A/T - Revised Diagnostic Procedural Charts

File In Section: 7 - Transmission

Bulletin No.: 67-71-63

Date: December, 1996

SERVICE MANUAL UPDATE

Subject:
Section 7A - Automatic Transmission

Models:
1997 Chevrolet and GMC C/K Models
with HYDRA-MATIC 4L8OE Transmission (RPO MT1)

This bulletin updates the 1997 C/K Truck automatic transmission 4L80E diagnosis section. Replace the attached pages in your Service Manual. The updates are as follows:





Component Resistance chart circuit numbers corrected.





Automatic transmission wiring harness assembly 20-way connector, engine side terminals "L" and "P" wire colors corrected.








DTC P0730 Incorrect Gear Ratio (5.7L and 7.4L Gas) steps 5, 6, 7, 8 and the "Values", "Yes", and "No" columns corrected.








DTC P1871 Undefined Gear Ratio (6.5L Diesel Only) steps 5, 6, 7, 8 and 9 the "Values", "Yes", and "No" columns corrected.








DTC P1875 4 Wheel Drive Switch Circuit (6.5L Diesel) and (5.7L and 7.4L Gas) steps 2, 3 and 4 "Action" column corrected.





1-2 shift solenoid valve and 2-3 shift solenoid valve descriptions corrected.





Automatic transmission input speed, output speed sensors descriptions corrected.





Automatic transmission fluid temperature sensor assembly description corrected.