I am trying to help my son fix his car a bit. 2000 Grand Am and the blinkers work when it is under 25 degrees. Cold all nite,jump in they work fine. Heater warms up car inside and they quit. When it is over 25 degrees, outside they dont work. Where do you start looking for that problem solution???
You need a multimeter and a factory wiring diagrams manual which is part of the factory service manuals set for your vehicle. Order from dealer or helminc.com.
Then follow the troubleshooting instructions.
You need this because all the wiring is wrapped in harnesses and it is impossible to trace wires and see where they go. These books tell you which connectors are where specifically, which terminals are what, what wire color is for what, where various components like relays are located, etc.