# Load reduction Relay



## montmil (Jul 8, 2006)

Tried _Search_ but no joy, so... What function does the Load Reduction Relay serve? With all the fuses and other relays on board, what has to happen to trigger this particular relay?


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## briano1234 (Feb 20, 2004)

*Re: Load reduction Relay (montmil)*

The load reduction relay is to reduce the load (current) off the primary path to a different path. 
It is usually found in the lighting circuits that run the head lights where heavy demand for current is needed.


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## kamzcab86 (Feb 14, 2002)

*Re: Load reduction Relay (briano1234)*


_Quote, originally posted by *briano1234* »_The load reduction relay is to reduce the load (current) off the primary path to a different path. 
It is usually found in the lighting circuits that run the head lights where heavy demand for current is needed.

http://****************.com/smile/emthup.gif It's job is to basically cut power to all major accessories during start-ups.


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## tolusina (Oct 19, 2004)

*FV-QR*

"X" on the ignition switch is on, or 'hot' when the key is in the on position, X switches off while cranking.
The load reduction relay and the headlights (no taillights or markers on this circuit) are both powered by "X" on the ignition switch, wipers, HVAC fan and rear defogger are powered off the load reduction relay.
Normally, if the load reduction relay is faulty or removed, wipers, HVAC fan and rear defogger will fail to operate, the headlights will still operate normally.

If "X" on the ignition switch fails, headlights and the load reduction relay (including wipers, HVAC fan and rear defogger) will all be inoperative.

The idea behind the whole "X" circuit is to switch off high current drawing devices while cranking.


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## montmil (Jul 8, 2006)

*Re: FV-QR (tolusina)*


_Quote, originally posted by *tolusina* »_"X" on the ignition switch is on, or 'hot' when the key is in the on position, X switches off while cranking... 

Thanks, Ron. Lots of good info and written for folks whom do not have a degree in electrical engineering. http://****************.com/smile/emthup.gif


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## Brodiekagstar (Apr 14, 2004)

Bringing this back hoping for a little help. Does anyone know why my radio or interior lights only sometimes dim when starting. I replaced the load reduction relay it didn't help. I am trying to figure this out and see if for some reason this could back feed and fry a fuel relay on the ignition circuit. 
It's a mkiv 1.8 wagon. It's quite a different car but any help is appreciated.


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## briano1234 (Feb 20, 2004)

Well I would change the ground wires on my car, that is battery to frame, and frame to engine/tranny. 

A bad ground will cause the kinds of things that you mention to happen.


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## tolusina (Oct 19, 2004)

Brodiekagstar said:


> ......... Does anyone know why my radio or interior lights only sometimes dim when starting. .....
> 
> .......It's a mkiv 1.8 wagon. It's quite a different car but any help is appreciated.


 Lights dimming while cranking is normal.
The high current draw of the starter motor pulls down the available battery voltage. You can verify this for yourself by connecting a voltmeter directly to the battery terminals, observe the voltage drop while cranking.
Conversely, once the charging system kicks in and system voltage rises, lights will be brighter than when operating off of battery voltage only.
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I think, but am not certain, that A4 chassis cars use the same load reduction circuit as earlier cars and if so, it only acts on the headlights, wipers, HVAC and rear defogger as described above. Not related to the symptoms you've described.
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And, what Brian posted, funky old ground cables cause all sorts of unpredictable electrical issues, as does the main battery power cable.








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## Brodiekagstar (Apr 14, 2004)

The radio is def on the x circuit controlled by the load reduction relay. The radio turns off sometimes, flickers off sometimes and other just stays on. Same with the dash lights they just dim where as the head lights turn off. The grounds inside are fine. I checked the interior grounds to the chassis and battery and got continuity and the mechanic checked them too.


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## Brodiekagstar (Apr 14, 2004)

It's a California mk4 things don't really get funky or deteriorate much.


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## briano1234 (Feb 20, 2004)

Want to bet?


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## 4door_mk3 (Mar 16, 2011)

im getting some sort of the same issue. When i turn my car to acc. to like start my car i loose everything in my cluster such as the mileage and the clock. i have replaced my ignition switch thinking that was the problem but still have issue. so i called a vw garage and they said it could be the load reduction relay. Any chance that it could be my problem?


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