12v Drain On Defrost Circuit

T_Oloughlin

New Member
Dec 20, 2015
2
0
1
So I have a 2001 Bullitt with a paracidic drain that I have traced to the rear window defrost circuit. When I pull the rear window defrost relay the drain goes from 12.4v to 0.23v. I have a good set of wiring diagrams (BBBinc.com free .pdf wire diagrams). I have checked to see if the power wires wires were shorting- the only wires with contunuity to ground were the BN/LB(high amp wire from relay to defrost grid-grounded thru the defrost grid and the BK(ground wire from switch). I am getting 12.4v constant at the relay on the BK (high amp from BJB) and BK/WH (low amp from BJB). With the key on the YE/BK gets 0.66v/4.76v(switch off/on). The volt values are with the relay unplugged.

The relay is testing good-no contunuity between the 30 and 87 leads without power and contunuity when power is applied between the 85 and 86 leads.

I have tried a new relay thinking it might cure the drain but it didn't. I am beginning to think the problem lies in the instrument cluster but cannot find any info on the circuitry of it and don't know a resistor from a diode.

Any testing procedures or diagnostic tricks anyone can think of would be much appreciated.

As of right now I leave the relay unpluged unless i plan to use the defrost and then unplug it before I get out of the car. The car is 100% all stock and I plan on keeping it that way.
 
  • Sponsors (?)


I think i have a bad transistor but cant find the datasheet for it. Printed on it is •110 1CB 115
 

Attachments

  • 20151221_171754_Richtone(HDR)-21.jpg
    20151221_171754_Richtone(HDR)-21.jpg
    152.5 KB · Views: 178