Why does my blower, abs and 4x4 on a 99 gmc k 3500 classic cross I sometimes have blower sometimes not kicks out when I put it in four by and my abs and park it light flashes when I turn blower knob!
at first was going to suggest a blower resistor pack, but the heater control might solve your problems~ http://www.ebay.com/itm/like/390269639942?lpid=82
Well I have changed that and the resistor and I wonder if it a short somewhere but I don't know where they cross? Itl b where the four by and blower cross up to the abs
Check voltage at the fuses for these devices, could be your ignition switch has a worn contact in it, an ignition switch has anywhere from 1 to 4 power inputs depending on the vehicle and electrical options, when the key is turned contact is made inside and can transfer power to up to 8 outlet wires again depending on vehicle. Each of those wires feed a handful of accessories. If a contact gets burnt and has limited or no voltage passing through it then all the accessories on that wire wil be effected. Things like the auto daytime running lights run off a relay requiring little voltage to begin with so the will run uninterrupted until something requiring more voltage to run is turned on. I know for an absolute fact that on the early 2000 gm cars their auto daytime running lights, hvac, and heated seats all run off the same wire. The daytime running lights will work until you turn the blower on, except on high because it also runs off a relay. Same with the heated seats, turn them on and the DRLs shut off. If the ignition switch is the issue and the voltage at one of the fuses is less then it will be low on all them. To further the test take a hefty jumper cable from battery positive and run it through the fuse on the power side, check which is which by removing the fuse and testing each side for power. Jumping battery positive to the correct side will make the symptoms disappear, connecting it to the wrong side will pop a fuse. A test light will NOT suffice, it only needs Abbott 1.5 volts to operate, you need actual voltage at the fuses. Let us know what you find. I can post proper procedures for you to repair whatever is broken.
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