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Discussion Starter #1
Please, anyone try help me locate the relay for rear defogger.

Whenever the rear defogger is working and when the switch is pressed, I heard a click sound under the steering column and the deffogging system works. But, now no such sound when switch is pressed and deffogging not working. Front defogger is fine.

Also, I removed all panel under steering cover still couldn't locate it.
 

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Your probably sick of me saying this :) but I'm not familiar with the i20.
I do know there are a couple of relays on the rear of the dashboard fusebox though. Maybe one of those is for the rear defogger.
 

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Discussion Starter #3
Your probably sick of me saying this <img src="http://www.hyundai-forums.com/images/smilies/smile.gif" border="0" alt="" title="Smile" class="inlineimg" /> but I'm not familiar with the i20.
I do know there are a couple of relays on the rear of the dashboard fusebox though. Maybe one of those is for the rear defogger.
Yes I took off the 2 relays and tested too the relays they are working, also I started the car but front defogger is still working but rear is same as before ie still doesn't work.

Sometimes it's working sometimes not!!!!!!
 

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What would be the cause for deffogging not working!!!!?????
The defogger relay will almost certainly be controlled by the BCM. You've been messing with the BCM recently when working on the door locking so I'd make sure all the connections are plugged in properly and none of the wires have backed out of the connectors.

The defogger is a heavy electrical consumer so it's control circuit is designed to prevent it from switching on if there is a problem with the alternator/charging system. Does the battery warning light illuminate when you turn the ignition on, and switch off once the engine is running?
 

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Discussion Starter #6
The defogger relay will almost certainly be controlled by the BCM. You've been messing with the BCM recently when working on the door locking so I'd make sure all the connections are plugged in properly and none of the wires have backed out of the connectors.

The defogger is a heavy electrical consumer so it's control circuit is designed to prevent it from switching on if there is a problem with the alternator/charging system. Does the battery warning light illuminate when you turn the ignition on, and switch off once the engine is running?
The issue was there before starting installation of remote locking system.

All connections were secured properly.

Yes battery comes on at key on position, and off when engine running.
 

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You'd either need a wiring diagram or a Hyundai specific scan tool to diagnose the issue, so we're kinda stuck since we don't have neither.
 

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Discussion Starter #8
According to my experience, I feel that it used to come on when outside temperatures is high and refused to come on when temperatures is low especially in early morning.
 

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Discussion Starter #9 (Edited)
Some wiring harness found on internet.... hopefully it may relate to the present car we are dealing with.😂
 

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According to the diagram the defogger relay coil is powered by the interior light fuse. Is your interior light working?
 

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The next step would be to ID the relay control wire either at the BCM or where it enters the fusebox and ground it via your test light to see if the relay switches on.

 

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Discussion Starter #13
I have to probe the defogger wire on BCM input connector with engine starting, right???? If so, no issues while probing with engine starting???!!
 

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The defogger wire will be on the output connector of the BCM. It's an output that is used to control the relay.
You don't need to have the engine running for this test, and according to the diagram the relay power supplies both come directly from the battery so you shouldn't even need the ignition switched on.
 

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Discussion Starter #15
Woooow nice to hear that ..
It would be a tidy and simple job to Id the wire.....

Also I guess the wire is negatively trigger right??
 

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Discussion Starter #17 (Edited)
Yes, with output BCM connector detached and tested, the relay clicks and test light glows but the defogger led indicator doesn't glow, it only come on when the key is at only ON POSITION..and ..all working...!!!

The main issue now is that "the relay is not activated when the rear defogger switch is pressed and also led indicator doesn't glow in the normal connections".


With output connector reattached back.....
when engine running, and front defogger is pressed, then led comes on, relay clicks, alternator spinning, yes, front deffogging system is ok.

Now, still connector attached, front deffogging is manually off and alternator stops spinning. This is fine till here.

Now, still connector attached, engine running, and rear defogger is pressed, no led comes on, no relay sound, no alternator spins, and eventually rear defogging system is not working.

The rear defogger doesn't even work also when front deffogging system is being turn on!!!!!

In all above tests, battery warning comes on when key at ON position and off when engine running. So, charging system as well as alternator are working fine and other signals also off too ie normal. Please correct if I'm wrong.

Now, next step????
 

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Discussion Starter #18 (Edited)
Once again viola......

I disconnect and reconnect the 2 connectors of the BCM and tested again, yes, all working fine ........!!!!!😇😇😇😇😇

One dauds...is the alternator supposed to be not spinning when the rear defogger is switching on???

But it spins when front defogger is pressed!!!!
 

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One dauds...is the alternator supposed to be not spinning when the rear defogger is switching on???

But it spins when front defogger is pressed!!!!
The alternator is driven by the engine, so it spins whenever the engine is running regardless of whether the defogger is on or not.
 
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