Can't Cruise

[scatter-SMB]

Well, I finally replaced my old, heat cracked engine wiring harness on my '07 with 6.0. Feel much better out in the boonies now after having a few starting hassles.

But.... Now my cruise control doesn't work. I have the service manuals which give the very long testing procedure with a VOM and test points. That looks like it will take forever.
So, anyone have an idea what might have happened? Is there any way that the new harness could have been connected wrong? The engine runs great so I assume all is well there? I don't see how the wiring harness would have done it.
Any ideas?

 

[1der]

Typically a missing ground connection is first place to look. l would check all the grounds in the schematic.

Also, I would check to see if the harnesses were exactly matched in terms of wire fills and placement in the connectors.

I am not an electrical guru like others here!:e5: but do like logical approaches.

 

[boywonder]

Brake Master cyl pressure switch? ...not sure if the diesel runs this same setup....


Common problem.

 

[WhitH]

I was going to suggest this as well and I can confirm the 6.0 diesel does have one of these and they do fail. Simple cheap fix if so, heres hoping that’s it.

 

[scatter-SMB]

Thanks for the imput guys.
I'm afraid that 1der is probably right. Especially after having replaced so much wiring.
And yes, the first place I went was to the master cylinder. Pulled the wire off and put a jumper on it. Still no joy.
Arggg, what a pain in the butt.

 

[JWA-SMB]

Thanks for the imput guys.
I'm afraid that 1der is probably right. Especially after having replaced so much wiring.
And yes, the first place I went was to the master cylinder. Pulled the wire off and put a jumper on it. Still no joy.
Arggg, what a pain in the butt.

I've also replaced the actual MC safety switch with a makeshift jumper to no success myself. What I did then was disconnect the existing safety switch with a known good working part temporarily lashing it in place near a hard brake line etc. Seems to make a difference for some reason.

Try that for now---might work out perfectly before digging in to too much work.

 

[scatter-SMB]

Hummmm, I thot that jumping it was the best way of checking if the pressure switch was bad.
Easy enough to get a new one and I'll give that a try. But, I'm pretty sure it's somewhere in the wiring seeing as how the harness was replaced. But where???

 

[boywonder]

One (or both) youtube videos discuss the switch states when depressing the brake pedal......and how that switch is wired in series with the mechanical switch on the brake pedal for redundancy.

Jumping the pressure switch wires assumes that the switch is normally open(NO)......it may not be.....I didn't pay enough attention to the videos

 

[Steve_382]

I have had to replace the switch on mine twice over the years.

 

[Big_ern_101]

Attached the Mitchell diagnostic procedures for the cruise control for an 07 with the 6.0 diesel.

After the basic checks, you are gonna need a decent scan tool to go much further.

 

[1der]

Attached the Mitchell diagnostic procedures for the cruise control for an 07 with the 6.0 diesel.

After the basic checks, you are gonna need a decent scan tool to go much further.

I am going need a clean up crew to gather up my brain matter!!! Holy sheesh, there is crazy amount of info in that link

 

[Big_ern_101]

I am going need a clean up crew to gather up my brain matter!!! Holy sheesh, there is crazy amount of info in that link

The diesels are pretty simple-forward. The cruise control is 100% electronic - as long as it has all the inputs made and all the conditions are correct, it will work 100% of the time. Follow the diagnostic procedures in order and you will have working cruise at the end of the day.

 

[1der]

I was perusing the rest of the website! That is incredible!

 

[scatter-SMB]

That looks to be easier to follow than the one in Ford's service manal. Thanks!
I have to leave today and won't be back for a week, but I'll let you know what I find.

 

[bosco53]

I've been having trouble trying to figure out the cruise control on my 2006 RB50 6.0 as well. I've replaced the pressure switch and the control buttons and no love yet.

Thanks Big_ern_101 for that file! I'm gonna have another go with that. :b5:

 

[scatter-SMB]

Well, made it back home and spent a few hours checking what I could. I pulled the connector off of the master cyl. and jumped it and then left it open. Didn't make a difference. Still no cruise. Checked all the connections I could and still nothing.
I'm going to take it back to the guys that installed the wiring harness as I don't have the tester called for in the manual and the info from Big_ern_101

I'll post what is, or isn't found.

 

[kbeefy]

Attached the Mitchell diagnostic procedures for the cruise control for an 07 with the 6.0 diesel.

After the basic checks, you are gonna need a decent scan tool to go much further.

Thanks! I'm going to use this when I get home, hopefully avoid a trip to the dealer.

 

[scatter-SMB]

Well, the cruise is now working. That's the good news. The bad news is that I had to take it to the dealership as I couldn't locate the problem myself. I assumed it was a bad connection, but couldn't find it.

They found the problem to be, and I quote:

"found an open circuit between brake pressure deactivation switch connector C1025 pin 2 and PCM connector C1381E pin 46"

They ran a jumper wire between from the brake pressure switch to the PCM. Easy peasy - except for writing the check. Dealerships ain't cheap.

So, all's well that ends well as they say. Now to take a trip!!

 

[bosco53]

Stoked it's working for you now! I ended up doing the same thing. But the kicker was the dealership came back saying the tech went out for test run and the cruise worked fine. Gave me a bunch of BS on how you have to be going at least 28mph and whatnot. I rolled my eyes hard!! "Do I look dumb to you?" I drove that van to Salado, Texas and back from San Diego for the eclipse in April. Tried engaging the cruise many times. They did end up telling me there was a trouble code related to cruise control deeper in the system. I'm willing to bet the tech cleared that first and then it worked. But they were insistent that he cleared it afterwards. They were kind enough to find a few other issues, leaking injector, leaking high pressure power steering line, etc. so they still got their hefty sum. But man, was that frustrating. I should be able to see any trouble codes the dealership can. But even with my FICM and another not-cheap code reader, I was getting nothing at home.

 

[scatter-SMB]

Yeah I hear you. I really hate having to go to a dealership, but sometimes it's the only option. I've worked in and run seveal shops, but when you need their expensive test equipment, you need it.

Glad yours is working too.