Switches

[Jon Kabbe]

On my 1977 coach I have two switches that I have no idea what they do. One is marked "ACC" and the other is marked "OVER-RIDE". I'm in the planning stages of adding the booster pump for the front heater/defroster and I need to add a switch. If I can use one of these spaces I can avoid drilling a new hole.

Thanks.

[John Leuenberger]

Jon, Was told by another Newell owner that the "over ride" switch is to release the air brakes which are designed to go full on if air pressure is lost. I have some mystery switches too and will probably remain so until can visit Newell factory.

[Jon Kabbe]

I can't understand how an electrical signal can prevent the parking brakes from kicking in due to low pressure. I believe that the parking brake is just an air pressure versus spring pressure balance--when the air pressure gets low, the springs just kick in and there is nothing we can do about it without more air pressure. But I could be wrong and thanks for the thought. I'll have to do some more tracing of wires.

[67 Goat]

Jon, My 1978 had a switch connected to the oil pressure switch that would shut the engine down if the oil pressure dropped. The "override" switch bypasses the oil pressure requirement during start-up. The switch is spring loaded to the off position. I found this set up somewhat troublesome so I eliminated it. A P/O may have done the same on your coach.

[Steve Saraga]

Jon,

I'm not sure on the "ACC" switch, but I believe the "override " switch is for the radiator fan. When in override, the fan run's continually and bypasses the thermostat, very helpfull on those long uphill pulls. [Editor's note: Newell's of this vintage were not factory equiped with temperature controlled fans. Therefore, this switch would not be an override for such a fan unless the fan and switch were added later.]

[Mike]

Jon,
if your engine has a problem i.e. overheating, oil pressure
a warning light will come on, this is followed by an engine shut down. The OVERIDE switch overides the shut down for a short time (we are talking seconds) to enable you to get the coach to a safe place & out of traffic.
Mike
[TechTalk Editor: Actually, the system works slightly differently than explained above. On the Cummins '555' the manual override switch has to be held on (spring loaded position) in order for the engine to start. Once sufficient oil pressure was obtained the oil pressure override switch
can be released. If the engine loses oil pressure, this system will probably shut the engine down, except when the switch is held open, as suggested above. However, the switch is not related to engine temperature shutdown.]

[Jim Cordner]

Jon, I have a 1977 coach with a Cummins '555' engine. As suggested by Mike Clarke above "The override switch on the Cummins '555' (the manual override switch) has to be held on (spring loaded position) in order for the engine to start. Once sufficient oil pressure was obtained, the oil pressure override switch can be released. If the engine loses oil pressure, this system will probably shut the engine down, except when the switch is held open".
However on my coach, the switch is in series with the high temperature safety as well. Either loss of oil pressure or high engine temperature will shut down the engine. The override will allow a brief start to pull off to a safe area.I had to use it several times on long summer hill climbs in Arizona when the old girl got too hot. A P/O had by-passed both safety switches but I have reconnected them, and rely on them doing their job to protect the engine. You may have to trace some wiring to see which configuration you have.
Enjoy.

[Jon Kabbe]

Ah, now I get it. Thanks to all who have participated in this discussion. My coach originally had the 555 engine, but it was replaced with a 6V92T. Since the STOP coil works in reverse of that on the 555 my OVERRIDE now does exactly nothing. I suppose I could install a relay to reverse the signals and then create an automatic stop on low oil pressure, hmmmm something to think about. Thanks to all for clearing this up.