back-up lights

07-28-2009, 11:17 AM

I have a 94 Pontiac Formula and cant get the backup lights to work. With any one of the b-u lights in the harness i get no voltage. when both lights removed i have 12 volts in the harness. switched these bulbs to other car and worked fine. checked switch on manual trans=fine. checked ground=fine. I'm lost. If anyone knows pls help. these are supposedly the correct 1156 bulbs.



07-28-2009, 11:34 AM
You have a corroded/almost broken/poor contact wire somewhere. When there is no load/open circuit on the wire you see twelve volts. as soon as the bulb is installed the circuit is closed and the added resistance of the corrosion before the load (bulb)will drop the current to nothing. With everything plugged in and the bulbs installed back probe the wiring until you find twelve volts. The problem is in between where you found 12 volts and where you had no voltage.

07-29-2009, 07:38 AM
Thanks Airjer-

I will try what you suggested.

Does anyone know if in some cases the 1156 bulb is NOT interchangeable with the 1141? parts store says 1141 but x-reference says 1156 will work. I'm almost positive 1156 was what was in car when lights worked.


07-29-2009, 10:22 AM
My refference says 1141 as well. The only difference I can see is the wattage of the bulb. The 1141 is ruffly 18watts and the 1156 is ruffly 24.

08-05-2009, 01:43 PM
Thanks Airjer for the good help!

Found my corrosion/continuity problem at the switch on the transmission. Now I have back-up lights! :grinyes:

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