Delta 88 V6-3800 3.8L (1988)
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If both the speedometer and scan tool display the same speed, check for correct tire size and VSS drive gears. If OK, replace vehicle speed sensor.
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If scan tool and speedometer do not display the same speed, go to step 2.
2.
If harness adapter J-33431-10 is available, use it to connect the I/P tester to terminal F (DK GRN) of vehicle speed sensor buffer connector C1
(disconnected). This can be accomplished using the J-35616 connector test adapter key. With ignition switch in "RUN," set the tester controls to
"54 mph," "60 Hz," and "ON."
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Replace speedometer if speedometer does not display 54 mph +/- 2 mph.
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Replace vehicle speed sensor buffer if speedometer displays 54 mph +/- 2 mph.
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If harness adapter J-33431-10 is not available, replace the speedometer. Replace vehicle speed sensor buffer if speedometer is still inaccurate.