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Intermittent Cruise Control

1K views 9 replies 2 participants last post by  klhansen 
#1 ·
About 90% of the time, when I am at my desired set speed, I push the "on" and the "set" buttons, the CC works. Sometimes I have to push them a couple of times. Once operating, the CC will always resume the set speed after braking or stopping.

However, here is the real problem. Operating EITHER the Accel or Decel will almost always (95%) turn the CC off. The only way I can set speed is to throttle up again and then hit "on" and "set."

There are so many posts on Inet about the brake master cylinder pressure switch being the number one cause of problems that I replaced it. No change.

Since the CC basically works, I am stumped. Any help will be appreciated.
 
#2 ·
I would get hold of a scan tool that will do a KOER Switch test, such as AutoEnginuity.
I suspect the steering wheel buttons are going bad on you or the clock spring that connects them to the rest of the truck is bad.
The KOER Switch test will check all the buttons and give you a report on which ones don't work. You initiate the test and press all the buttons on the steering wheel.
 
#3 ·
Kl, Thanks. This definitely sounds like the way to go.

1. Where would you suggest I look for the tool?
2. Do I need to buy it, or rent it, or pay someone to scan it for me?
3. My truck is for sale. If I buy it, will it be of any use on my 2019 F150 I have on order?
 
#4 · (Edited)
  1. You can buy AE from a number of vendors, or directly from https://www.autoenginuity.com/. You'll need the Ford Enhanced package.
  2. You can buy (see above). Rent? - no idea if anyone rents AE (the loaner scan tools from the auto parts stores won't work). You could ask if a member here near you could help out.
  3. Yes, it would work on any Ford, assuming you have the current version.

If you do any work on your vehicles, it's a handy tool to have for diagnosis.
 
#5 ·
I have found a couple of procedures to try and see if I can narrow down the problem. This one is for GAS engine and do not know if it will work but am going to try it.

TEST 1. Self-Test Diagnostics

WARNING: This test is a key on engine off (KOEO) test only that is conducted in PARK only with the emergency brake fully engaged.

Enter the Self-Test Diagnostics by depressing the speed control OFF switch while turning the ignition key ON, making sure the engine does not start and is not running. The speed control indicator on the instrument panel will flash once to indicate that speed control module entered the diagnostic mode. Five additional flashes at this point indicate a defective speed control servo. Release the OFF switch.
Press the remaining switches in this sequence: ON, RESUME, COAST and SET/ACCEL.
If the "ON" switch is not depressed within five seconds after entering the diagnostic mode, the module times out and the procedure must be started over.
The speed control indicator lamp will flash as each switch is depressed. Press each switch in the sequence immediately after the indicator light goes out for the previous switch.
NOTE: There will be a slight delay when the last button is pressed and the lamp flashes.

A lamp flash with the last button (SET/ACCEL) indicates that the STATIC test passed. If the lamp does not flash with the last button and there are no additional flashes of the lamp, the switch is defective.
If the lamp does not flash with the last button, and additional flashes occur, follow the chart below for trouble codes:

Flashes Source
2 Flashes BPP defective, circuit is defective, brake applied, CPP switch or jumper (if equipped) is defective
3 Flashes Deactivator switch is open or circuit defective
4 Flashes Vehicle speed signal is out of range or circuit is defective

Immediately after the STATIC test, the speed control servo does a DYNAMIC test by automatically actuating the throttle lever from 8 mm (0.315 in) to 12 mm (0.472 in) of travel from the idle position. During the DYNAMIC throttle pull, observe throttle movement to witness any binding or sticking of the speed control cable and correct connection of speed control cable to throttle lever. Make sure the throttle returns back to the idle position.
Return the ignition switch to the OFF position and proceed to the Symptom Chart.

TEST 2.

https://www.youtube.com/watch?time_continue=4&v=4MoxLMkW_jk

I think to run this test for diesel, I have to find a connector from the CC switches to the PCM to tap into.
 
#6 ·
I have not seen any mention of a "lamp flash test" in the service manuals, so whether that would work on your truck is very questionable.

The video you posted is for a gasser truck. The diesels don't have a throttle so therefore don't need a cruise control servo. They're strictly "drive-by-wire", with the PCM controlling the injectors directly electronically.

On some trucks pushing a combination of the cruise control buttons will make the horn honk, as it shares part of the circuit with the cruise buttons, so that might confirm the circuits are OK, but I don't recall the combination. The cruise buttons just connect different resistances to the PCM, which figures out which button is pushed from the resulting voltage signal and responds accordingly.
 
#7 · (Edited)
The video you posted is for a gasser truck. The diesels don't have a throttle so therefore don't need a cruise control servo. They're strictly "drive-by-wire", with the PCM controlling the injectors directly electronically.

On some trucks pushing a combination of the cruise control buttons will make the horn honk, as it shares part of the circuit with the cruise buttons, so that might confirm the circuits are OK, but I don't recall the combination. The cruise buttons just connect different resistances to the PCM, which figures out which button is pushed from the resulting voltage signal and responds accordingly.
On the video that is exactly why I said I need to find a connection to the PCM to tap....not to a servo. If I can find a connector to tap, then I can measure the switch resistance values. Anyone know exactly where I can tap into a connector to get these readings?
 
#8 · (Edited)
Here's some info that might help you. The connector is on the steering column just behind the dash. You could check continuity of each of the buttons. The clock spring is probably the most vulnerable piece of the system, and you may have to turn the wheel to check it while it's flexing. It may connect in some steering wheel positions and not others.
Just pull the connector apart and test with your meter on the steering wheel side of the connection. If you probe it with it connected you'll get unreliable resistance readings because you'd be measuring the stuff on the opposite side as well.
 

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#9 ·
KL,

Thanks much for your help. Good info. Here is what solved my problem.



CC works perfectly now. Did not know/remember that switches were supposed to light up. Some do now. Pretty apparent that permanent fix will be replacing the switches / harness.

CASE CLOSED!
 
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#10 ·
Good work!
And thanks for sharing the fix. :thumbsup:
 
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