AM/FM concerns

Caleb Technician Mishawaka, Indiana Posted   Latest   Edited  
Question
Pico Technology
Trained By Techs
Electrical
Infotainment
2014 Toyota Corolla S 1.8L (2ZR-FE) 6-spd
Poor Am/Fm Reception With Headlights On

Hey guys have an interesting one here. I am at the end of my knowledge of tests I can run to nail this one. This car was in our body shop Dec. 2018. It was hit lightly in the front. The front fascia was replaced along with a piece of radiator support. Now the guy just brought it back saying that when he turns the headlights on the AM/FM reception gets static. He claims it has been happening since the body work. I have no idea if this is true or not. The AM/FM antenna is actually similar to a defrost grid. It is mounted in the top 6 inches of the rear window glass. It has a giant roof rack installed on it that was hanging over the back window. I removed the roof rack with no change in the symptoms. Its not constant static. Its very short like 1-2 second bursts with no real pattern. I have unplugged the antenna at the rear window grid and connected a wire to a conventional whip style antenna and duct taped it too the roof rack bracket with only minimal help in the static. I have pulled the headlamp relay which powers all 4 headlight bulbs while I have the headlight switch on and the problem disappears. This tells me the problem is isolated only to the headlight bulbs and involved circuitry. The switch and control side is not the issue. The headlights are bright and never flicker. All the headlight bulb grounds tested loaded and dynamically to neg battery post have less than 150mv drop. I also checked the AC ripple with the headlights on/car running and its between 200-300mv. I have attached screenshots and PICO file of the ripple. I cleaned the headlight grounds which are under both headlight assemblies with no change. I know the v drop readings gave me no reason too clean the grounds but I didnt want to get caught with my pants down. I also cleaned some battery terminal corrosion. Thanks for any help guys. This screenshot is with lowpass filtering activated.

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Dustin Technical Support Specialist
Escondido, California
Dustin Default
 

First Question is , are both Frequency bands having issues? AM and FM ?

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

So I went and double checked. It seems to be FM only Dustin. Also forgot to mention that Bluetooth audio works great.

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Dustin Technical Support Specialist
Escondido, California
Dustin Default
 

What type of headlights are installed? HID's? If they are, they are Hi Frequency Emitters if not shielded correctly in their housings.

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Steven Mechanic
Spokane, Washington
Steven Default
 

Why do you have 10 companies tagged for your post?

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Scott Manager
Claremont, California
Scott Default
 

Hi Steven, we've since cleaned this up and I'll reach out to Caleb shortly. Thanks!

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Steve Diagnostician
Chester Springs, Pennsylvania
Steve Default
 

Thanks Scott

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Steve Diagnostician
Chester Springs, Pennsylvania
Steve Default
 

Caleb, What type of antenna connector do you have on the back of the radio ? Standard plug ? If so, I would get a test antenna and plug it in and see if it makes a difference If it improves you know it’s in the antenna cord circuit. Steve A

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Chris Diagnostician
Commack, New York
Chris Default
 

Hey Caleb, I'm with Steve. plug an antenna right into the back of the radio. Eliminate any interference issues related to the cable.

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Carlos Mobile Technician
Rhode Island , United States of America
Carlos Default
 

I seen this problem before on the Corolla and Camry replaced back glass problem fixed

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Steve Diagnostician
Chester Springs, Pennsylvania
Steve Default
 

Carlo’, We see it on the Lexus and Toyota side when using the rear defogger , usually on FM only Steve

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Ray Diagnostician
North York, Ontario
Ray Default
 

This is a good AC ripple, battery voltage, engine block ground voltage drop on cranking to start, starter and alternator amps on start up, from a 2011 Corolla

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Caleb Technician
Mishawaka, Indiana
Caleb Update
 

Hey everyone. This one is solved by the customer actually. This morning I had individually disconnected each headlight bulb as part of my diag but it was inconclusive. The customer came in to pick up the car just now and told me both headlamp assemblies had been replaced during the body work. 2 of the bulbs are HID's. When he told me this it hit me that the I had not had both HID's unplugged at…

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Benton Technician
Eudora, Kansas
Benton Default
   

I would pull the front bumper cover off and check the grounds that bolt to the front fender bracket on either side, below the headlamp. They're supposed to masked off when refinished so you have a bare steel connection. Edit: i'm glad it's figured out!

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Caleb Technician
Mishawaka, Indiana
Caleb Default
 

Thanks Benton. I had already ground both of those down to bare metal with no change. I should have been more specific when I said I cleaned the grounds in my original post.

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Dustin Technical Support Specialist
Escondido, California
Dustin Default
   

Awesome You got it figured out. I have seen aftermarket controllers that do not have filters for all the emitting frequencies thus causing issues like that. Sub par quality parts that "work" but cause other problems to chase instead. Ultimately they save $1 from not installing surface mount components that could have avoided this issue. I'm new to this site but I'm glad we have a wealth of…

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