Couple days ago, went to start the car. All instrument panel needles made their full cycle, and I heard what I believe is the fuel pump priming noise. (key is in on position at this point). Went to crank over and the starter tried to kick over, but wouldn't and got prgressively weaker with additional attempts (2-3).

Rolled out the shop battery charger/starter, hooked up and it cranked right over and ran fine. Fast forward 9-10 hours, try to unlock the car with the fob, and it won't work at all. Had to use the key to unlock the door. No panic button response, or hatch response when either button pressed. No fuel pump priming on key insertion, either. Got it jump started and ran for the 10 miles I needed to travel.

Pulled codes when I got home:

B0851 (SCM) Battery 1 out of range
B0432 (BCM) Rear defogger relay ckt
B0503 (BCM) RH DRL relay ckt
B0508 (BCM) LH DRL relay ckt
B2593 (BCM) Column Lock/Unlock Drive (B)
?2809 Unable to find any definitive info for this code.

Then disconnected all accessories with the exception of the climate control unit, to include:

-After market stereo and associated custom wiring harness
-Traction control switch
-Passenger Airbag enable
-Fuel door release switch
- Both the ashtray 12v receptacle and the 12v accessory receptacle inside the center console.

Put the charger on the car, let it sit for 1/2 hour or so, disconnected charger, and it started right up. Left it in the torn down state overnight and most of the next day (yesterday) and each time it would start instantly (like I'm used to).

Checked battery voltage with car off, and am getting roughly 11.78 vdc
Was suggested to me that to check the alternator, get the car running, then disconnect the positive lead from the battery. If the car dies than the alternator is failing, if it continues to run, then the alternator is fine. Performed the following test and the car ran without issue while the positive lead was disconnected. Probably let it run for close to five minutes.

Checked both under hood, and kick panel fuses for continuity. Did not check any of the realys though.

When the car does start, all interior lights operate, the HUD operates, DRLs work, fog lamps work, turn signals and 4 ways work, as well as raising and lowering of the headlights in either high or low beam mode.

Thinking I may have made an error during the aftermarket stereo head unit installation, which is the root cause of my whole problem, I removed the custom wiring harnesses, and the new head unit itself. Reconnected stock Bose head unit, turned it over to make sure it was connected properly and operating, and let it sit overnight last night.

Tried to start it this morning and was met by starter not being able to turn over (same symptom). So it seems that the custom wiring harness and new head unit can be ruled out as the cause of the problem. Removed factory head unit at this point.

More codes from this morning after my little experiment:

B2282 (LDCM) Battery 1 Fault
B2283 (RDCM) Battery 1 Fault
U1160 (IPC) Loss of Communications with LDCM
U???? (HVAC) I'm almost certain that the code was the same as the IPC code (U1160).

Last thing I tried was placing an ohm meter between the negative battery cable (still connected to the battery) and what appears to be a ground point that's just tied to the negative battery cable. The ground point has a ring lug on it and is located an inch or two in front of the battery, at/under the bottom of the battery tray. The reading I got was 17.xx ohms. Shouldn't this reading be more like .001-.005 ohms? The cable is barely a foot long.

Anybody that can provide an idea of where to go from here, your help will be deeply appreciated.

Thanks,
Bob

 

Until you install a new, fully-charged battery or a known good one that holds 12.6--12.7 volts overnight (unconnected) you are just chasing your tail. C5s hate marginal batteries. 11.78 volts is effectively dead.

New battery, clear codes, see what happens/what codes come back.

 

Will do. Thanks for replying!!

 

You need a quick lesson in electronics.

1, NEVER EVER connect an OHM meter in a circuit with voltage! The circuit under test needs to be completely electrically isolated to measure resistance.. It will give false readings and damage the meter if voltage is present in the measured circuit.

2. NEVER disconnect the battery from the alternator when the engine is running. The alternator is internally regulated and can go to MAX output if the output is not properly connected to the battery. It also does not output pure DC Voltage and you can sometimes hear the DC Ripple on the stereo and sometimes see the lights flicker. The sensitive electronics don’t do well if they don’t get the correct voltage and voltage levels. The battery acts as a STORRAGE device and filters out all that stuff.

Your battery is marginal to say the least. You may also have an excessive parasitic current drain on the battery when the car is OFF and in the sleep/security mode. The max current you should read between the NEG battery terminal and the Neg battery cable in sleep mode is 20-25 milliamps. If your battery doesn’t have the correct reserve capacity, it will go flat relatively quickly even at that small of a current draw. It takes 10-12 min for the BCm to go into sleep mode after shutdown.

Have the battery FULLY charged and then fully tested. Make sure that the electrolyte levels are correct before you charge it.

Make sure that they check Cold Cranking Capacity and Reserve Capacity.

Let us know how you make out.

Make Sure that you clear ALL your DTCs after you connect the battery. The 97-2003 battery terminal bolts need to be clean and tight and properly torqued to 11 FT/LBS for proper connection.

Bill

 

As for point #1, I should have known better, as I have an electronic related occupation. BTW, with no battery terminals connected, that cable i wrote of earlier reads .002 ohms.

Your second point is invaluable information. I didn't know any better, and seems as though i got extremely lucky not to damage anything during the "test". Ignorance isn't an excuse, but now I've got a better understanding about that type of situation. Many thanks to you, sir.

I took the old battery in for core and bought a new one. Didn't ask them to do any sort of diagnostics on it. Just wanted to get the new one and get it installed. Would have been a good idea for them to test it, as that would've more or less told me that the batttery was the problem all along. Hindsight.....

I'm don't know how to use the multimeter to read current, I always thought a clamp on device that plugged into the meter was necessary.
Love if you could further explain, or point me to a link where I may be able to figure it out for myself.

New battery is in and connected, no codes came up that needed to be cleared, however I put the Bose head unit back in and reconnected it to see if the problem reoccurs tomorrow morning. I don't own a torque wrench to ensure proper battery terminal bolt tightness, so they're wrench tightened.

I can say, without a doubt, the engine cranked effortlessly. This is the first time I can remember since I owned the car that the crank/start cycle was so clean. Hopefully a good sign.

I'll update tomorrow if the problem persists.

Thanks again for taking the time to respond to my problem Bill, and impart a little knowledge while doing so. It's very much appreciated.

Bob Schlickman

 

Bob

Each meter is unique and my exact METER set up will look a little different than yours. The theory is the same:

Current measurements are done in series with the load. You disconnect the NEG battery terminal and place the meter in series with the Neg battery lead and neg terminal terminal.

The meter will need to read at least 8-10 amps. When you first connect the meter to the load, the car will come to life and you will see a 5 - 8 amp current draw. As minutes go by, the load will drop in steps and then settle out in the 20 Milliamp range Some meters will read .02 Amps which is the same as 20 milliamps

Heres my meter connected:







The meter has a SEPARATE CURRENT JACK.

Each time that the BCM wakes up,, it will take 10-12 min to go back to sleep.

BC

 

Haven't gotten to the current measurement yet, but I notice you're using the same type of battery that I purchased yesterday. It feels sloppy in the tray, side to side and front to back movement. If yu don't mind me asking, what did you do to secure it in place?

I've already removed the spacer washer on the bottom of the triangle piece, to allow the lip to slip/fit into piece B, and retightened. Helps somewhat, but the rest of the battery shifts around in its tray more than I;d care for it to. Should i be using the "A" and "B' pieces of plastic that come with the battery? Also the handle on the negative side slips completely out of its channel, almost dropped the battrey because of this. Does this seem like normal behavior? Suggestions most welcome.

Edit: Did your battery come with protector caps/sleeves for the top facing terminals, or did you need to buy them seperately? Mine came with none. Wondering if that's the norm.

Thanks Bill,
Bob Schlickman

 

Bob

That battery was purchased in 2004 I use a triangle hold down bracket. Cant remember if its stock or aftermarket. If I shove the base of the battery into the rear hold down slot and slide that triangle part tight into the battery and tighten it down, It's very secure in the tray. NO MOVEMENT at all

Bill

 

I was able to secure the barrery properly. Turns out that the A nd B plastic pieces do absolutely nothing in terms of battrey position and stability,

Now the DIC reports baterry voltage of between 13.1 and 14.1 or 2 volts, with all acessories on full bore. (lights up and switching between low and high/turn/4 way signals/back and brake lights, both windows operating, both together and ar different intervals, climate control on using max fan speed, along with the Bose unit turned all the way up. With all this going on simultaneously, the DIC voltage reading never dips under 13.6. Now all I have to do is reassemble the IPC/center console, make sure all reconnected gear works, and it's time for a spirited spin.

Once again Bill, you never cease to amaze.

Thanks again,
Bob Schlickman

 

One more question for Bill, or anyone else that may be able to help. Now that the above is sorted out, I've had the opportunity to drive it for a day or so, but something seems off horse power wise. My question is, since the battery went dead, was recharged, disconnected and reconnected multiple times, is it possible that my custom tune no longer exists and the tuning has reverted to basic stock settings?

Thanks,
Bob Schlickman

 

NO! The tune is resident in NON VOLATILE MEMORY and must be re-flashed with a tuning device to alter/change or remove the resident tune.

What can change when the battery is removed are the Long Term Fuel Trims. They are volatile and will relearn in a short set of drive cycles. They effect your PART THROTTLE CRUISE only BUT,,, if there off significantly ; they can have some effect on WOT AFR until they are relearned. The Idle can also be effected but will relaern on its own also

What MODs do you have and has your car ever been tuned and if so, what type of tune do you have. (ie. Professional In shop Dyno tune, Professional Road Tune, Mail Order Tune,, CANED Tune (like a Hypertech Tuner) etc.............

Bill

 

Modest set of mods. Billy Boat shorty headers piped through Random Tech high flow cats, into a pair of Borlas Stinger cans, a Pro-Yank 3200 stall installed in an upgraded xmission, and a P-1SC Procharger unit delivering roughly 8-11psi boost. When the mods were installed, had it dyno tuned in the same shop that did the install for me. Nice shop up here in NH called Pro Tree Performance. From my experience with them, they do good work and seem to care about customer satisfaction.

Before the mods took it to another dyno tuning place.
Bone stock was 294.97 hp and 314.75 ft lbs @5300.

Then I bought one of those West Coast Corvette stage 3 packages. Don't have a lot good to say about it. The only pieces still in use are the shorty headers and the MSD plug wires. After install of the package components and retune at the same place that provided my baseline numbers, it ran 317.28hp and 331.91 ft lbs @ 5300. Felt like the money spent on the kit, install and retune was wasted, so started looking for different options.

Found Pro Tree, had them undo most of the stage 3 kit, then add the procharger, stall converter, heavy duty xmission, and all the plumbing from the headers back. A final dyno retune at their shop resulted in 472.24 hp and 424.24 ft lbs @ about 6300 rpm.

That's my history to this point. Not sure what's next....

Bob

 

With your extensive set of mods,,, The only way to REALLY get a true picture of whats going on would be to DATA LOG THE ENGINE and see what LTFT, KR and timing are and what the AFR's are in cruise and WOT.

Give it some runtime and drive cycles to see if it stabilizes and returns to what you expect.

BC

 

Will do.

Thanks, Bill.