lsc8

Just wanted to post up my fix for others who are searching.

My 04 fx4, 5.4 would throw the cel, and wrench anytime you hit 40-45mph. It also had an abs light on. Most said to replace the tb and that the abs light would not be connected to the 2106 code. After cleaning old tb, maf, and then buying and installing a new one I had the same problem. Went buy a shop and had them scan the abs light(autozone and advanced couldn't pull it). Said the rear abs speed sensor was bad.

Replaced the rear abs speed sensor and now all lights are off and truck runs right.

I had found a few somewhat obscure references to this problem, which helped me. Hopefully this will help someone else.

Thanks guys!

04FX4SC

My truck is having the same problem, thank you for posting so that people don't think I'm crazy with thinking the 2 are related. I'll put in a new sensor and see if that fixes it. Question, did you have to disconnect the battery for it to relearn the new sensor?

techrep

iTrader: (1)

anytime you work on something electrical you should pull the cable on your battery.

lsc8

It should "see" that the new sensor is there and the abs light will go out as long as everything is corrected. You may have to drive a bit for it to pick up and correct itself in the computer. it will still have the codes stored in the computer if you scan it though even after the light is off. Which can be a little confusing.

iowagooser44

I have had the same problem for some time now. Replaced the rear speed sensor multiple times (defective), and still no fix. My ABS does not work now and I cant see paying the $100 fee from the dealership for something that I can fix. I even replaced a burned out 3rd brake light, heard that might be connected, with no results. Pretty frustrating though cant find the problem

04FX4SC

Where is the speed sensor located? I am having a shop pull the exact problem code and they seem annoyed I won't let them fix it. I replaced the TB already thinking that was it (long story why I replaced it) so I didn't want to "throw" anymore money at the problem, hence the shop visit.

lsc8

You may try taking the sensor out and cleaning the pumpkin where the sensor mounts very thoroughly with a scotch Brite and carb cleaner. It sounds dumb but it fixed my Superduty after a new sensor and wiring didn't. Plus it won't cost anything to try.

Have you had the code read? Is it going into limp mode?

lsc8

Speed sensor I replaced was in the pumpkin.

f150baller

Ive had this same problem for about 3 years now...2 sets of plugs and coil packs later engine sounds and idles better but cannot get it to come out of "limp home" mode. Just bought a new ABS module, TPS, and rear abs speed sensor. From my research ive narrowed it down to 1 of those 3...Mechanics always assume its the TB and it most cases it isn't. ABS system is known to cause the P2106 code. Ive also heard of some guys exhaust pipes burning through the wires that connect to your rear abs speed sensor on top of your rear differential.I had a code for a front wheel speed sensor also that I replaced and turned my wrench light off for a little while then it came back. Couple other cases have been IWE solenoid and fuel pump module which I replaced and didnt fix a thing. Sorry if this is info you already know, Ive just been dumping money into this issue forever.

iowagooser44

Had the code read.... thats what told me it was the rear speed sensor. No limp mode just light and no ABS