I have a 2001 C5. History leading up to current problem: I recently repaired the ignition switch after getting the typical DIC warnings (Service Active Handling, Low Voltage, Reduced Engine Power). Drove a few days with no warning and no problems. Then Service Active Handling and eventually Low Voltage came back so I removed the steering column and replaced the SWPS. Last night, after installing the steering column and hooking up the battery, within 5 minutes buzzing started from the fuse box under the dash on passenger side. This continued while I checked battery voltage at 11.35v. While buzzing, I touched the relays and discovered both Monitored Load Control and Courtesy Lamps relays were vibrating. After about 10 minutes, the buzzing stopped when the light under hood went off. I turned the ignition to ON and dash lights were very weak and no messages on the DIC. Today, I took the battery in for load testing - battery is good (and 12.59v after quick charge)
What do I do now? Replace both relays? Or, something else?

 

A little help here, please! Anyone?

 

You have a voltage issue somewhere. Bad connection at the battery, something wrong with the ignition switch OR the connector that plug into it.

Remove the relay or find the FUSE for the relay. At the fuse, measure the two test points on top of the fuse to chassis ground when the relay is buzzing. You should see FULL BATTERY VOLTAGE at the fuse test points.

Start there and see where you are at. You can also check some of the other IGNITION POWERED fuses and see what the voltage is.

Bill

 

Were you still getting the buzzing and dim lights after this "quick charge"? I understand it happening with your battery in the 11 volt range. 12 volt electronics don't like being fed 11 volts.

On a side note. I have had quite a few batteries tested over the years. I can say that the testers were right about 30% of the time if that. They just can't test a battery under normal loads and conditions. In fact the last time I had one checked I left it on charge over night. Unhooked it and brought it straight to the store. They put it on the machine. It read 12.62 volts. They did one test crank cycle on it. Their machine read that that one crank cycle brought the battery down to 11.8 volts and 54% of rated capacity. Guess what? Their green light came on and read out that the battery was GOOD but needed a charge. Anyone with any sense whatsoever would know that battery was toast.

You will also notice that when you bring a battery back to where you bought it to have it tested and you're not watching the numbers on the machine yourself, a borderline trash battery will more often than not test GOOD. They don't want to warranty it if its borderline. If you bring a battery into a store that DID NOT sell you the battery it will more often than not test BAD. They would be more than happy to sell you a new one.

Know what to look for and watch the tests yourself.

 

I agree. Read the battery voltage at the battery when the buzzing issue is happening . If the small load on the battery is causing the battery to go under voltage, its junk.

Bill

 

Thanks for the helpful tips, BC and reath1! I will go and check it out

 

Okay. I went through the troubleshooting tips. This is what I discovered:
The ignition switch connector looks okay to me (no visible corrosion). I checked battery voltage at 12.40v. Attached battery cables, voltage at 12.26 with hood light on, no buzzing. Turned key to ON, dash sequence and lights were normal. Turned key OFF, checked battery cables at 12.20v with hood light on, 12.26v with hood light off.

About 90 minutes later, I checked voltage at Monitored Load fuse at 11.88v (with hood and cabin lights on), 12.20v after lights go out. Checked other fuses at about 12.20v.

About an hour later, voltage at battery cables were 12.30 (hood light off). Turned key to ON and checked ignition fuses (with hood and cabin lights on) voltage at 11.85, and dropped quickly as I checked each fuse until the last one at 11.55v. I quickly tried turning over engine but got the dreaded clicking sound, voltage on the dash showed 9v and got Low Voltage on the DIC. I turned the key to OFF and checked the battery cables at 12.00v.

About 30 minutes later, I checked the battery cables at 6.67v (hood light off).

So, what do you think?

 

Your battery has little or no reserve capacity. Its junk. I recommend getting a new battery.

NO WAY should it fall off as quickly as it did if it was good

BC

 

Yup. I concur. Battery is toast. Another case of battery testing good and being junk.

 

Thanks, Guys! I will take the battery back and watch the load test, this time insist that they refund my money.

 

Just for grins, I checked the battery this morning and voltage is back up to 12.10, and that's without putting it on the charger. Is that normal for a bad battery?

 

Batteries that drop to 6 vdc don't usually pop back up to 12 vdc. Something is very strange. Have the battery fully tested and make sure that they check CCA and reserve capacity.

Recommend having it tested somewhere that doesn't have to honor the warranty and then at the place that cares about the warranty.

BC

 

Thanks, Bill. What is CCA?

 

CCA = Cold Cranking Amps