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Old 07-13-2003, 08:33 PM
rngadng rngadng is offline
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Join Date: Mar 2003
Location: Grand Rapids, MI
Posts: 10
CD Changer bus line

W124 E420 1995
CD Changer/Becker Radio (1492)/pre-installed CD line problem ("cd line")

Summary of problem: my pre-installed cd line (from the radio to the trunk) will not operate an otherwise operational CD changer because the cd line does not have the 12 volt charge at pin no. 5 of the 10 pin plug.

Cursory answer/question: If the simple answer is order a new cd line and install it, does the cd line operate any other equipment between the radio and trunk? I doubt it, but that possibility exists. Further, I would like to avoid installing a new line from the dash all the way to the trunk.

Synopsis of testing conducted:
We had two W124 E420s to conduct our tests (Mine--non working CD changer, and Willy's--with a fully operational CD changer)

--Mine would not operate either CD changer. Willy's would operate both. Thus the CD changer was not the problem.

--My radio in Willy's car would operate both CD changers, thus my radio was not the problem.

--Thus, the only different item remaining was the CD line.

--With a multimeter, we checked for voltage on each the pins of the trunk plug when the line was plugged into the "C" plug on the back of the radio for both my cd line and Willy's cd line.
Willy's line/pins My line/pins
no. 1 = 0 volts no. 1 = 4.5 volts
no. 2 = 0 volts no. 2 = 4.5 volts
no. 3 = 0 volts no. 3 = 4.5 volts
no. 4 = 12 volts no. 4 = 12 volts
no. 5 = 12 volts no. 5 = 0 volts
no. 6 = 0 volts no. 6 = 12 volts
no. 7 = 12 volts no. 7 = 12 volts
no. 8 = 0 volts no. 8 = 0 volts
no. 9 = 0 volts no. 9 = 0 volts
no. 10= no pin no. 10 = no pin

As noted above, while Willy's line had 12 volts at the no. 5 pin, mine had 0. And, for some reason, my line had 12 volts at the no. 6 pin, while Willy's had 0. Plus, the 4.5 volts at pins 1 thru 3 makes no sense!

With my line, is there some way to just switch the line from no. 6 to no. 5? The color coded lines leads me to believe that this cannot be done.

Otherwise, any ideas to fix this situation?
Thanks in advance.
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