Electrical Light issues

Zach Dugan

New Member
Nov 30, 2016
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Hi everybody,
I have a 1999 mustang 4.6 ok so i have been having issues with my lights no dash lights or parking lights taillight i have checked all fuses and also replace the head light switch with two new ones and a used one out of my other mustang witch does work the new switches work on my other mustang as well i can get the lights to come on if the switch is in the perfect spot but the head lights go out then. Im at a loss. Any Ideas???
Thanks
 
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wmburns

SN Certified Technician
Aug 14, 2009
5,761
493
164
Houston Texas
First check for always on power at fuse F2.19 and F1.10. Confirm power in and out (both sides of the fuse). Likely fuse F1.10 is good since the head lights work but best to check to be through. If possible use a test light that will "load" the circuit.

Now at the head light switch, confirm there is +12 volts at the R1 (wire color BN) with the switch in the "park" position.

IF there's no power at the BN wire, I would inspect the head light switch connector for signs of heat damage. Why? Because frequently when the head light switch fails by over heating the heat is also transmitted to the connector. This heat will distort the plastic as well as loosen the metal terminals making for a poor electrical connection.

1999-2004 MY fuse panel schedule:

IMO the reason WHY you are seeing the "strange issue" between settings is because you are forcing the switch to be between settings and this is allowing the headlight portion of the switch to "back feed" the parking lights. This is not the usual setting for the parking light switch but it's normal (I have created the same situation myself).
 
Last edited:

wmburns

SN Certified Technician
Aug 14, 2009
5,761
493
164
Houston Texas
I’m not very good with electrical and it’s terms what is f2.19
Did you READ the information in the links provided? Because I have to believe if you did you would see what F1 and F2 mean.

Cut/paste right from the information provided:

F1=BJB=Battery Junction Box; engine bay
F2=CJB=Central Junction Box; Driver's kick panel

Sooooooooooooooooo F2.19 would be fuse number #19 in the CJB.
 

Zach Dugan

New Member
Nov 30, 2016
13
0
1
25
ok so r1 dose not have any power in any position I checked both fuse and they are fine replaced f2.19 just to be sure. the wire connector does look a bit beat up and discolored
 

Zach Dugan

New Member
Nov 30, 2016
13
0
1
25
First check for always on power at fuse F2.19 and F1.10. Confirm power in and out (both sides of the fuse). Likely fuse F1.10 is good since the head lights work but best to check to be through. If possible use a test light that will "load" the circuit.

Now at the head light switch, confirm there is +12 volts at the R1 (wire color BN) with the switch in the "park" position.

IF there's no power at the BN wire, I would inspect the head light switch connector for signs of heat damage. Why? Because frequently when the head light switch fails by over heating the heat is also transmitted to the connector. This heat will distort the plastic as well as loosen the metal terminals making for a poor electrical connection.

1999-2004 MY fuse panel schedule:

IMO the reason WHY you are seeing the "strange issue" between settings is because you are forcing the switch to be between settings and this is allowing the headlight portion of the switch to "back feed" the parking lights. This is not the usual setting for the parking light switch but it's normal (I have created the same situation myself).
wmburns i spliced in a new connector that did not work. I went out and bought a test light I did not have one i have been using a multi meter i did notice the f1.10 was in fact no good, I put a new fuse in all is working!!!! yay I thank you so so much for your help. The guy i bought the car from had put in an aftermarket alarm in and spliced a bubch of wires in on the harness so at least I got to get rid of that bs :poo:. Now i have one more question maybe you might be able to help with. any time i let the car set for a few days the battery is dead brand new battery alternator tested good after letting the car set for 30 min and i do a draw test it is reading 0.38 mA