parasitic draw with relay and resistor
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URL: https://www.the12volt.com/installbay/forum_posts.asp?tid=128188
Printed Date: May 08, 2025 at 9:30 PM
Topic: parasitic draw with relay and resistor
Posted By: wishboneattack
Subject: parasitic draw with relay and resistor
Date Posted: August 09, 2011 at 5:32 PM
I got a question:
I have a car with a parasitic draw at the aftermarket stereos car harness module. If I unplug the module(gm21sr) the draw goes away. The module has been replaced 3 times and the draw is still there. Scosche doesn't seem to know how to fix it.
So my thought was to put in a relay. If I use a bosche 5 pin wired as described below, would this stop the draw, and allow the module to retain memory?
Pin 85 to ground
Pin 86 to ignition +12
Pin 30 to +12 constant
Pin 87A to module +12 with a 1.5K resistor in series. (between module and relay)
Pin 87 to module +12 (after resistor)
See image below
By my calculation current passed while the car is off would be .008A. The draw I have now is .144A at the module. Overall the car has .156A. This would reduce my draw to an acceptable level .02A.
Any thoughts on this would be awesome. I am not willing to get another brand of harness. I tried that and the modules quit functioning. Meaning I loose Onstar, door chimes, and turn signal clicks over a short period of time.
Sorry it is a crude markup from MS Word
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I may be lost but I am making good time.
I have a car with a parasitic draw at the aftermarket stereos car harness module. If I unplug the module(gm21sr) the draw goes away. The module has been replaced 3 times and the draw is still there. Scosche doesn't seem to know how to fix it.
So my thought was to put in a relay. If I use a bosche 5 pin wired as described below, would this stop the draw, and allow the module to retain memory?
Pin 85 to ground
Pin 86 to ignition +12
Pin 30 to +12 constant
Pin 87A to module +12 with a 1.5K resistor in series. (between module and relay)
Pin 87 to module +12 (after resistor)
See image below
By my calculation current passed while the car is off would be .008A. The draw I have now is .144A at the module. Overall the car has .156A. This would reduce my draw to an acceptable level .02A.
Any thoughts on this would be awesome. I am not willing to get another brand of harness. I tried that and the modules quit functioning. Meaning I loose Onstar, door chimes, and turn signal clicks over a short period of time.
Sorry it is a crude markup from MS Word
-------------
I may be lost but I am making good time.
Replies:
Posted By: KPierson
Date Posted: August 10, 2011 at 5:40 AM
Posted By: oldspark
Date Posted: August 10, 2011 at 11:04 AM