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Registered
Join Date: Jul 2002
Location: Ontario, Canada
Posts: 165
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Speedometer - "A" terminal solo???
Pulled out speedo on my 79SC to attach cruise wiring to the ground and "A" terminal as suggested by the Bentley.
To my surprise, there was nothing attached to my A-terminal. The Bentley has a white/red wire coming off it for the mileage counter apparently. Island911 was kind enough to take a pic of his speedo - and you can clearly see the white/red wire hanging off the A-terminal. So where's mine? What is this wire really for? Everything on my speedo works fine (trip, odo, etc.). I am troubleshooting cruise right now and wonder if my A-terminal is 'fuched'. 
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If opportunity doesn't knock, make a door. |
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08-30-2003, 05:30 AM
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Registered
Join Date: Dec 1999
Location: TX USA
Posts: 9,804
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Shawzy,
A P.O. probably removed the smog pump and EGR mileage counter at the same time! Those counters sometimes 'tick' rather loudy ... enough to drive some drivers crazy! NOTHING TO BE CONCERNED ABOUT ... unless you want your wiring to be 'factory' correct!!!
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Warren Hall, Jr. 1973 911S Targa ... 'Annie' 1968 340S Barracuda ... 'Rolling Thunder' |
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08-30-2003, 08:53 AM
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Registered
Join Date: Jul 2002
Location: Ontario, Canada
Posts: 165
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Thanks Warren
Smog pump is gone - I don't know what the EGR mileage counter is. Purpose? What does EGR stand for? I didn't assume I had anything to worry about as all guages etc work fine. Just seems like a funny coincedence that my cruise speedo signal may not be fine and it hangs off the missing EGR wire's terminal. MANY thanks for your input.
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If opportunity doesn't knock, make a door. |
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08-30-2003, 09:47 AM
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Registered
Join Date: Dec 1999
Location: TX USA
Posts: 9,804
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Shawzy,
EGR stands for Exhaust Gas Recirculation, and the warning lamp meant that it was time to replace the EGR valve.
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Warren Hall, Jr. 1973 911S Targa ... 'Annie' 1968 340S Barracuda ... 'Rolling Thunder' |
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08-30-2003, 10:31 AM
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Registered
Join Date: Jul 2002
Location: Ontario, Canada
Posts: 165
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Got it.
Mileage counter hung off speedo A-term and lit up a warning light accordingly for EGR valve. Thanks I opened up my speedo just now to see if anything looked obviously bad with the internal wiring to the A-term - looks fine. Here's a kicker though. I was buzzing out the little circuit board at the back of the speedo with the multimeter to check continuity etc. There are about 8 or so resistors on this board, the majority of which gave me no reading whatsoever - i.e. open circuit across them. How could this be??? I don't get it. Speedo and everything works fine, can't imagine that the majority of resistors on the board are for the A-terminal. Right now I am looking at trying another speedo in the car in my last attempt at OEM cruise.
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If opportunity doesn't knock, make a door. |
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08-30-2003, 11:48 AM
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Information Junky
Join Date: Mar 2001
Location: an island, upper left coast, USA
Posts: 73,189
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As best as I can surmise, the "A terminal" would need an oscilloscope(or tricks with a muli-meter) to test. My speculation is that the "A terminal" is the amplified pulse used to run the speedo, the O2 counter, and the cruise control modual. So, if the speedo is working, then the "A terminal" is likely working.
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Everyone you meet knows something you don't. - - - and a whole bunch of crap that is wrong. Disclaimer: the above was 2¢ worth. More information is available as my professional opinion, which is provided for an exorbitant fee. 
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08-30-2003, 03:24 PM
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