2004 Dodge Ram 2500 Pickup Owner's Manual - Page 326
2004 Dodge Ram 2500 Pickup Manual
Page 326 highlights
326 MAINTAINING YOUR VEHICLE b. The MIL light will remain fully illuminated until the first engine crank or the key is turned off. This means that your vehicle's OBD system is ready and you can proceed to the I/M station. If your OBD system is not ready, you should see your dealer or repair facility. If your vehicle was recently serviced or had a battery failure or replacement, you may need to do nothing more than drive your vehicle as you normally would in order for your OBD system to update. A recheck with the above test routine may then indicate that the system is now ready. Regardless of whether your vehicle's OBD system is ready or not ready, if the MIL symbol is illuminated during normal vehicle operation, you should have your vehicle serviced before going to the I/M station. The I/M station can fail your vehicle because the MIL symbol is on with the engine running. DEALER SERVICE Your dealer has the qualified service personnel, special tools and equipment to perform all service operations in an expert manner. Service manuals are available which include detailed service information for your vehicle. Refer to these manuals before attempting any procedure yourself. NOTE: Intentional tampering with emissions control systems can result in civil penalties being assessed against you.