I have a 2003 Supercrew that has developed a couple of issues with CC and the Autolock function. When I bought the truck in Sept. the Autolock would lock the doors whenever you put the truck in drive and let off the brake and the truck started to move! Since it has turned colder sometimes it will lock doors as usual and sometimes you may get 5 miles before they lock. Also I've noticed that untill the doors lock Cruise will not engage but as soon as they lock cruise works fine. the only thing I could think of that might effect both systems would be the brake pedal since applying brakes would disengage cruise and autolock does its thing when you release the brake. however my brake lights work normally. Any Ideas?

 

I went by the dealer today and purchased a new pressure switch for the master cylinder hoping that might be the problem. It was only $19 and I figured it was cheap insurance in case it turned out to be the cause of my problems. I was also concerned that I might have one of those fireball switches that might have slipped through the cracks. I Changed it out and the problem persists. I would just disable the autolock function if that were the only issue, but it gets on my nerves that I have to wait for sometimes several miles to be able to set the cruise. and if I have to brake for traffic I have to wait a bit before resume will pick up. the problem seems to me to be connected somehow to the use of the brakes.

 

Sorry it took so long, between work and snow removal tonight.

The common item I see here is the BPP ( Brake Pedal Position ) Switch.

Do you know if your brake lamps are taking a long time to turn off after releasing the brake pedal ?

The CC has the BPP & the secondary safety switch ( the recall 05S28 is the switch and the additional harness extension with an inline fuse ).

If either of these are set, the CC will not work, but I would expect the BPP to have the brake lamps illuminated as well.

work a check to see if the brake lamps drop out straight away after taking your foot off the brake pedal

 

Brake lights work perfectly on at the slightest touch of the pedal and off immediately when pedal is released. The problem seems to also be associated with ambient temperature as during cold snaps it seems to get worse and seems somewhat better on warm days or after the truck has been running for 30 minutes or so and is warmed up good. I was wondering if perhaps the BPP switch might be a multi-pole switch. with different functions hooked to different poles?

 

BPP does have a different set of contacts in it for the speed control part.

Speed control is a SPDT switch.
- Brake off is ground ( black wire ) is switched to the speed servo ( Red w/ light green stripe wire ).
- Brake on cab fuse panel fuse #15 ( white w/ yellow stripe wire ) is switched to the speed servo ( Red w/ light green stripe wire ).
-- This is looking at the EVTM cell 31 for the speed control, which usually shows the pedals as not pressed, and the internal switch is showing to ground.

The CSM for the autolock shows the circuit used is the same one for the CC ( the output of the Red w/ light green stripe wire ) is what triggers the CSM for the lock event.

The brake lamps themselves is cab fuse panel fuse #13 to Light Green w/ red stripe wire ) to light green wire.

Connector has 5 wires to it, and I seem to recall it is a 5 pin connector ( could be a 6 position connector, don't have a picture of C252 handy to check ).

Maybe time to check if half of the switch is holding up. I was figuring a plunger issue when cold, that is why I asked about the brake lamps.

Looks to be a contact issue in the switch itself, for only the CC section ?

Unplug the connector, and stick a meter probe in the white w/ yellow stripe wire position and Red w/ light green stripe wire position, and operate the brake pedal, to see if it is hanging up.
- Keep in mind you want the switch to be cold when you are doing this, just to replicate the issue.

 

Issue Solved thanks to the help of SSCULLY! I replaced the BPP switch this afternoon and now my autolock and cruise control are working like new! Thanks!!!

 

SSCULLY Rocks for sure! Knows his stuff