2005 Turn signals activate other lights code B1875

[MPGollotto]

OK I really am at a loss with this problem and looking for help anywhere. When selecting either right or left directional lights, all exterior lights come on, low beam headlights, driving lights both right and left, directional lamps both right and left , side marker lamps and even the license plate lamp. The Front Electronics Modules has been previously repaired and rechecked under the warranty, the Instrument cluster was sent in and supposedly repaired and verified in working order, the multifunction switch has been replaced, all in all no corrective action has fixed the problem. I am getting a B1875 failure code which say change the Hazard switch???

HELP!!!

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[biddle]

I've had this type of thing happen on my Jeep and disassemble the switch and cleaned all the contacts and it resolved it. Even the replacement could have issues with the contacts inside due to age. Look at my Jeep Multifunction switch inside:

Old Lincoln LS post from years ago-

The B1875 code points directly to a fault within the multi-function switch; it is not usually related to the light bulbs, but you should check your bulbs and housings. This code indicates that the switch is reading an invalid resistance value. The switch uses different resistors to signal turn direction, and the intermittent failure is likely caused by dirty or worn switch contacts. My own 2004 model experienced this issue, which occasionally caused erratic turn signal function before I got around to replacing the switch.

 

[doug7740]

The instrument cluster sends out a voltage reference signal through the white/violet wire to the multifunction switch. The return signal is carried through the brown/white wire, and shared with the high beam circuit, back to the instrument cluster. When the hazard switch is engaged, the voltage signal sent by the instrument cluster passes directly through the multifunction switch and returns to the instrument cluster.

The possible causes of fault code B1875 are:

• The multifunction switch
• The white/violet wire is shorted to ground
• The instrument cluster

doug7740
1955 Thunderbird Blue

 

[MPGollotto]

Thanks for the info, I believe I have a short somewhere since the Instrument cluster, FEM and multifunction switch have all been repaired / replaced. I am at my wits end but will tear into every plug and connector to see if anything looks like it can be causing the problem. Auto Ckt Solutions technicians seem to think I have a grounding problem somewhere but no help as to where.
Thanks again.

 

[biddle]

I believe

seem to think

When did you replaced your multi-function switch? Where did you get the part, was it new, used, aftermarket?

After you replaced your multi-function switch did you have EXACTLY the same issues, or were they slightly different?

PS why would you tear into every plug? Doug just told you which wire to check.

The possible causes of fault code B1875 are:

• The white/violet wire is shorted to ground

• 
  What microprocessor is it referring to that the white/violet wire goes to?
  
  

 

[MPGollotto]

I had a steering column from a 2003 I purchased for another reason and it had a good Multifunction switch on it. YES the same exact symptom appeared with both Multifunction switches. YES I am going to check the wires Doug told me to start with and then look for other plugs related to the Hazard Switch and directional lamps. I do appreciate your help.
MPG

Let me add something else to this POST, as we are sitting here in the house, the Horn on my TBIRD just started Blasting all by itself and I disconnected to fuse before my neighbor started complaining. Also I disconnected the plug going to the Multifunction switch and tried the headlight switch and observed all exterior lights are on including the direction lamps both right and left. Stating to look like a Christmas tree. I disconnected the battery for now until I can find what is going on. Maybe it's haunted!??

 

[biddle]

Let me add something else to this POST, as we are sitting here in the house, the Horn on my TBIRD just started Blasting all by itself and I disconnected to fuse before my neighbor started complaining.

What the manufacturing date on your battery sticker? You need to test the battery an eliminate it as the culprit. Bad batteries are often responsibly for these type of issues as well.

Here is a thread on the horn blowing- https://forums.fordthunderbirdforum.com/threads/2005-horn-wont-stop-blowing-after-wheel-tilt.9001/

If you reach a dead end, I suggest cleaning the contacts on the multifunction switch. Do you still have the old one, look at it and see if it looks like the photo above.

 

[MPGollotto]

Brand New Battery about 3 weeks old and fully charged the other day, I think I have a serious problem. Will keep digging at it. Also I have replaced a previously new battery for this one so no more batteries.