Evening all. I have an E350 V10 that started to be intermittent in setting the cruise control (it is factory, not aftermarket) and has now quit completely. Here are the things I have tried and the things I have checked thus far to no avail:

- Horn works
- All fuses good
- Cruise buttons light up
- Brake lights are all right
- Brakes work
- Took horn/airbag off and removed buttons and cleaned them with electronics cleaner (they were immaculate anyways)
- mashed on the buttons and wiggled the steering wheel while driving

I am considering tearing into the throttle body tomorrow to see if the cable came disconnected or the cable clip/holder has broken or something.

I am hoping it isn't the servo - have read/researched it is a PITA to switch out.

Any other ideas? I have pulled the electrical troubleshooting guides from the forums and may dig into that soon but I am too ADD to make it through all those steps at once...may take a bit to chug through it.

 

I had that problem when I fixed my PCV hose, turns out I had hit the cruise control cable and broke the clip. I zip tied it back on and haven't had a problem. It's on the passenger side of the throttle body. Hope it's as simple as mine was

 

Mine is 2007 E350 V10 (but does not have a throttle cable; like yours). the symptoms matched yours exactly.Next time its working, and then shuts off itself; press the "Resume" button. If it begins working then it's probably the master cylinder cut-off switch. I bought one (Motorcraft, even) from Rockauto.com for under $20 and since the install- mine has been 100%. "MOTORCRAFT SW6350 Cruise Control Release Switch $ 15.28"I handed it to my local Ford dealer during my oil change visit and they installed it for free.

 

The master cylinder switch was my first guess too----my own '03 E250 had this same intermittent operation.

The recall if done at the dealership is free of charge; parts labor etc.

I will confirm that switch from Ford is indeed just about $20 over the counter from the dealers too!

 

Thank you all!

Will take a look at it.

Added checking the cables and such tonight, going to look at the master cylinder switch in a few.

FYI - the cruise will not engage at all, I assume now that something is killing the signal (switch, etc)

 

Correct---IOW the safety defeats are working!

 

Mine got to that point also. (Not engaging at all).

 

I discovered this during the first shake down run of my new-to-me '03 E250, on my way to Pittsburg (Pixburg? ). The intermittent operation was a bit much to bear and luckily I carry a ton of tools with me. A quick snip and splicing of the wiring leading to the MC switch and its been fine ever since.

Once we get used to CC its tough to do without it!

 

Is there a troubleshooting setup I could do to rule it the switch? Unplug it and drive? arc the connectors? Just wondering which state it sends the kill signal.

 

To confirm its the MC switch just jumper the connector. I can't recall the terminal shape just now---let me check the replacement part, still laying in back cargo area.

A few minutes later.............

looks like a paper clip or piece of 18ga wire stripped each end could be inserted into the wiring connector as a jumper of sorts. Temporarily secure that cobbled up affair to assure it won't vibrate or jar loose during normal driving. If that does the trick its confirms that switch was/is the problem.

HTH

 

Jumped the connection and sadly got no change.

Kinda at a loss now...

 

If you drove it and no change then most likely its the servo itself---sorry to say.

I can post what I have about diagnosing the steering wheel switches as they are a bit unique in their communication with the servo.

Essentially you'd be doing a test for resistance at the large flat 10-pin connector leading into the servo. SW switches have different values which a microprocessor inside the servo read as what function is needed.

Lemme know!

 

Already got it out and taking a look at things. Checking to see if they motor is seized, checking voltage/resistance. Will check in later.

Thank you so much for the quick response - long duration troubleshooting can be exhausting!

 

quick update: took servo off. motor moves smooth, no binding on the cable. on to testing voltage/resistance on connectors...

 

Ok, got the multimeter out and checked voltage using this guide:

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If the switch is clean, back-probe the Light Blue/Black (LB/BK) wire at pin 5 of the speed control servo to check it for voltage with the servo connected and the ignition switch in the Run position.
Voltage should indicate 7.0-8.0 volts.

If there is no voltage on this circuit when the servo is connected with the ignition switch in the Run position, check the Light Blue/Pink (LB/PK) wire at pin 7 to verify it is indicating battery voltage from fuse 5 (15 amp) of the Central Junction Box (CJB) and check for battery power on the Black/Yellow (BK/YE) wire at pin 9 of the servo to verify it is good coming from the brake pressure switch and fuse 13 (20 amp) of the CJB.

If the power feeds check to be OK, verify that the LB/BK wire is not shorted to ground. This can be done by checking for the horn to blow when pressing the speed control On switch.
If the horn blows pushing the horn button but not the speed control on switch and the power supply feeds are good to the servo, the servo has a connection issue or is defective.

If the LB/BK wire indicates correct voltage with the key in the Run position, check the voltage while holding down the ON switch. This should cause the circuit to indicate battery voltage. Releasing the switch should cause the LB/BK wire to return to the 7.0-8.0 volt value.

Holding the SET/ACCEL button should cause the LB/BK wire to indicate approximately 4.5 volts. Releasing it should cause the LB/BK to return to the 7.0-8.0 volt value.

If the speed control switch values check to be OK, verify that the Tan/Light Blue (TN/LB) wire at pin 4 of the servo indicates to be a ground from the Brake Pedal Position (BPP) switch located above the brake pedal. When stepping on the brake pedal, this ground should turn into a battery voltage input signal.

The Vehicle Speed Sensor (VSS) input can be checked on the Grey/Black (GY/BK) wire at servo connector pin 3. This circuit should indicate a square wave signal with the transmission output shaft spinning fed from the Powertrain Control Module (PCM). The same circuit feeds the cluster for speedometer operation.

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The only part I failed was the part in BOLD RED above. The voltage went from 8V to 7V when pressing on rather than going from 8V to 12-14V. Makes me suspect of the switch itself now...