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Ivan, ASE Certified Master Technician
Category: Car
Satisfied Customers: 4871
Experience:  ASE Master Tech w/ 20+ years in the field. Self employed for 9 years. Member of AUTOLAB radio show.
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1999 pontiac grand prix: only high speed..running lights..disconnect

Customer Question

I have a 1999 pontiac grand prix. I have only high speed on the blower. Also when i put the blower on the day time running lights go off.If i disconnect the resister, the lights are uneffected, then ok. I checked the power at the resister 12 volts is there.I also checked continuity from the switch to the resistor all wires have continuity.I am thinking that i am getting some kind of feedback through the day time running lights due to a loss of a ground. Also every wire to resister seems to have 12 volts.
Submitted: 8 years ago.
Category: Car
Expert:  Ivan replied 8 years ago.

HelloCustomer Here is the diagram for your blower circuit. You will have 12 volts before the resistor, since the resister reduces the voltage for your lower speeds. If the resitor fails, you will only have high speed, since that speed bypasses the resistor all together. There is only on ground G200 that controls this whole circuit. Check for your signal into the relay from the resistor. If you have no power at it, the resistor is bad. Fix that first and see if you lighting issue goes away. Let me know if you need any further help as you proceed.


Your JA Expert,


Customer: replied 8 years ago.
I need to know where the relay and the g200 circuit are located in the car. In a relay box or under the dash?
Expert:  Ivan replied 8 years ago.

Here is what I found for the blower relay.



The Blower Motor Relay is located in the Blower Resistor Assembly and cannot be serviced separately. The Blower Resistor Assembly is located behind the right side of the Instrument Panel (IP) , in the right side of the heater-A/C control module.


And here is the ground location.



Right side of the IP cross beam, behind the fuse block


Customer: replied 8 years ago.
I checked the ground its ok.I have already replaced The resister new and have same problem. When i turn the blower switch from off to 1 and then touch the hot cold knob it effects day time lights . blower runs onhigh when i touch temp knob. When i repeat from off turn to 1 nothing runs then i turn to 5 still nothing as soon as i touch temp knob 5comes on which is high.
Expert:  Ivan replied 8 years ago.

Here is a diagram of the Daytime running lights. Look for your common points. May be unplug the daytime running light module and see how the fan responds.graphic


Here is the location for that module and it is in the same vicinity. I think you have 2 wires touching each other in that area.