03 Blazer Key FOB Horn Lighting Issue??

Lawgiver · December 13, 2019

Hello Everyone,

Thought I would post here before finally throwing in the towel and going to the dealer. I have an 03 ZR2 Blazer that I store during the winter months. It has been in storage since the beginning of Nov. I needed to get something out of the truck this evening and used the key FOB to unlock the truck. No problem. Got what I needed and used the FOB to lock the truck. Normally, the horn sounds briefly as well as the parking lights/tail lights flash. This time the horn sounded continuously and would not shut off. This wasn't the factory security system activating. The headlights were not flashing etc. Just one continuous horn blast. I popped the hood and pulled the fuse for the horn.

I honestly thought the relay was stuck in the open position. Went to get a shop light and a few tools when I noticed the tail lights on. Nothing else was on except the tail lights. Swapped out the horn relay with a known good one and still the horn would not shut off. I cycled the key FOB several times/panic button minus the fuse/horn and everything worked as it should. However, the tail lights were still on. I discovered the only way to get the tail lights off was to pull the relay for the horn.

Attempted to search the forums without any luck. Does anyone know if there is a separate relay used by the wireless system??? I am at a loss and any help would be appreciated.

Thanks

NOTE: When I say it is just the tail lights on, that's it. Neither the dash lights or parking lights are on. It is as if there is only power to the tail lights.

Justin101714 · December 18, 2019

Hello Everyone,

Thought I would post here before finally throwing in the towel and going to the dealer. I have an 03 ZR2 Blazer that I store during the winter months. It has been in storage since the beginning of Nov. I needed to get something out of the truck this evening and used the key FOB to unlock the truck. No problem. Got what I needed and used the FOB to lock the truck. Normally, the horn sounds briefly as well as the parking lights/tail lights flash. This time the horn sounded continuously and would not shut off. This wasn't the factory security system activating. The headlights were not flashing etc. Just one continuous horn blast. I popped the hood and pulled the fuse for the horn.

I honestly thought the relay was stuck in the open position. Went to get a shop light and a few tools when I noticed the tail lights on. Nothing else was on except the tail lights. Swapped out the horn relay with a known good one and still the horn would not shut off. I cycled the key FOB several times/panic button minus the fuse/horn and everything worked as it should. However, the tail lights were still on. I discovered the only way to get the tail lights off was to pull the relay for the horn.

Attempted to search the forums without any luck. Does anyone know if there is a separate relay used by the wireless system??? I am at a loss and any help would be appreciated.

Thanks

NOTE: When I say it is just the tail lights on, that's it. Neither the dash lights or parking lights are on. It is as if there is only power to the tail lights.

Okay, each tail lamp assembly tail lights run on separate circuits. The odds of both being shorted in the wiring is pretty slim, they originate in the underhood fuse block with the horn. I suspect bad underhood fuse block. If you remove the horn fuse do the lights go out? I know you removing the relay works.

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Lawgiver · December 18, 2019

1 hour ago, Justin101714 said:

Okay, each tail lamp assembly tail lights run on separate circuits. The odds of both being shorted in the wiring is pretty slim, they originate in the underhood fuse block with the horn. I suspect bad underhood fuse block. If you remove the horn fuse do the lights go out? I know you removing the relay works.

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Hi Justin,

Thanks for the reply. The lights are still on with the horn fuse in place. Originally, I was just going to pull the fuse and leave the relay in place to stop the horn from sounding. I did that and was walking away from the truck when I noticed the tail lights on. The only way to get the lights out was to pull the relay. So, I left the fuse in place and pulled the relay. I might add with the relay out, the lights function normally ie. turn signals, tail lights activating with the headlight switch etc.

One thing I can check is if the lights are on with both the relay and fuse in place. I suspect "yes" but I will double check. It will have to wait until the AM. It is just after 2 in the morning here and with the horn sounding, I will give my neighbors a break. Thanks for your time.

Rob