When I turn the cruise on then go to engage it. The cruise light flashes on the dash, but never engages. Any idea what it may be? Could it be a bad switch?

 

Has the recall been done? Does the brake light switch work properly?

 

All recalls have been performed.

 

Run the speed control self-diagnostic.

Check the switch on the brake master cylinder for fluid leakage and for continuity. Check the recall harness for continuity. Check the position-sensing portion of the BPP switch for proper operation. Check the connector of the cruise servo for corrosion, overheating. Check that connector for operating power.

 

Have you checked the third brake light? On F150s, if that has failed, the cruise control will not engage.

- Jack

 

That doesn't apply to a 2000 Expy.

 

Thanks, I didn't know, so thought it was worth posting.

- Jack

 

I forget what year it started for the F-series, somewhere around or shortly after '06 or so [Edit: It's 05, see below.]. I'd have to dig through each year's schematics to find it again.


The issue was that the input to the speed control module from the BPP switch (signalling half, not the brake lights), required a filament-based 3rd brake light bulb to pull down the logic input on the module. Without the pull-down, the input was always at a logic high which "told" the modules the brakes were applied. Previous models had that circuit paralleled with the ABS module which had an internal pull-down. I first ran into this assisting someone on one of those newer trucks who had lost cruise when they upgraded to to an LED 3rd brake light and figured it out.

Edit: I found the thread from years back that discussed this. See https://www.f150online.com/forums/el...t-working.html


In any event, there are several million trucks running around with SCDS switches that haven't leaked yet and that, in all likelihood, a fair percentage will still leak and fail before the truck retires from service. Sometimes the switch just goes "open" electrically, other times it leaks fluid and blows the inline fuse in the recall harness. Either will disable the speed control, but, at least with the second, you don't blow the main brake light fuse (if you're lucky) or the truck doesn't burn up (if you're not lucky).

 

I THINK, but of course I could be wrong, that the third brake light / cruise control linkage also applied to my 2005 F150. (At least I always thought it did.)

I've certainly offered the 3rd light solution often enough and had several people tell me I was right. Maybe they all had 06+ trucks.

- Jack

 

Had a few minutes to poke though the diagrams.

Looks like 05 is the first year for the F150 and 07 for the Expy for this situation. I didn't look at the Super Duty diagrams.

 

Thanks, buddy. I was hoping I wasn't getting senile all of a sudden!

- Jack

 

Hey, I'm surprised I remembered any of it at all....

 

As usual - you two guys are being overly modest. Ol' Bubber know'd better - I kin cipher sharp knives when I see's 'em.

Me? don't even ask me what I just had fer brekkie - not until me ginseng kicks in

 

I was not very specific.

It is an '02 5.4 4x4.

Thanks.