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Home >> Saturn >> 1992 >> SC L4-1.9L DOHC VIN 7 >> Repair and Diagnosis >> Powertrain Management >> Computers and Control Systems >> Shift Light >> Description and Operation
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Shift Light: Description and Operation


PCM Wiring.:









PURPOSE
The upshift telltale is used, on vehicles equipped with a manual transaxle, to signal the driver to upshift. On vehicles equipped with an automatic transaxle, a Shift to D2 indicator lamp is used to signal when there is a problem within the transaxle controller, contained within the PCM.


CIRCUIT OPERATION
To turn on either indicator lamp, the PCM will supply a ground allowing current to flow through the lamp, turning it "ON".


COMPUTER DIAGNOSTICS
When the diagnostic connector terminals A and B are grounded, the diagnostic trouble codes can be read by counting the number of flashes of the SERVICE ENGINE SOON lamp for PCM/EC (Engine) diagnostic trouble codes or the SHIFT TO D2 lamp on 1991 and 1992 vehicles (or the LOW COOLANT/HOT lamp on 1993 and 1994 vehicles) for PCM/TC (Transmission) trouble codes.
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