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Registered
Join Date: Apr 2001
Location: Greenfield, IN
Posts: 412
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Sticking tach in a Carrera
Ever since I have owned my '84 Carrera, the tach "sticks" sometimes (actually more often than not). Usually at idle, it just sticks and sits at 600. Then I'll be driving along and it will spring back to life and work normally. Then it will drop and sit at 600 again. Sometimes it even sticks at other RPM's (2K, 4K, etc.). I replaced it w/ 2 other tachs and they all did the same thing, so I am suspecting it is not the tach, but the signal. Where does the tach get its signal from? Could it cause this symptom?
Colby |
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02-01-2002, 09:56 PM
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Registered
Join Date: Mar 2002
Location: orlando fl
Posts: 3
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erratic tach
the tach signal on 84 up motronic systems get their signal from the dme unit under drivers seat. terminals 11 & 21 are the outputs. One is for the upshift indicator light. this signal is pulsed and will require a digital multimeter with millisec/pulse width. I haven't been able to determine the normal reading but the signal is derived from information from the speed sensor on the crank which is sent to the dme unit...not the tach.
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03-08-2002, 06:29 PM
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