Does anyone know if Ford has a TSB for the cruise control surging problem?? Someone awhile back mentioned that it was an a ABS part that was causing the problem, but I do not remember the specifics.

 

Here is the link that I found for you. Don't know if the info is what you are looking for..


https://www.ford-trucks.com/forums/s...threadid=19182

 

I followed the link and printed the info to take to our dealer. We've had the same problem (at 70 mph) since we bought our vehicle.

Just wondering - ABS = Antilock Braking System, right? This is causing cruise control problem, or does ABS mean something else?

Thanks for the link, it's very helpful. I love this forum.

 

Beleive it or not: it is the Anti-Lock Braking System that causes the Cruise Control problem.

 

benr0,

Thanks for answering. ABS is not at all what I would have guessed. Do you have any idea how ABS can cause cruise to act up? Like others who posted in the link you provided, I've seen this at 70 +/- 2 mph, seems very speed specific.

Thanks again,

 

I really don't know the specifics of "why" but my guess is that when the ABS module is looking at the wheel speed its sending something back that causes the CC to act up?

 

The rear-end speed sensor is also the rear-wheel anti-lockup sensor, so it probably goes straight to the ABS module. From there, the EEC gets speed information.

Computer-wise, I can see the ABS module not giving updates on speed fast enough, so it makes it hard to keep the truck at a constant speed. Too much power, I think

A firmware update might be all that's needed, unless the hardware can't do the updates fast enough, so you need an upgraded module.

Keep us informed! I might be going to have the same thing done...

 

Well duh, I didn't really think about it but yeah, wheel speed probably goes through the ABS to the EEC. I noticed in the link to Super Duty site that one user said cleaing the vss sensors (is this what ABS uses?) fixed his problem. I thought about this but my vehicle has had problem since we bought it new.

It might be the ABS has some electrical problem that's been fixed in interface to the sensor? I don't know much about the sensor itself.

My first thought when it happened was there was some discontinuity in the curves used in cruise control and that it was just not going to be stable at that point. Maybe it's ABS firmware.

Oh well... fun to speculate when I really have no clue.

 

Oh... one more thing. It would seem if the ABS is able to work properly, the speed of the hardware (I assume you mean update rate) should be adequate for cruise control thoughout the vehicle's speed range. If it weren't fast enough, I would think the problem would get worse as you continue to increase speed, but it looks to me that it's only a limited range. It holds speed fine at 75 mph and up.

Later.

 

It's the "rate of change" that I'm talking about. The ABS may only update the EEC (cruise) at a certain rate, even though it's capable of monitoring the ABS sensors at a much higher rate. By the time the cruise realizes you are below 70MPH, you are already at 68. It punches the gas, accelerates fast, next update, damn, you're at 72. Decelerate, damn, overshot the mark, we're back at 68. Hit gas, repeat... I dare say, with the same program, a 5.4L wouldn't overshoot the high mark that much and wouldn't oscillate

The dealer's quick-fix is to replace the ABS module (and they get reimbursed a certain $ amount). They could probably update the firmware, but they wouldn't get as much money for hooking up a computer and letting it do the flash. If they turn wrenches they may get more shop time for the fix. Or, it's just Ford's way of dealing with it. Don't know...

One thing to think about - with OBD II, all computers onboard (EEC/tranny, and ABS) communicate on a "bus", or a network. Depending on how much crap is already on the network, and how fast the network itself is, there may not be enough bandwidth left to update the cruise fast enough. Maybe they just changed the priority on the cruise updates, or there was a buffer overflow that required better hardware. Either way, I'm going to push for this because I HATE my existing ABS program... it's so sensitive to lockup, it's not anti-lock, it's ANTI-STOP!