I didn't find anything on this issue so thought I'd start one. I recieved the PO Code 0581 which is the cruise control circuit issue. I have an 07 F150 STX special.edition and my cruise controls are on the steering wheel. Could there be another cause for.this before I had e to start looking around in the steering wheel?

 

LED lights bulbs can cause this . It is very well known problem . I had to remove LED bulbs in my hot climate because of high failures. I like the light but not the high cost of frequent fails . After 300-400 bucks I went back to factory bulbs .
The most common cruise fail is an led light in third brake light .A bad bulb can also cause this .

 

You should probably look up the DTC before throwing something out there that's just going to waste time and possibly money.

 

No argument as I have no 1st hand. But I actually thought the problem LED lights caused was limited to failure of cruise to disengage when brake is pressed. ????

AGREED, and I DID. Maybe something here can avoid his wasting time and money.

Judging from the diagram in my Factory Electrical Service Manual (2005 but I can't imagine much differences in yours) - there are not too many possibilities. Perhaps the Brake Pedal Pressed circuit shorted might (outside this diagram - ie: @redfishtd's comments), but I think the DTC would be different if that were the cause.

With the DTC of P0581 "Cruise Control Multifunction Input 'A' Circuit High", it doesn't look likely it would be outside the steering wheel. I think the 'Multifunction input" is the resistance ladder between the individual switches - but IDK that. Anyhow, if the ground reference side is open ..... ????

I would think F1 in the Auxiliary Fuse Box would have to be GOOD for a DTC designated as malfunction "Input 'A' Circuit _HIGH_", as that seems the most likely source for supervisory voltage. But hopefully with the diagram and wire colors - (if they check out same as 2007) should help diagnose.

IF YOU (or other members) ARE, BY CHANCE, a Torque Pro (Android OBDII scanner app) user, you can create Custom PIDs and watch the individual buttons being pressed as the OBDII system sets and unsets flag 'bits' in the PCM's cruise control management routine. They SHOULD all be OFF normally and set "ON" to indicate their respective condition. They are flag BITS within a 'word' at PID # A211. The PIDs are non-standard and not included in standard code readers or scanners - but it can be added in Torque Pro.

Mode/PID... 22A211
Long Name . _Cruise Control Buttons READY
Short Name. _CBRDY
Min/Max.... 0/1
Units...... On/Off
Equation... Bit(B:3)
Header..... Auto

=====>>>>> ///// Remaining "Cruise Control" diagnostic # A211 PIDS are same, EXCEPT for} Long Name : Short Name : Equation, as follows:

_Brake Pressure Applied (Cruise Cancel) : _BBP1 : Bit(B:1)
_Cruise Control OFF button Pressed : _SCSOP : Bit(B:6)
_Cruise Control ON button pressed : _SCS1P : Bit(B:7)
_Cruise Control SET button pressed : _CCSET : Bit(A:5)
_Cruise Control COAST button pressed : _CCCOAST : Bit(A:6)
_cruise Control RESUME button pressed : _CCRSUME : Bit(A:7)

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

These PIDs should all be applicable to all (at least) 2004 - 2008 gen Ford PU's. There are some other cruise ones but I have not yet been able to unscramble (HACK) their meanings.

PS: EDIT: The above OBDII signals are 'Momentary' like the switches. Only 'True' while the button is pressed.

 

If the BOO signal is not allowed to be pulled "down" to a logic "LOW" as is done by the filaments of the incandescent bulb(s) in the CHMSL, the speed control will be inhibited from engaging as the PCM will interpret the effectively open circuit as a logic HIGH and will interpret that level as if the brake lights are ON.

It could be the steering wheel switches, the clock spring, the wiring harness between the clockspring and the PCM or the PCM itself. Pinpoint diagnostics would need to be done unless guessing is good enough.

F1 in the Aux Fuse Box #1 is only for the illumination of the switches in the steering wheel and is only hot when the cluster and panel illumination circuit is active. The PCM sources the voltage used for speed control function switch engagement detection.

The Torque Pro stuff is very cool!

 

INTERESTING. You just provided another clue ----. for me anyhow.

That is another OBDII PID that the OP could verify (before tearing into the steering wheel). The BOO Brake Pedal Pressed - switch input) signal is available at PID # 1101 Bit(A:1) I missed it focusing on the Cruise Control stuff. A Torque Pro PID can be added as:

Mode/PID... 221101
Long Name . _Brake Pedal Position
Short Name. _BPP .... or _BOO as desired
Min/Max.... 0/1
Units...... On/Off
Equation... Bit(A:1)
Header..... Auto

And according to documentation (2004 - 2008 at least) the BOO signal should be electrically available at the PCM plug "B" -13.

 

I did fire from the hip .I realize it could be many things . just threw some common things out there . Its not a problem I really like to get into . . As a first reply I try to get the ball going instead of dead space. If the guy hasn't messed with the bulbs and they are working no big deal . I usually investigate the codes but my interest is not on cruise . I feel its a luxury nice thing.
So kudos to you guys that delve into this deeper .My skin is not that thin .Good going .

 

Hey @redfishtd - I wasn't jumping you. Hell I still want that beer you owe me when you get to South Texas. I just (wrongly) """"THOUGHT"""" the only problem LED lights caused with cruise was that you would just keep crusin' when you tapped the brakes. It just so happened I had recently figured out some more PIDs - involving the subject matter.. I haven't done a Torque dashboard for Cruise Diagnostics (YET), but thought they sure could help the OP.

 

That doesn't match what I'm seeing in the EVTM. I'm seeing the BOO input at C175B Pin 46. Pin 13 on one of the connectors is a power input, the pin 13 on the other two connectors are not used.

I think that the PID you described as "_Brake Pressure Applied (Cruise Cancel) : _BBP1 : Bit(B:1)" is the input from the deacitvator switch (brake pressure switch) that comes into the PCM on C175B-47 and is labeled as "BPS" on the schematics. That's the redundant pressure switch that's supposed to open when there's enough fluid pressure and is supposed to be the backup to the BOO input in case there's a switch failure.

Based on both the definition of the DTC and going through its diagnostic procedure, the BOO signal is not a factor for this fault.

 

@projectSHO89 if ONLY you knew how easy it is to TOTALLY confuse me - you wouldn't do that ^^^^^^ !!!

Thanks for the correction - as I hate disseminating bum information. There's well enough of that around here without my help. I relied solely on the Diagnostic Reference Chart - _BUT_ it does list B001 at pin B-13 of C175B (The outboard PCM plug).

Ahhh - The diagnostic reference chart _ALSO_ lists BOO2 at B-46 of CB175 and I did not catch that. And my wiring schematic indicates pin 46 (designated as 'BRK PDK POS') routes directly to the 'NO' side of the Brake Pedal Switch -w- other side sourced directly from (hot all time) Fuse 2. (This leaves me with a little confusion regarding PID designations and acronyms.

There is another PID that works on my truck designated as BPP (designated on some documentation as Brake Pedal Pressed --- ??? dammit, acronyms are not standardized either. But it is at PID # 0906, Bit(A:1) and it does track my brake pedal on my truck.

I also have an OBDII PID for B002 also (but I did not list it because I have never been able to verify it on my truck).

I welcome your feedback. Every bit of knowledge I can squeeze outa' you guys never goes to waste. It goes into my active database to be put back out at the appropriate time. And I'd love yo sort more of this out but don't want to hijack the OP's thread.

NOW as for the OP's problem..........

I was just trying to verify that we were dealing with a 5.4L from other posts by the OP - and ran across this:

I think the OP damn well needs to do more diagnostics before pulling the steering wheel!