking aid will not be triggered, but if the bulbs are out, the parking aid would still be triggered, but if fuse # 18 is bad, nothing will happen.

 

Thanks for the info, I will retrace my steps, I'm sure I did something wrong

 

Don't assume you did something wrong, but best to check the fuses with a meter while plugged into the fuse panel. Check with the meter to ground ( or test light ) to the pins on the back of the fuse.

Also, make sure of what you are calling fuse #14 and Fuse #18, it is easy to count wrong when laying on your side on the passenger side floor, I have done it myself.

 

Sorry, but 12v is NOT the place for a test light. If he applies a test light to the wrong circuit (i.e. airbag) it could set it off in his face.

 

I have seen this posted several times, how is this ?

It is a bulb ( or the newer ones I guess a LED - I have not seen a test light in 3 decades myself ) with a length of wire & clip on one end, and an ice pike on the other.

 

Ok, just to be clear on what I'm working with here. I have on '04 FX4, the reverse lights and parking sensors have quit working. I "checked" the fuses as in pulled them and looked at them, I then put the truck in reverse, pulled the bulb and used a test light at the connector, no fire. As far as the #18 fuse, I'm sure it is good as I dropped it the first time I pulled it out(it fell in that hole below the box), on the way to the store, I noticed that with that fuse out, my auto on headlights and turn signals did not work. I'm assuming from that, I must have something else going on. Ugh ironicly in the reflection of the store windows I noticed that the brake light above the rear window wasnt working...
perfect!

 

If you are just pulling and looking at the fuse, that is not checking / testing it, that is looking at it. Use a meter with it installed.

Until you know for sure there is power on both sides of the fuse, you are wasting your time checking the bulb connector.

Fuse #18, sounds like it was good, but that is one heck of a way to test it ( check your OM, the items you listed are part of it ).

If your other 2 stop lamps were working, the bulb is out on the CHMSL or there is an issue with the bulb connector. That circuit is the one prior to the MFS, for the 2 stop lamps on the bed of the truck. If it was a fuse or BPP ( Brake Pedal Position ) Switch, none of them would work.

 

A test light has to draw some current to light the bulb. Air bag circuits are a very delicate circuit, and even that small change in current can cause them to deploy.

Also, test lights are a horrible measure of voltage...they are very imprecise.

 

Ok so lets just say I'm not getting power at the fuse... what would be my next step, is there another relay/breaker or main fuse under the hood? Assuming that I have power at the fuse, I have a bad connection between it and the lights.

 

Rather then play the game of what if, just test both sides of the fuse, this is testing the fuse itself.

You are going beyond the 1st step at this point.

If you have power on 1 pin on the back of the fuse, and not the other, the fuse is bad replace it.

 

easier to just use a DMM to check continuity of the fuse. Theres two small metal spots on the top of the fuse. Set your DMM to continuity, and place one probe on each small metal spot. If your DMM beeps, your fuse is good.

 

How does a "current change" deploy an airbag ?
If this was the case, starting the truck could cause the airbags to deploy, as there is a "current change" in the electrical system when the truck starts.
Or take the case of pressing the up button on a power window when it is up, ever notice that the lights dim due to the draw on the motor when it is at full travel 1 direction ?

The SRS system is not armed until at 23.5 mph.
The 2001 is speed and deceleration that cause the airbags to deploy.
97-98 MY, there are front sensors, think the speed part might not be there ( never looked that close at the RCM to see ).
The 2004+ MY, there is speed ( 23.5 mph ) and impact severity to deploy the airbags ( slower speed impact, less force ), and the input of the seat position ( to know how close the occupant it for force ). The passenger seat, unless there is something like 60# in the seat, the airbag is not armed ( this is a sensor and a computer bag in the seat will illuminate the PAD ).

Actually a test light does not "measure" the voltage, it only shows if the system voltage is at a given point. If the system voltage is low, that is what it is showing. It will not point to a high resistance splice ( voltage drop ), but that is not what a test light was made to do.

This leaves out a few items for checking for power. Checking for continuity will not show if the fuse slot is stretched and not making contact.
Using the same pins on the back of the meter to check for power on both sides of the fuse will tell what is needed for the circuit, resistance will not.
Some meters to not have a sense of humor about checking continuity or resistance when the circuit is powered.