C5 Electrical issues
Thread Starter
Navigator
Joined: Sep 2018
Posts: 9
Likes: 1
C5 Electrical issues
My '02 has several electrical issues that I'm not sure are related, or not.
1. I am intermittently getting the theft deterrent non-start, generating code B2721. After the three minute timer lapses, it will always start.
2. I am sometimes getting a pop noise in my aftermarket amp and it will sometimes briefly turn off when the brake lights trigger, blinker, AC fan turns on, and when other random items switch on. I tried running a dedicated ground and even swapping the amp with an identical one that I have. If I turn the flashers on, I can hear a light thump in the subs when the amp stays on. The interior lights also go slightly dimmer when I apply the brakes, then regain their intensity. The interior lights will pulsate in unison with the flashers.
3. Finally, over the past several years, I am on my third flasher/blinker module (not fun to replace), and my third AC fan resistor.
I tried cleaning the ground connection to the frame that is by the battery. I am getting just over 13 volts at the battery when its running with a bunch of stuff turned on. Any thoughts on what may be causing these wierd electrical issues?
1. I am intermittently getting the theft deterrent non-start, generating code B2721. After the three minute timer lapses, it will always start.
2. I am sometimes getting a pop noise in my aftermarket amp and it will sometimes briefly turn off when the brake lights trigger, blinker, AC fan turns on, and when other random items switch on. I tried running a dedicated ground and even swapping the amp with an identical one that I have. If I turn the flashers on, I can hear a light thump in the subs when the amp stays on. The interior lights also go slightly dimmer when I apply the brakes, then regain their intensity. The interior lights will pulsate in unison with the flashers.
3. Finally, over the past several years, I am on my third flasher/blinker module (not fun to replace), and my third AC fan resistor.
I tried cleaning the ground connection to the frame that is by the battery. I am getting just over 13 volts at the battery when its running with a bunch of stuff turned on. Any thoughts on what may be causing these wierd electrical issues?
Drifting
Joined: Mar 2015
Posts: 1,420
Likes: 302
From: CSRA, SC
1: B2721 means the reading on the resistor in the key is not right. Possibilities: key resistor contacts are fudged. key switch contacts for the resistor are fudged. Inspect and replace as necessary.
2. consult car audio forum here
3. keep replacing it they go bad. try to find an OEM part if you've been buying Guangzhou specials from chinazon.
Your problems are unrelated, but that should be good news.
I once had lunch with the CEO of an electronics vendor I worked with at the other equipment manufacturer that I worked at. He worked at the company that made the C5 keyswitch back in the day (forget now who that was) and he told me to make sure to always insert the key straight in. Much misalignment of the key can tangle up with the contacts that read that resistor and permanently bork them.
2. consult car audio forum here
3. keep replacing it they go bad. try to find an OEM part if you've been buying Guangzhou specials from chinazon.
Your problems are unrelated, but that should be good news.
I once had lunch with the CEO of an electronics vendor I worked with at the other equipment manufacturer that I worked at. He worked at the company that made the C5 keyswitch back in the day (forget now who that was) and he told me to make sure to always insert the key straight in. Much misalignment of the key can tangle up with the contacts that read that resistor and permanently bork them.
Thread Starter
Navigator
Joined: Sep 2018
Posts: 9
Likes: 1
Thanks for the reply. I have considered replacing the ignition switch and cylinder, but didn't want to just start throwing parts at it.
As far as the subs sometimes popping when various things switch on, I'm still trying to find what's causing that.
As far as the subs sometimes popping when various things switch on, I'm still trying to find what's causing that.
Drifting
Joined: Mar 2015
Posts: 1,420
Likes: 302
From: CSRA, SC
You can try replacing the key first since they're inexpensive. But only do it if the resistor looks worn/chewed up. If the key looks fine it's going to be the ignition switch because that's all there is at play. It could be dirty inside, it could be bent, broken, whatever. The audio problems sound like a poor ground path for something. Check and clean them all. It's good routine maintenance on C5s anyway.
Thread Starter
Navigator
Joined: Sep 2018
Posts: 9
Likes: 1
Checking the resistance of the keys' pellets, I'm getting 7430 and 7470 ohms, making them #13 keys, based on a chart i saw online. I'll try buying a replacement and see what happens. Maybe the little pellets are worn. Not sure what they should be as far as thickness. Next will be the ignition switch.
As far as the amp noise goes, i'm still trying to root-cause that.
As far as the amp noise goes, i'm still trying to root-cause that.
Thread Starter
Navigator
Joined: Sep 2018
Posts: 9
Likes: 1
I thought I would post an update on my issues. Replacing the key did nothing for the intermittent TDR problem. Replaced the ignition switch and it has never happened again.
As far as the audio popping noise, I introduced a device ahead of the amp that uses current in the speaker wires to provide the 12V remote signal. Popping gone.
I replaced the hazard switch with a supposed OEM one, and so far so good.
Finally, I blew yet another AC blower resistor module -- probably the 5th one in as many years. I am going to go an actual parts store now and get one with a warranty.
As far as the audio popping noise, I introduced a device ahead of the amp that uses current in the speaker wires to provide the 12V remote signal. Popping gone.
I replaced the hazard switch with a supposed OEM one, and so far so good.
Finally, I blew yet another AC blower resistor module -- probably the 5th one in as many years. I am going to go an actual parts store now and get one with a warranty.
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Pro
Joined: Jan 2016
Posts: 524
Likes: 126
From: Sandown NH
Installing a hyperflash harness bypasses the stock hazard switch and is a very easy to install under the dash. Its primary purpose is to get rid of hyperflash when LED
turn signal bulbs are installed but a secondary benefit is it bypasses the problematic hazard switch.
turn signal bulbs are installed but a secondary benefit is it bypasses the problematic hazard switch.