* 4L60E (4-speed automatic): This was a very common transmission in this year and model.
* 4L80E (4-speed automatic): More common in heavier-duty models or those with larger engines.
* 4L70E (4-speed automatic): Less common but possible in some configurations.
* Allison 1000 (5-speed automatic): Found in some heavy-duty models.
Troubleshooting any automatic transmission is complex and requires specialized knowledge and tools. It's not something easily explained in a short answer. However, I can give you some general steps and things to look for:
1. Identify the Transmission: First, you absolutely MUST determine the exact transmission in your truck. This information is usually found on a sticker under the hood, on the driver's side doorjamb, or in your owner's manual.
2. Gather Information about the Problem: Describe the problem as specifically as possible. Some common symptoms include:
* Slipping: The transmission feels like it's not engaging properly, or the engine revs high without a corresponding increase in speed.
* Hard Shifts: Abrupt or jarring shifts between gears.
* No Movement: The truck won't move at all.
* Whining Noise: A high-pitched whining sound, often indicating bearing wear.
* Grinding Noise: A grinding sound, usually indicating gear damage.
* Check Engine Light: Note any trouble codes that are stored in the vehicle's computer. You'll need an OBD-II scanner to retrieve these codes.
3. Basic Checks (Do these BEFORE anything else):
* Fluid Level and Condition: Check the transmission fluid level with the engine running and at operating temperature (carefully, it's hot!). Inspect the fluid color and smell. Dark brown, burnt-smelling fluid indicates problems. Low fluid is a serious issue.
* Fluid Leaks: Inspect the transmission pan, lines, and cooler for any leaks.
* Electrical Connections: Check all electrical connections to the transmission, including the solenoid pack and the transmission control module (TCM). Loose or corroded connections can cause problems.
4. More Advanced Troubleshooting (requires experience and specialized tools):
* OBD-II Scan: Retrieve and interpret trouble codes from the vehicle's computer. These codes can often pinpoint the problem.
* Transmission Pressure Tests: Measure the transmission fluid pressure under various conditions. This requires a specialized pressure gauge.
* Line Pressure Testing: Similar to pressure testing, but specifically looks at pressure from the pump to different sections of the transmission
* Internal Inspection: Often requires removal of the transmission and disassembly for internal inspection. This is best left to a professional transmission shop.
Important Note: Troubleshooting a transmission is a complex process. If you're not comfortable performing these checks or if you lack the necessary tools and expertise, you should take your vehicle to a qualified mechanic or transmission specialist. Attempting major repairs yourself without the proper knowledge could lead to further damage and costly repairs. Improperly handling transmission fluid can also be dangerous.
