Pontiac Repair: 2002 Grand Prix Electrical Problems, daytime running lights, fuse block

Question
My automatic daytime running lights turn off the moment I turn on my heater fan, and the day time running lamps will only turn back on if the heater is off and I turn on the regular lights and turn them off again. This is happening intermittently which is frustrating. I noticed that someone else mentioned on another forum a possible need to replace the switch/harness, what is this, and where is it found on the vehicle? Any other suggestions?

Thanks in advance.

Dan M.

Answer
Hey Dan:

without seeing it it's hard to say what the issue here is but it's either a power feed or a ground wire issue. these cars were noted for ignition switch failures pretty often but they would have things cut out when you turn on the turn signals and the PRNDL lamps on the speedo would cut out really wierd stuff like that. I have seen the headlamp/blower cenario you mentioned here be from an ignition switch but I wouldn't condem  it with out verifying it first. when it happens or if you can get it to happen check the HVAC fuse in the fuse block with a volt meter and see what kind of battery voltage is present on the fan If it's less then battery voltage by say .50 Volt I would suspect an ignition switch.  They also have ground wire issues at the frame rail near the battery that the ground connection would corrode and that is the ground for all the stuff on the chasis. lastly take a look at the battery cables at the battery. the batteries on these cars would leak acid and cause a corrosion/bad connection primarily on the (+) cable. Good luck :)