Here's a general outline of the process. Specific details may vary slightly depending on your exact transmission type (e.g., 700R4, TH350, etc.). You'll need to consult a repair manual specific to your truck's transmission for precise instructions and diagrams.
1. Identify the Cable: Locate the transmission shift cable where it connects to the transmission lever and the linkage on the steering column.
2. Access the Adjustment: This usually involves accessing the cable's connection points. You may need to remove parts like the air cleaner, battery, or other components to gain better access.
3. Loosen the Adjusting Mechanism: There's typically a locking nut and an adjusting nut (or a similar mechanism) on the cable at either the transmission or the linkage. Loosen the locking nut to allow adjustment.
4. Adjust the Cable: This is the most crucial step and where having a repair manual is vital. The adjustment usually involves moving the cable slightly at a time, then checking the gear selection at the shifter. You want the shifter to accurately align with the actual gear selected by the transmission.
* General Approach: You'll typically adjust the cable so that the gears engage smoothly and correctly. Start by making small adjustments (1/8 to 1/4 turn at a time). Shift the transmission through all the gears, checking for smooth engagement and correct selection.
* Finding the "Sweet Spot": This involves a process of trial and error. You may need to move the cable slightly, then test the shifting, adjust again, and re-test until the shifting is precise.
5. Tighten the Locking Nut: Once you've achieved correct shifting, tighten the locking nut to secure the adjustment.
6. Test Drive: Test drive the vehicle and shift through all the gears to ensure the adjustment is correct. If the shifting is still not smooth or accurate, you may need to re-adjust the cable.
Important Considerations:
* Repair Manual: A factory service manual for your specific 1990 Chevy Silverado is crucial. It will have diagrams and precise instructions specific to your truck's transmission type and model.
* Transmission Type: The exact adjustment procedure will depend on the type of automatic transmission your truck has.
* Safety: Always disconnect the negative battery cable before starting any work on your vehicle's electrical system.
Again, if you're not comfortable working on your vehicle, it's best to have a qualified mechanic perform the adjustment. Incorrect adjustment can cause serious damage to your transmission.
