Cruise Control Switch Wiring Diagrams?

[eb99603]

Anyone out there have cruise control switch wiring diagrams for a Setra? (Looking at you, BK )

I have the DDEC diagrams telling me what wires on the Vehicle Interface harness should be making their way up to the cruise switches, but nothing telling me how to correctly wire the 6-8 pins on each of the 3 connectors (on/off, set/accel, coast/resume). I have a bit of a hairball under the dash with some previous owner's "fix", and cruise does not disengage when the brake is applied. I'm determined to get that fixed.

[luvrbus]

That is the OEM wiring the Setra maybe different but I doubt it, the feed come from the cruise enable switch (off) then to the resume,next the set/ coast then to brake switch(on)

[eb99603]

What I have in the bus looks nothing like any of the diagrams I have.

From the DDECII -> DDECIV conversion


From the DDECIII wiring diagram I have in my owner's manual:


From the DDECII wiring diagram I got from Setra/MCI today:


What I have:




So going into the On/Off switch:
* Wire 542
* The Hairball

Going into the Set/Coast switch:
* Wire 541
* Pigtail of The Hairball

Going into the Resume/Accel switch:
* Wire 545
* Pigtail of The Hairball
* Wire 544

The Hairball has:
* one thin black wire going straight through into the On/Off switch.
* two different black w/white wires spliced in through quick connects.

[eb99603]

Oh, and let's not forget that there are far more pins on the back of these switches than are actually in use.

[luvrbus]

I have been working in the same area for a week I installed new rosewood inserts panels with new switches and now I have lost the fast idle feature that did work before.I have both the DDEC and OEM Responsibility schematics and still cannot figure the thing out     

[eb99603]

If I'm reading everything right. I think my hairball needs #542 spliced into it. Where #542 is currently going into the On/Off switch (I think that's Pin 1), I need to put wire #953, which is simply ground so that's easy.

And then I'd sure like to figure out where the heck those other two black w/white wires in my hairball go. But those should be able to be removed. As long as one of the 3 wires on my hairball go to pin 80 on relay 11a, I think I can ditch the others.

Man! I wish it wasn't midnight and my bus wasn't missing two alternators. I'd love to go try out this theory!

[luvrbus]

Mine has a black wire from the set switch that controls the fast idle you just tap it for idle speed that were I am having problems the preset fast idle works.With a series 60 I want to be able to set the idle at about 50 or 75 more rpm at idle.

I do not like the shaking of the 60 series on idle and the fast idle switch is to many rpms for me lol there has been to many of the old 2 strokes idling so smooth in my life 

[eb99603]

One of the wires in my hairball was in fact ground. So that made finding a ground relatively easy.

Pin 80 on the relay was actually pin 30. And the thin wire leading into the hairball actually went to it pin 30.

After cleaning things up a bit, I *think* I have it wired correctly now. Eagerly awaiting my new alternators so I can test it out!

[eb99603]

Swing and a miss. Cruise still doesn't disable. But I *think* my wiring mods were correct. I just never hear the relay trip when the brake or retarder is applied. Swapped relays, still no click. When I have someone else with me, I'll have them jump the terminals at the relay and see if cruise disables. If so, then I start chasing wires to see why I'm not getting anything at this relay.

[eb99603]

Hey folks. I'm chin deep in getting my cruise control switches working. I will fix this before departing in a few weeks. I've spent far too much time chasing wires already, but I'm now stuck on the retarder.

I have a few diagrams for DDEC2 (which is what my bus had original) and DDECIII (which is what my bus has now) but *nothing* I have mentions the transmission I have. Everything references a B500 and I have an HT-748.

Anyway, so I was able to figure out the brake light wiring and how it makes its way through the series of relays to finally trip the relay that disables cruise. Had to swap two relays but now that correctly clicks over when the brakes are applied. Where I'm caught up now is in the retarder wiring, as this too should disable cruise.

Let's start with the DDEC3 diagram.


The retarder and the brake light should energize the coil on relay 11a (that's my cruise disable relay). In the non-engergized position it allows wire 538 from the cruise switches to continue to wire 531 at the DDEC. That wire is "Service brake released". There's also a retarder switch that seems to be powered by +5V, and some mystery wire 171. This is supposed to make its way to wire 543 at the DDEC which is labeled "Cruise control off" on my diagram.

I have absolutely NO idea where this retarder switch exists, or if it even exists on an HT748 not a WT-B500. I have no idea what (if anything?) I should be sending to wire 543 on the DDEC. I do see two pressure switches in the air lines leaving the retarder. One is hooked up to 24V power which continues on to the RET light on the dash. The other is hooked up to 12V power on one side, and lord knows what on the other. I can't figure out where these wires go.

Any thoughts out there from any of you?

[eb99603]

Here's my relay 11a configuration today. Note that it matches the DDECII wiring diagram I got from Setra.



So what the heck are wires 543 and 531. What does the DDEC _expect_ them to be. In reading some other posts on the interweb it looks like you need 543 to be ground for cruise to work. Which it is, since 538 coming into the switched side of 11a goes through to 543 in the non-energized position. 538 is the switched ground from the cruise control on/off switch.

But what throws me is 531. Someone said that also needs to be ground for fast idle to work via cruise control. I have a separate high idle switch, so that's not my issue but it makes me think 531 is supposed to go to ground in the cruise-enabled situation. But my 531 never makes it to ground today and my cruise turns on.   Because relay 11a was never energizing before, 543 was always grounded when cruise was on and 531 never was.

Looking at the diagrams again it seems the DDEC3 diagrams tell me that 543 should always be grounded in "on" operation. If I had a B500 trans, when the retarder was enabled 543 would no longer be grounded and would instead receive +5V. This would disable cruise.

It also seems that 531 should always be grounded in "on" operation. By the DDEC3 diagram, hitting the brake and energizing relay 11a should break the ground for 531 and disable cruise this way as well. That's all well and good except for the fact that this "break the ground for 531" scenario which should prevent cruise from working is precisely the scenario that's happening right now in my bus and cruise is enabled/working.

I don't understand how 531 and 543 relate to one another.  

[luvrbus]

I found my problem 531 needs to be grounded for the fast idle all I know about 543 is it is a digital input wire ? do have the installation and application manual   

[eb99603]

luvrbus, glad to see you were able to get your issue squared away. I can't follow your last sentence - were you offering your installation/application manual? Or were you asking if I have them? And if it's the latter, installation/application manuals for what?

[belfert]

I think it is very common for switches to have unused terminals.  The manufacturer can use the same type of switch for many different applications.  My Dina bus has many of the same basic switch, but they have different terminals connected depending on the application.

[eb99603]

Yeah, I ended up giving a big old {shrug} to the pile of pins on the back of the switches.

My concern now is what the DDEC expects.