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The Bavarian
Join Date: Mar 2012
Location: Pfaffenhofen/Bavaria/Germany
Posts: 247
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Speedo output "A"
Hi,
while trying to track down the problem that keeps the cruise control of my '80 SC from working I found that the signal "A" from the speedometer to the cruise control brain (and the OXS milage counter) looks odd. Actually, the doesn't seem to be a meaningful signal.  Before I finally conclude that the speedo is shot, I would like to ask the following: - What is the output configuration of "A"? is it a relay contact, a transistor, or what? - How would a valid signal look like? I assume it would be some kind of frequency related to how fast the wheels turn. Is it a voltage (rectangular between 0 and 12 V)? - Any other idea how I can check the "A" signal? The speedometer is a VDO model 437.201/1/20 Thank you, Manfred Last edited by ManniB; 08-11-2013 at 11:22 PM.. |
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08-11-2013, 06:58 AM
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Registered
Join Date: Jul 2003
Location: Glorious Pac NW
Posts: 4,184
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Manfred, I can't answer your question because my car is in the shop and I can't stick a scope on the A terminal. However, I never realised the A terminal was output for the OXS sensor - so you've explained why I've never had to reset mine in 30,000 miles (it's not connected)...
I'd expect it would have a good chance of being a 5V square wave output though - that's what you get from the transmission sensor.
__________________
'77 S with '78 930 power and a few other things. |
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08-11-2013, 02:52 PM
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The Bavarian
Join Date: Mar 2012
Location: Pfaffenhofen/Bavaria/Germany
Posts: 247
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Quote:
 Hopefully I will find an answer for my questions, too. 
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08-11-2013, 11:26 PM
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The Bavarian
Join Date: Mar 2012
Location: Pfaffenhofen/Bavaria/Germany
Posts: 247
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Bump...
I can't believe that no one has an answer for me
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08-12-2013, 09:03 AM
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