What does the Battery Saver Relay do? - Ranger-Forums - The Ultimate Ford Ranger Resource


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Old 09-15-2010
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What does the Battery Saver Relay do?

When my 2002 Ranger is parked and turned off --if I pull fuse #26 -- I hear a click under the dash to the right of the gas pedal. It is my feeling that NO relays should get power when the vehicle is shut off. Relays suck power like a light bulb does. One of the things that fuse # 26 powers is the Battery Saver Relay. I wonder what this relay is supposed to do and where it is mounted. I would appreciate any input.
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Old 09-15-2010
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The Battery Saver Relay is controlled by the Generic Electronic Module. It depowers any courtesy lights that are accidentally left on after about a 10 minute delay with the key turned off. So the relay coil is only powered for those ten minutes after key shutoff. The BSR is in Aux Relay Box #1, a rectangular black box with a snap off cover, up under the dash to the right of the steering column.
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Old 09-16-2010
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"rwensing" --Thank you very much for the explanation on the relay. I am questioning the current draw on my vehicle while it is turned off. I now understand that the relay will de-activate after about ten minutes and will extinquish power to the dome light etc. , I have been doing my amperage readings without waiting for the relay to de-activate.
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Old 09-16-2010
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Clarification:

The countdown timer for the courtesy lights does start after key off. However, it also resets and starts again whenever courtesy light circuit operation is commanded by the GEM. Activity at the door switch or Remote Keyless Entry tells the GEM to repower the Battery Saver Relay so that you can always have 10 minutes of courtesy lights on entry before starting the engine.

So it's possible to have the relay engaged for more than 10 total minutes if there is activity that triggers the GEM and resets the timer (for example, opening the door during the 10 minute countdown).

BTW, the 10 minute nominal figure is just an estimate. I've never timed it and it may vary somewhat from year to year.
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Old 09-16-2010
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Quote:
Originally Posted by rwenzing View Post
Clarification:

The countdown timer for the courtesy lights does start after key off. However, it also resets and starts again whenever courtesy light circuit operation is commanded by the GEM. Activity at the door switch or Remote Keyless Entry tells the GEM to repower the Battery Saver Relay so that you can always have 10 minutes of courtesy lights on entry before starting the engine.

So it's possible to have the relay engaged for more than 10 total minutes if there is activity that triggers the GEM and resets the timer (for example, opening the door during the 10 minute countdown).

BTW, the 10 minute nominal figure is just an estimate. I've never timed it and it may vary somewhat from year to year.

I think that it is actually 30 minutes. When I designed my door transistor controlled puddle lamps circuit I had a problem where they would work correctly, but after while one of them would dimly come on. I timed it and could exactly repeat it in 30 minutes. It dropped the voltage from 12V, to 3 (or 5, I can't remember). I was able to solve this problem by adding a component to my circuitry (trade secret) but this is how I learned about it.

Last edited by Jp7; 09-16-2010 at 07:08 AM.
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Old 09-16-2010
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on my 08 i also find that if i leave the doors open if i'm working on something, the BSR turns off the dome light after a short period of time 3-5 minutes. the door is still open at this point but my lights have turned off.
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Old 09-26-2010
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My testing shows for 40 minutes the BSR keeps power to the interior light circuit after closing the door.
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