Understanding the OBD2 (On-Board Diagnostics II) system in your 1999 Chevrolet Silverado is crucial for effective vehicle maintenance and repair. The OBD2 port acts as the gateway to your truck’s computer, allowing mechanics and DIY enthusiasts to diagnose issues, read trouble codes, and ensure optimal performance. This article provides a detailed look at the 1999 Silverado Obd2 Pinout, helping you understand each pin’s function and how it relates to diagnosing your vehicle.
Decoding the OBD2 Port on Your 1999 Silverado
The OBD2 port, standardized across most vehicles in the late 1990s, is typically located under the dashboard on the driver’s side of your 1999 Silverado. This 16-pin connector provides access to various communication protocols and power sources essential for diagnostic tools to interface with your truck’s computer systems. For 1999 GM vehicles like the Silverado, the primary communication protocol used is J1850 VPW (Variable Pulse Width Modulation). While the OBD2 standard aims for uniformity, understanding the specific pinout for your 1999 Silverado is vital as pin assignments can sometimes vary slightly depending on the model and specific vehicle options.
1999 Silverado OBD2 Pinout Diagram and Pin Functions
Here’s a breakdown of the 1999 Chevy Silverado OBD2 pinout, detailing the function of each pin. This pinout is based on the standard for pre-2000 GM vehicles using the J1850 VPW protocol, but always refer to your vehicle’s repair manual for the most accurate information.
| Pin Number | Pin Name | Function |
|---|---|---|
| 1 | Low Speed GMLAN | Low speed GMLAN serial data for various modules including amplifier, radio, instrument panel cluster, body control module, and more. |
| 2 | J1708 | SAE J1708 Serial Data (Typically for trucks) |
| 3 | PTLAN (+) | High-speed hybrid GMLAN serial data bus (+) terminal (Hybrid models only) |
| 4 | Chassis GND | Chassis Ground |
| 5 | Signal GND | Signal Ground |
| 6 | HS-CAN (+) | High-Speed GMLAN Serial Data Bus +. Used for communication between critical modules like BCM, ECM, TCM, and EBCM. |
| 7 | KW200/J1708 A | Keyword 2000 Serial Data (on some models) / SAE J1708 Serial Data A (Trucks only) |
| 8 | CCM Diagnostic Enable | Central Control Module Diagnosis Enable (Specific to some Holden models, may not be applicable to Silverado) |
| 9 | SIR Serial Data | Supplemental Inflatable Restraint (SIR) Serial Data |
| 11 | PTLAN (-) | High-speed hybrid GMLAN serial data bus (-) terminal (Hybrid models only) |
| 12 | Diagnostic Signal (ABS)/(15,000 GVW Only) | Diagnostic Signal for ABS (Anti-lock Braking System), potentially also for vehicles with 15,000 GVW (Gross Vehicle Weight). |
| 13 | Diagnostic Signal-Transfer Case Control Module | Diagnostic Signal specifically for the Transfer Case Control Module. |
| 14 | HS-CAN (-) | High Speed GMLAN Serial Data Bus -. Complementary signal to pin 6 for high-speed communication. |
| 15 | J1708 B | SAE J1708 Serial Data B (Trucks only) |
| 16 | Battery+ | Battery Positive Voltage. Provides power to the OBD2 scanner and potentially other diagnostic tools. |
It’s important to note that Pin 2 is designated for Serial Data Signal – Class B in pre-2000 OBD2 connectors, which aligns with the J1850 VPW protocol used in the 1999 Silverado.
Why is the 1999 Silverado OBD2 Pinout Important for Diagnostics?
Knowing the 1999 Silverado OBD2 pinout is essential for several reasons:
- Accurate Diagnostics: Pinouts ensure you are connecting your diagnostic tools to the correct pins for communication. Incorrect connections can lead to inaccurate readings or even damage to your vehicle’s computer system or the diagnostic tool.
- Troubleshooting Communication Issues: If you are experiencing problems connecting your OBD2 scanner, understanding the pinout helps you verify the integrity of the connection. You can check for voltage at the Battery+ pin (Pin 16) and ground at the Ground pins (Pin 4 and 5) to ensure the port is properly powered.
- Advanced Diagnostics and Repair: For more complex diagnostics or custom modifications, knowing the pinout allows experienced technicians to directly access specific circuits for testing and repair.
- Emissions Testing: OBD2 compliance is crucial for emissions testing. Understanding the pinout indirectly helps ensure your vehicle can be properly tested and meet emissions standards.
Using an OBD2 Scanner with Your 1999 Silverado
Diagnosing your 1999 Silverado with an OBD2 scanner is a straightforward process:
- Locate the OBD2 port: It’s typically under the dashboard on the driver’s side.
- Connect the Scanner: Plug your OBD2 scanner into the port.
- Turn the Ignition ON: Turn your Silverado’s ignition to the “ON” position without starting the engine. This powers up the vehicle’s computer systems.
- Follow Scanner Instructions: Navigate your OBD2 scanner’s menu to initiate a vehicle scan, read trouble codes, or access live data.
By understanding the 1999 Silverado OBD2 pinout and how to use an OBD2 scanner, you are better equipped to maintain your vehicle, diagnose potential problems, and ensure its long-term reliability. Remember to always consult your Silverado’s service manual for specific diagnostic procedures and pinout confirmations.
