2007 Impala LT, fog lights stuck on - Chevy Impala Forums
Chevy Impala 8th Gen Discussion W-Body 2006-2013 (2014+ Limited). Discuss all Chevy Impala 8th Generation Performance and Technical Discussion here.

User Tag List

 8Likes
Reply
 
LinkBack Thread Tools Display Modes
post #1 of (permalink) Old 3 Weeks Ago Thread Starter
Junior Member
 
Ahnt's Avatar
 
Join Date: Aug 2019
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
2007 Impala LT, fog lights stuck on

I came out to my car a few weeks ago and noticed the fog lights where on. I started the car, hit the button to turn them off and they where still on. Even turning the high beams on, fogs still on.



I ended up pulling the fuse. A few days later I put the fuse back in, and the lights operate normal. No issues at all. A few days after that, same issue.



I've done the pull the fuse, put the fuse back in a few times now and sometimes its good for a few days, other times only a few hours.



The fuse is good obviously, the lights are good, everything else works so I'm kinda stumped. I asked about a fog light relay (possibly stuck?) at O'reillys and they showed me a picture of it, but I cannot find anything close to that in / on or around the fuse panels in the car, or under the hood.



Anyone ever have this issue?
Ahnt is offline  
Sponsored Links
Advertisement
 
post #2 of (permalink) Old 3 Weeks Ago
Member
 
a55bruce's Avatar
 
Join Date: Dec 2012
Location: Western PA
Posts: 85
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Thanks: 1
Thanked 20 Times in 18 Posts
Quote:
Originally Posted by Ahnt View Post
...The fuse is good obviously, the lights are good, everything else works so I'm kinda stumped. I asked about a fog light relay (possibly stuck?) at O'reillys and they showed me a picture of it, but I cannot find anything close to that in / on or around the fuse panels in the car, or under the hood.
The relay is probably a PCB soldered-in relay inside/under the underhood fuse block.
The BCM grounds the relay coil to energize the relay. Either the BCM is turning the relay on or there is a bad wire somewhere shorting to ground energizing the relay.
Check for the dash panel indicator, if it's lit then the BCM is turning the fog lights on. Maybe the switch or wiring from the switch to the BCM. Disconnect the fog light switch. Try a BCM reboot by disconnecting the battery.
Other things to check, the fog light switch, corrosion in the fuse block especially around the fog relay. Next time they're ON, give the fuse block a bump, and try moving the fuse block wiring harness.

OR, leave the fuse out.
plano-doug likes this.
a55bruce is online now  
post #3 of (permalink) Old 3 Weeks Ago
Senior Member
 
plano-doug's Avatar
 
Join Date: Aug 2009
Location: Plano, Texas
Posts: 2,480
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Thanks: 130
Thanked 361 Times in 337 Posts
Quote:
Originally Posted by a55bruce View Post
The relay is probably a PCB soldered-in relay inside/under the underhood fuse block.
The BCM grounds the relay coil to energize the relay. Either the BCM is turning the relay on or there is a bad wire somewhere shorting to ground energizing the relay.
Or, the relay has failed in a closed position. (Unusual, but not impossible )
...

I have attached a drawing for the fog lights.

The BCM drives the relay which in turn powers the fog lights. According to the drawing, the relay is indeed in the underhood fuse block. But the drawing is not clear if it's on the topside, or whether it can be easily removed. That is, it's not clear if it's plugged in versus being soldered in place on the lower layer inside the fuse box.

I would try to measure the voltage across the relay coil. That may require tracing the wire back from the fusebox (C2-H5, D-GN/WH) to a good place to probe it. With the car off, measure the voltage between B+ (+12V) and C2-H5. If it measures close to +12V, then the BCM pin is stuck low, or the wire going to the BCM is shorted to GND somewhere along the path. If there's no voltage across the relay coil, then the relay is somehow stuck closed. Or there's a short outside the relay between its input (B+) and pin C2-G1.

If the relay can be removed easily, and the fog lights go out (with key off), then the relay is bad. If it's soldered in place, then, without removing the relay, remove the fuse to verify the fog lights go out. This will indicate if the short between B+ and C3-G1 is upstream or downstream of the fuse.

The idea is to keep checking the easy stuff, but eventually, it may become necessary to de-solder the relay. With the relay removed, if the lights stay on, the short is in the relay box. If the lights go out, before soldering in a new relay, I would get some jumper wires and temporarily wire up the new relay to verify everything works correctly _before_ soldering it in place
...
On another forum recently, a guy paid to have the tank dropped and a new fuel level sensor installed. But that didn't fix the gas gauge. My thought was, why the heck didn't they check the level sensor functionality _before_ they put the tank back in? SMH.

HTH.

_

If your socket set is all the same brand, you might be a city slicker.

.
plano-doug is offline  
Sponsored Links
Advertisement
 
post #4 of (permalink) Old 3 Weeks Ago Thread Starter
Junior Member
 
Ahnt's Avatar
 
Join Date: Aug 2019
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Thanks plano-doug and a55bruce.

I'll have to pop the under hood fuse box loose and look behind. I'll attach a link to the relay, at least what Autozone and O'reilly's shows.

https://www.autozone.com/electrical-...826/867084_0_0

It's a blade type fuse, so I'm assuming it's not soldered?


So far I've tried unhooking the battery for about an hour and reconnecting. Tapping the fuse box (underhood) a little bit, swapped the headlight switch assembly with a known good one and checking as much of the fog light wiring to the fuse box as I could.
Ahnt is offline  
post #5 of (permalink) Old 3 Weeks Ago
Member
 
a55bruce's Avatar
 
Join Date: Dec 2012
Location: Western PA
Posts: 85
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 11 Post(s)
Thanks: 1
Thanked 20 Times in 18 Posts
Quote:
Originally Posted by Ahnt View Post
I ended up pulling the fuse. A few days later I put the fuse back in, and the lights operate normal. No issues at all. A few days after that, same issue.

I've done the pull the fuse, put the fuse back in a few times now and sometimes its good for a few days, other times only a few hours.
Makes it sound like an intermittent wiring problem (possibly shorting to ground caused by vibration on the wiring)
Quote:
Originally Posted by plano-doug View Post
Or, the relay has failed in a closed position. (Unusual, but not impossible)...
Relays will stick closed but usually they fail to open after being used.
What's unusual is that this relay appears to close on it own.
Another possibility is that there's some wet/damp corrosion at the relay that is shorting C2-H5 to ground.
I'd check the fuse block next.
plano-doug likes this.
a55bruce is online now  
post #6 of (permalink) Old 3 Weeks Ago Thread Starter
Junior Member
 
Ahnt's Avatar
 
Join Date: Aug 2019
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Nothing under the fuse box. No fuses at least.
Ahnt is offline  
post #7 of (permalink) Old 2 Weeks Ago Thread Starter
Junior Member
 
Ahnt's Avatar
 
Join Date: Aug 2019
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Or relays I mean. Nothing at all under the fuse box.....
Ahnt is offline  
post #8 of (permalink) Old 2 Weeks Ago
Member
 
mdubyk's Avatar
 
Join Date: Feb 2018
Location: Atlanta, GA
Posts: 83
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Thanks: 2
Thanked 9 Times in 9 Posts
Garage
Fog lamp operation:


"Battery voltage is applied at all times to the coil and switch sides of the FOG LAMP PCB Relay located in the underhood fuse block. When the fog lamp switch is turned ON, ground is applied through the fog lamp switch signal circuit to the body control module (BCM) indicating the fog lamp request. In response to this signal, the BCM applies ground to the fog lamp relay control circuit energizing the FOG LP PCB Relay. With the relay energized, battery voltage is applied through the switch side of the relay, the FOG LAMPS fuse, and the fog lamp supply voltage circuits illuminating the fog lamps. At the same time the BCM sends a message via serial data to the instrument panel cluster (IPC) requesting that the fog lamp indicator be illuminated."



When the ignition switch is off, the fog lamp switch does not turn on the fog lamps. The BCM must be awake to give the ground for the fog lamp relay. If the BCM is not awake and the fog lamps are lit, you have an intermittent ground at Underhood Relay Block connector C2 pin H5.
plano-doug likes this.

Last edited by mdubyk; 2 Weeks Ago at 06:01 PM.
mdubyk is offline  
post #9 of (permalink) Old 2 Weeks Ago
Senior Member
 
plano-doug's Avatar
 
Join Date: Aug 2009
Location: Plano, Texas
Posts: 2,480
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Thanks: 130
Thanked 361 Times in 337 Posts
ConFused, Relay confused

Quote:
Originally Posted by Ahnt View Post
Or relays I mean. Nothing at all under the fuse box.....
I'm stumped. Totally. In the underhood fuse block (of my 2007 Impala SS), I removed the inserted panel that snaps into the housing that's bolted to the fender.

There are several cables that come into the box and connect to the backside of the panel which holds the fuses and relays seen on the topside. There was no sign of any relays down inside.

On the top side, the fog lamp fuse is there, as are the headlamp fuses. But no sign of the fog lamp relay, nor the headlamp relays. Yet the schematics I have (attached) indicate that those relays are mounted on a PCB in the underhood fuse box.

I can take another look tomorrow, but I doubt I'll find anything. Any relays buried inside the fuse box (ie, not on the top layer) would have to be inside the connector backshells of the cables coming into the box. And that would be whack.

If you look at the attached drawings - sorry about failing to attach the fog light schematic earlier - you can see the fuses and relays for the fog lights and head lamps. But when you look at the attached legend inside the fuse box cover, only the fuses are listed - no sign of the relays.

The 2000-2005 Impalas had 2 underhood fuse boxes, but the gen8 cars only have the one AFAIK. For sure, I didn't see another one during tonight's inspection.

It seems like I've seen a lower layer in a fuse box somewhere, but all I saw on the lower layer tonight appeared to be connectors. No signs of PCB mounted relays.

So I have to punt for now. Tomorrow, I'll look some more. Somewhere, there are 5 relays missing (3 headlamps, 1 fog, 1 parking).

Doug

.
Attached Thumbnails
Click image for larger version

Name:	2007_impala_headlamps_schematic.png
Views:	6
Size:	40.1 KB
ID:	146093   Click image for larger version

Name:	2007_impala_fog_lights_schematic.png
Views:	7
Size:	38.7 KB
ID:	146095   Click image for larger version

Name:	SS_fuse_box_legend.jpeg
Views:	7
Size:	899.7 KB
ID:	146097  
Ahnt likes this.

_

If your socket set is all the same brand, you might be a city slicker.

.

Last edited by plano-doug; 2 Weeks Ago at 07:58 PM.
plano-doug is offline  
post #10 of (permalink) Old 2 Weeks Ago Thread Starter
Junior Member
 
Ahnt's Avatar
 
Join Date: Aug 2019
Posts: 6
Mentioned: 0 Post(s)
Tagged: 0 Thread(s)
Quoted: 3 Post(s)
Thanks: 0
Thanked 0 Times in 0 Posts
Yeah that is very strange. I can say this, it's 100% in the box area. Tonight I had them stick on again, and I smacked the fuse box (under hood next to battery) three times and the fog lights turned off.



I didn't see any relays when I had the top panel off, but it's in the box somewhere.



Would it be possible that the fog light relay is tied in with another relay?
Ahnt is offline  
post #11 of (permalink) Old 2 Weeks Ago
Member
 
mdubyk's Avatar
 
Join Date: Feb 2018
Location: Atlanta, GA
Posts: 83
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Thanks: 2
Thanked 9 Times in 9 Posts
Garage
I found this earlier this morning:

@Bill58:
"There are 10 PCB relays that are found only by taking apart the fuse block, soldered and "non-serviceable" relays."
sheila likes this.
mdubyk is offline  
post #12 of (permalink) Old 2 Weeks Ago
Senior Member
 
hatzie's Avatar
 
Join Date: Nov 2009
Location: Baker River Valley, NH
Posts: 938
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 154 Post(s)
Thanks: 82
Thanked 149 Times in 131 Posts
Depends on what you mean by non-serviceable...
This means that GM would like you to get rid of the car rather than repair it.
Desoldering a relay from a PC board and replacing it ain't that big of a deal.
I'd take the box apart, find the relay part number, order one, and replace the little bugger.

2009 Impala SS
"Speed never killed anyone. Suddenly becoming stationary... that's what gets you." Jeremy Clarkson
hatzie is offline  
post #13 of (permalink) Old 2 Weeks Ago
Member
 
mdubyk's Avatar
 
Join Date: Feb 2018
Location: Atlanta, GA
Posts: 83
Mentioned: 1 Post(s)
Tagged: 0 Thread(s)
Quoted: 20 Post(s)
Thanks: 2
Thanked 9 Times in 9 Posts
Garage
For me, the term "non-serviceable" isn't in my vocabulary.

If it can be taken apart, it can be repaired.
hatzie likes this.
mdubyk is offline  
post #14 of (permalink) Old 2 Weeks Ago
Senior Member
 
hatzie's Avatar
 
Join Date: Nov 2009
Location: Baker River Valley, NH
Posts: 938
Mentioned: 7 Post(s)
Tagged: 0 Thread(s)
Quoted: 154 Post(s)
Thanks: 82
Thanked 149 Times in 131 Posts
Got any pictures of the little monster popped open and the PCB showing?

I've had a Hakko 472D for years but there are Chinese knockoffs of that de-soldering gun that are only $100 now.
I'd take a whack at it even if I only had solder braid, flux, and a good iron.

2009 Impala SS
"Speed never killed anyone. Suddenly becoming stationary... that's what gets you." Jeremy Clarkson
hatzie is offline  
post #15 of (permalink) Old 2 Weeks Ago
Senior Member
 
plano-doug's Avatar
 
Join Date: Aug 2009
Location: Plano, Texas
Posts: 2,480
Mentioned: 6 Post(s)
Tagged: 0 Thread(s)
Quoted: 365 Post(s)
Thanks: 130
Thanked 361 Times in 337 Posts
Fuse panel removed

Here's a pic of what I was calling the fuse panel. It has been removed from the lower housing, and this is a view from the back. You can see four large connector backshells, all over 3" long and 1.2" deep, with somewhat varying widths. These are large enough to house relays, but I'm doubtful anyone would design that way.

I tried to remove one of them to inspect inside, but couldn't figure out how to get it to release. Out of fear of breaking one of the plastic barbs, I gave up.

No doubt, the backshells are large, but once the wires are run into them and turned 90 to mate with the fuse panel, I doubt there's much room left to house any relays.

Based on my observation and what others have posted here, I'm pretty sure the missing relays are elsewhere, as I'm about to show in my next post

Doug

.
Attached Thumbnails
Click image for larger version

Name:	back_shells.jpeg
Views:	7
Size:	495.0 KB
ID:	146099  
Ahnt likes this.

_

If your socket set is all the same brand, you might be a city slicker.

.
plano-doug is offline  
Sponsored Links
Advertisement
 
Reply


Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Chevy Impala Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are On
Pingbacks are On
Refbacks are On

 
For the best viewing experience please update your browser to Google Chrome