A scanner is not necessary. All you need is a volt meter with a needle. If you look in the manual section> over 216 manuals> look for the Haynes Manual. It covers your MM truck. In there is a step by step with pictures on what pins to use. All you do is count the swings of the needle and look them up. The EGR light comes on every 50,000 mile or so and needs to be reset. It's behind the speedo a tiny switch that you flip.