Go Back   F150online Forums > Body > Electrical Systems
Sign in using an external account
Register Forgot Password?
Register Photos Vin Decoder FAQ Members Search Today's Posts Mark Forums Read Vendor DirectoryGarage

Electrical Systems SPONSORED BY:

Welcome to F150Online Forums!
Welcome to F150Online.com.

You are currently viewing our forums as a guest, which gives you limited access to view most discussions and access our other features. By joining our community you will have access to post topics, communicate privately with other members (PM), respond to polls, upload content and access many other special features. Registration is fast, simple and absolutely free so please, join the F150Online Forums community today!





Reply
 
 
 
 
Thread Tools Search this Thread Display Modes
  #1  
Old 12-15-2006, 11:32 PM
IKE IKE is offline
Senior Member
Garage is empty, add now
 
Join Date: Nov 1999
Location: St. Louis, MO -USA
Vehicle: 2004 FORD Ranger
Posts: 142
Send a message via Yahoo to IKE
Question no brake lights -2001 F150

A friend has a 2001 F150 which has developed a troublesome problem. When you turn on the parking/headlamps, the brake lights (including the CHMSL) come on and remain on bright. If you hit the turn signal or 4 ways, the indicator(s) in the cluster light steadily and the front corner lamps go to full brightness with no blinking...

We checked all fuses, they are all fine. Any ideas what could cause this and/or possible remedies?
Reply With Quote
  #2  
Old 12-16-2006, 02:01 AM
Technical Article Contributor
2006 Ford F-150
 
Join Date: Jun 2002
Location: Under the flightpath of ORD 22R
Vehicle: 2006 FORD F150
Posts: 10,240
Lets start with some specs on the truck.

1. Trim level & body style ( the wiring diagrams are a bit different for specific trim levels and body styles ), and if he has the factory trailer tow package, with all the relays installed.

2. If the main headlamp switch is in the off position :
2.1. Do the turn signals work correctly front and rear ?
2.2. Do the 3 brake lights ( without the turn signals on ) work correctly ?
2.3. Do the 3 brake lights ( with the turn signals on ) work correctly ?

3. With the problem noted, do the trailer tow wires exhibit the same symptoms as the truck ( both L and R S/T/x and the parking lamps.

4. What happend when you turn the main headlamp switch to on, and press on the brake lamps ( no change, or something different, note both front and rear ).

Those are the start to the questions that I can see.
Reply With Quote
  #3  
Old 12-16-2006, 08:11 AM
Senior Member
Garage is empty, add now
 
Join Date: Oct 2002
Location: St. Louis (Out in the woods)
Vehicle: 2001 Ford F250 6.8
Posts: 5,127
I'd suspect that your MFS has developed a short circuit, either internal or at the wiring harnes connector.

Steve
__________________
If your original owner's manual is missing, download a soft copy from www.fleet.ford.com under the MAINTENANCE tab.
1989 Taurus SHO What a project! Retired at 249K.
1997 Ford F150 SC 5.4L - Gone
1995 Mustang GT Convertible, only 68K miles.
1998 Ford Contour Wifey's old daily driver, now mine.
2001 F250 SD, 6.8L, 4 X4.
2007 Mercury Mariner AWD - Wifey's new daily driver
Reply With Quote
  #4  
Old 12-17-2006, 01:19 AM
IKE IKE is offline
Senior Member
Garage is empty, add now
 
Join Date: Nov 1999
Location: St. Louis, MO -USA
Vehicle: 2004 FORD Ranger
Posts: 142
Send a message via Yahoo to IKE
Quote:
Originally Posted by SSCULLY
Lets start with some specs on the truck.
EDIT: I got a reply, the answers are added below in bold.

1. XL Regular cab longbed, 4x2, 4.2 L auto. The truck had the flat 4 plug from the factory, but no receiver, so I'm guessing it doesn't have the tow package.

2.1. They work until the brake pedal is pressed, at which
time they just stay stuck on.

2.2. Not really, since they are on the whole time.

2.3. They are just on all the time if the light switch is on.


3. Have not checked, but will.

4. Brake lights are constantly lit when park/headlamp switch is on, although, if you press the pedal, there is a very slight increase in brightness.

Does "MFS" stand for "multi-function switch?"

Last edited by IKE; 12-17-2006 at 10:39 AM.
Reply With Quote
  #5  
Old 12-17-2006, 10:00 AM
Technical Article Contributor
2006 Ford F-150
 
Join Date: Jun 2002
Location: Under the flightpath of ORD 22R
Vehicle: 2006 FORD F150
Posts: 10,240
Quote:
Originally Posted by IKE
...<snip>...Does "MFS" stand for "multi-function switch?"
Yes, that is correct. Usually the Hazzard switch cleans the contacts / acts normal when used, this is why I was thinking along the lines of something could be shorted, but Steve has a point with that post.

If you want to short cut to testing the MFS, it can't hurt, and would be in the list of items, depending on the answers to the questions above.

If you want to go right to testing, remove the MFS from the steering wheel column. here is the procedure :
Click the image to open in full size.
Reply With Quote
  #6  
Old 12-17-2006, 10:45 AM
IKE IKE is offline
Senior Member
Garage is empty, add now
 
Join Date: Nov 1999
Location: St. Louis, MO -USA
Vehicle: 2004 FORD Ranger
Posts: 142
Send a message via Yahoo to IKE
I received a reply and added the answers above to keep them all in one place.

I did think of something else, there was an issue with the trailer wiring under the bed a while back necessitating a repair, could something screwed up back there cause symptoms such as this? Is there a way to isolate that harness?
__________________

-IKE

2004 Ford Ranger XL



------------------

Last edited by IKE; 12-18-2006 at 04:18 PM.
Reply With Quote
  #7  
Old 12-18-2006, 01:29 AM
Technical Article Contributor
2006 Ford F-150
 
Join Date: Jun 2002
Location: Under the flightpath of ORD 22R
Vehicle: 2006 FORD F150
Posts: 10,240
Well that is some good detail.

Not withstanding Steve's recomendation to test the MFS, I woudl take a slightly different approach.

Remove both rear bulbs, and see if the CHMSL still has the same problem, and check if with the parking lamps on, that the fronts are on the low element, and if you use the turn signals, or 4 Way, that th efront flash ( albeit quickly due to limited load ).

With the slightly brighter, I am guessing at a bad ground on the rear of the truck, and the stop lamp is where it is deriving ground from ( via the CHMSL or BOO switch ).

Removing both the rear bulbs will stop any ground finding.

Question on the flat 4 under the rear bumper, is this part of the factory system, or an add on kit, or DIY add on ?
Trying to figure out if it is using the trailer tow circuits in the truck, or the actual truck lights ( should not be ).
Reply With Quote
  #8  
Old 12-18-2006, 04:06 PM
IKE IKE is offline
Senior Member
Garage is empty, add now
 
Join Date: Nov 1999
Location: St. Louis, MO -USA
Vehicle: 2004 FORD Ranger
Posts: 142
Send a message via Yahoo to IKE
Quote:
Originally Posted by SSCULLY
Question on the flat 4 under the rear bumper, is this part of the factory system, or an add on kit, or DIY add on ?
Trying to figure out if it is using the trailer tow circuits in the truck, or the actual truck lights ( should not be ).
It is the factory wiring, but a new plug was spliced on during a repair...

I'll pass on the results of the bulb removal and see where that takes us.

Thanks!
__________________

-IKE

2004 Ford Ranger XL



------------------

Last edited by IKE; 12-18-2006 at 04:12 PM.
Reply With Quote
  #9  
Old 12-18-2006, 05:50 PM
Technical Article Contributor
2006 Ford F-150
 
Join Date: Jun 2002
Location: Under the flightpath of ORD 22R
Vehicle: 2006 FORD F150
Posts: 10,240
Quote:
Originally Posted by IKE
It is the factory wiring, but a new plug was spliced on during a repair...

I'll pass on the results of the bulb removal and see where that takes us.

Thanks!
If it is the factory harness, unless he cut the ground side, it should not be a problem. The ground splice is to the frame where the factory tow harness connector is at. You can see it just below the connector for the factory 7&4 pin harness, it is a screw into the frame with a 10 AWG white wire I do believe.
Click the image to open in full size.
Reply With Quote
  #10  
Old 12-18-2006, 06:44 PM
IKE IKE is offline
Senior Member
Garage is empty, add now
 
Join Date: Nov 1999
Location: St. Louis, MO -USA
Vehicle: 2004 FORD Ranger
Posts: 142
Send a message via Yahoo to IKE
Well, that very well could be the issue, there was a ground problem with the 4 pin (which is all the truck has, no 7 pin connector) and a new plug was spliced in with a new ground. Is the lead to the 4 pin a seperate harness, ie, is there a point where that can be unplugged to isolate it? (I don't recall and the truck isn't here to look at)
__________________

-IKE

2004 Ford Ranger XL



------------------
Reply With Quote
  #11  
Old 12-18-2006, 07:22 PM
Technical Article Contributor
2006 Ford F-150
 
Join Date: Jun 2002
Location: Under the flightpath of ORD 22R
Vehicle: 2006 FORD F150
Posts: 10,240
Quote:
Originally Posted by IKE
Well, that very well could be the issue, there was a ground problem with the 4 pin (which is all the truck has, no 7 pin connector) and a new plug was spliced in with a new ground. Is the lead to the 4 pin a seperate harness, ie, is there a point where that can be unplugged to isolate it? (I don't recall and the truck isn't here to look at)
I think it is the same connector up under the truck.

On my '01 and my '06 it was easier to see by dropping the spare tire.

Take a bulb out of one of the S/T/T and check the ground to the frame ( clean bolt ) as a starting point. Should be 0 ohms or the continuity tone.
Reply With Quote
  #12  
Old 12-20-2006, 12:01 AM
IKE IKE is offline
Senior Member
Garage is empty, add now
 
Join Date: Nov 1999
Location: St. Louis, MO -USA
Vehicle: 2004 FORD Ranger
Posts: 142
Send a message via Yahoo to IKE
SSCULLY: Thanks for the help, we traced the problem to the plug. For now it has been clipped off and will be replaced at a later date. All lights now work properly.

Thanks again!
__________________

-IKE

2004 Ford Ranger XL



------------------
Reply With Quote
  #13  
Old 12-20-2006, 10:48 AM
Technical Article Contributor
2006 Ford F-150
 
Join Date: Jun 2002
Location: Under the flightpath of ORD 22R
Vehicle: 2006 FORD F150
Posts: 10,240
Quote:
Originally Posted by IKE
SSCULLY: Thanks for the help, we traced the problem to the plug. For now it has been clipped off and will be replaced at a later date. All lights now work properly.

Thanks again!
Don't thank me, I had you going upstream. You guys got that one on your own !
Thank yourselves for problem diagnoses 101, completed sucessfully !
Reply With Quote
Old 12-20-2006, 10:48 AM


 
 
 
Reply

Thread Tools Search this Thread
Search this Thread:

Advanced Search
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are On
Refbacks are Off


All times are GMT -4. The time now is 05:51 AM.


 
This forum is owned and operated by Internet Brands, Inc., a Delaware corporation. It is not authorized or endorsed by the Ford Motor Company and is not affiliated with the Ford Motor Company or its related companies in any way. FordŽ is a registered trademark of the Ford Motor Company
Contact Us Advertising Privacy Statement Terms of Service Jobs Forum Text Archives
Emails & Contact Details

Search Engine Friendly URLs by vBSEO 3.5.2