In a message dated 2/13/2001 6:09:30 PM Eastern Standard Time,
tr6taylor@webtv.net writes:
>> Can I assume that my (SEARS) Craftsman Engine Analyser is on the fritz
>> so far as the OHMS function selector goes? When I connect an oil
>> pressure switch to it, it reads 20, rather that ZERO, as you stated it
>> should. Then it will go to infinity when the switch is opened with air
>> pressure, as it should when the switch is OK. There is a 0-16V and
>> 16-32V selector, but doesn't change the reading much in either position.
Dick,
Either your analyser or the switch is on the fritz. It could be that the
switch contacts are bad, and are actually 20 ohms. Test your analyser by
clipping the leads together - if everything is OK, the meter should read
zero. Usually, there is a zero adjustment for the ohms scale (NOT the meter
needle adjustment), as the ohms circuit can vary quite a bit. If you don't
have the zero adjustment, either a) the analyser is a very good one, and
never needs adjusting, or, b) it is an average unit, and it was never
intended that the ohms scale be used for much more than open/short detection.
>> When you turn on the ignition key, both brake light and oil light bulbs
>> should glow, even if faintly. The brake light bulb comes on just to tell
>> you that the bulb is good, while the PWDA switch detects failure in one
>> of the two brake systems, and will stay on till whatever tripped the
>> switch is corrected.
>> Dan---How'd I do?!
You done good! If I just knew as much about the rest of the car as you do
about the electrical parts.....I don't even dream of knowing as much as you
about the mechanical stuff.
A little further clarification, though. If everything is working as it
should, the PDWA switch will NEVER be closed, but the oil pressure switch is
ALWAYS closed when the engine is off. If the two switches were wired
individualy to their respective bulbs, you would have no way of knowing if
the brake bulb was good or not. On the other hand, the oil light should
always be on until the engine is up to speed, so it is tested every time you
start the car. By wiring them together, the factory was able to "sneak" in a
test of the brake light.
Interestingly, the MGB designers added a manual switch on the dash to test
the brake light. The only way to test the bulb on an MGB is to press the
switch. I wonder what this says about the designer's opinion of the
intelligence of the typical MG owner vs the Triumph owner -- is this a good
or bad comment on us TR owners? (I also own an MGB, so I'm covered either way
<g>)
Dan Masters
Alcoa, Tennessee
Triumph TR 250 - TR6 Electrical Maintenance Handbook:
http://members.aol.com/danmas6/
Stuffing a V8 into a small British sports car:
http://members.aol.com/danmas/
British V8 Newsletter:
http://members.aol.com/danmas4/mgv8.htm
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