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muddywater
Senior Member

USA
50 Posts

Posted - 03/11/2020 :  09:32:34 AM  Show Profile  Send muddywater a Yahoo! Message  Reply with Quote
Thank you, to all on this forum!
Working on a 2007 Thomas C2. Last 6 of Vin # W02550. Air Drum Brakes.
All brake lights are out. This has a switch hub module P/N TBB 101420 revised to P/N TBB 154622.
What I'd like to know is how are the brake lights activated, air switch, or electric only switch? Can anybody help me locate that switch, and which wire coming into the switch hub module (SHM) activates the module to energize the brake lights?
I've am frustrated looking for where the lights get there signal from.
Thanks for any insight you can provide. Vaughn

Bluenozer
Top Member

Canada
640 Posts

Posted - 03/11/2020 :  09:46:16 AM  Show Profile  Reply with Quote
should have an air manifold on it ( plug will have four wires in it, and three air lines) air switch this will located in frt. of rear end or just behind tranny
sends signal to CHM plug 3 pin g
output to brake lights is from CHM plug 1 pin N for left and pin L for right
the wire that goes to CHM C3C splits when it goes over frame rail , if the wire that goes toward the frt. breaks unit will not shift " out of range" tranny does not see brake signal

OEM trained in wiring and all engine platforms for over 20 years
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muddywater
Senior Member

USA
50 Posts

Posted - 03/11/2020 :  11:26:14 AM  Show Profile  Send muddywater a Yahoo! Message  Reply with Quote
Bluenozer;
Thank you, I found the switch with 4 wires, 2 brown (black) with white stripe, 2 red wires with white stripe, above rear axle. CHM located just behind trany and on the drivers side. Do the brake lights go through the SHM or the CHM? Your much appreciated advise states "CHM plug 1 pin N for left and L for right brake output." My problem is that my CMH plug 1 is not used, it's seal capped. Do I need to look in the SHM for these terminals? Again thanks... Vaughn
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tigger2
Advanced Member

USA
469 Posts

Posted - 03/11/2020 :  11:56:16 AM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
The air manifold Bluenozer is talking about is a long black series of plastic module sections held together with stainless clips. the block asy. is held in the bracket by a plate with two or three bolts in front. the most common brake switch module is a NRG 27 SWA 110R this a Freightliner number.
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tigger2
Advanced Member

USA
469 Posts

Posted - 03/11/2020 :  11:58:33 AM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
make sure your looking at the right module there could be two the expansion module has caps on some connectors the main chassis module uses all of the plugs.
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Bluenozer
Top Member

Canada
640 Posts

Posted - 03/12/2020 :  02:46:05 AM  Show Profile  Reply with Quote
did they use plug C2 pin D it is for trailers but I've seen bodybuilders use these outputs before, and there could be two CHM like tigger2 stated

OEM trained in wiring and all engine platforms for over 20 years
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muddywater
Senior Member

USA
50 Posts

Posted - 03/12/2020 :  06:02:54 AM  Show Profile  Send muddywater a Yahoo! Message  Reply with Quote
Update;
Again Thank you to those who have responded, it's been very helpful!!!
As Bluenozer, and tigger2 explained, the brake light switch is right there above the front of the rear axle bolted in the frame crossmember.
As for the CHM module, if you find the CORRECT, CHM module, (this bus has one about a foot behind and to the left of the trany hanging vertically inside the frame rail, and another mounted horizontally, in front and above of the outside of the frame just behind the mud flap). This one has the correct wiring configuration.
I pulled the brake switch down, (thank you again tigger2) yes it is a NRG27 SWA 110R switch, and while handling it got the brake lights to start functioning. Pulled the wires out of the plug going into the switch, checked, found no broken wires, so I have ordered the brake light switch.
Again THANK YOU for your help, it has saved me a very large amount of time and frustration with this problem. This forums collective knowledge and willingness to help each other, is very appreciated by myself and others. Vaughn
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Bluenozer
Top Member

Canada
640 Posts

Posted - 03/12/2020 :  07:05:46 AM  Show Profile  Reply with Quote
spread pins in plug to AMU

OEM trained in wiring and all engine platforms for over 20 years
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tigger2
Advanced Member

USA
469 Posts

Posted - 03/16/2020 :  11:08:33 AM  Show Profile  Click to see tigger2's MSN Messenger address  Reply with Quote
The crap squared units have a steep learning curve, we who go first will lead.
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muddywater
Senior Member

USA
50 Posts

Posted - 04/16/2020 :  07:50:56 AM  Show Profile  Send muddywater a Yahoo! Message  Reply with Quote
Update;
Replaced the air manifold/switch that bluenozer and tigger2 focused me on. That solved the problem for me. Thanks again for your guidance with this problem.

How much was that "guy-in-tie" paid to design that convoluted "C" clip held together albatross?

Thanks again for your help, vaughn
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