Another "What is it?"

bwze · September 03, 2011, 02:56:36 PM

It's on a '64 GM PD4106.....located on the engine firewall to the left of the oil pressure sending unit and the low oil pressure switch. It's wired along with the stop light switch circuit. When you apply the brakes, it get's 12 volts just like the brake lights. The air line curving beneath it tees into the left side and then provides air to the stop and fast idle solenoids....on the other side an air line exits, turns 90 degree down and is the straight line you see behind the curving air line. I can't follow the straight line because is dives through the firewall and I don't feel like jacking and blocking to see where it goes. I see no reference to it in my manual or supplement, but I know the later model 4106s had some alterations in some areas. Any ideas?

travlinman · September 03, 2011, 06:29:19 PM

FWIW,

#674 does not have that....

TM

bwze · September 04, 2011, 06:46:19 AM

Thanks, I may try troubleshooting by killing the power to it and see what happens.

TedsBUSted · September 05, 2011, 05:36:54 PM

FWIW, another '64, #??? doesn't have it.

papatony · September 05, 2011, 07:13:50 PM

My 4106 has two of these one controls the fast idle the other is the engine governor control. I don't think it will run without it. the 62 4106 also had two.

TedsBUSted · September 05, 2011, 07:51:36 PM

Papatony - Maybe you're confusing the "bwze mystery valve" with the two standard solenoid valves which are located further towards the driver's side?

Ted

papatony · September 05, 2011, 09:34:29 PM

I'llheck it again

bwze · September 06, 2011, 03:20:54 AM

I didn't get a chance to do any further troubleshooting. I may get some time this week.

AndyG · September 06, 2011, 06:12:41 AM

I think that the fast idle only works when you are sitting still. Maybe that "do-dad" is what makes that work on your bus. If you release the parking brake or put it in gear it will return to regular idle speed.

bwze · September 06, 2011, 06:47:36 AM

No, I wrestled with that a few months back. There's a pressure switch that works with park brake valve located in the tool bay beneath the drivers seat that controls the fast idle relay.

This thing only sees power when the brake foot pedal is pressed and the stop switch closes.

Len Silva · September 06, 2011, 06:55:25 AM

Could it have been for a trailer brake controller? Perhaps the line that disappears, terminates at the rear bumper?

bevans6 · September 06, 2011, 07:19:18 AM

In my bus manual - an MCI, but still - there is an option for Expello moisture ejectors on the air tanks. The moisture ejector is air-controlled by a Skinner valve that is controlled by the brake light switch. I bet that's it, if you have a moisture ejector or used to have, anyway.

Brian

bwze · September 06, 2011, 08:02:40 AM

Len, the line is headed back towards the front, so I'm thinking that may not be it.

bevans6, that makes a lot of sense.....now I want to block and jack just to see where it goes....

RJ · September 06, 2011, 05:08:43 PM

Bill -

I'm not sure what that is either, my '64 didn't have it.

Perhaps a call to Luke, with a request that he look at this thread, might help solve the mystery before you start crawling around underneath?
1-888-262-2434 between 9 - 5 M - F Eastern.

FWIW & HTH. . .

travlinman · September 06, 2011, 05:37:49 PM

Long shot here, how about supply to an air actuated toad braking system?

TM