electrical issue/ no start, complicated, look inside
Tech Contributor
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From: Oak Hill Virginia
Thread Starter
Racer
Joined: Jan 2011
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From: Houston TX
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
Likes: 3
From: Houston TX
Here is a quote from one of Bill Curlee's posts about isolating current drain problems:
There are several COMMON things that cause excessive current draw
-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off
Also check to see that you have not turned the interior light btoghtness control full clockwise as this turns on the interior lights and that the lids on the visor vanity mirrors are turning off the vanity mirror light.
There are several COMMON things that cause excessive current draw
-Seat multifunction switch & Lumbar Switch
- Bose Amp relay stuck on
- Alternator didoes bad and drawing current
- Headlight control module bad
- Interior light on (check in the dark)
- Added aftermarket accessory not shutting off
Also check to see that you have not turned the interior light btoghtness control full clockwise as this turns on the interior lights and that the lids on the visor vanity mirrors are turning off the vanity mirror light.
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
Likes: 3
From: Houston TX
I am delivering the pictures as requested,
The 1st pic is more accurate way of how I take the measurement, the numbers are still alarmingly high.
Ok so the good news is after 3 days the battery has not died yet after being fully charged but I did some tests and made an interesting discovery today.
With the multimeter set to DC I took the voltage at the purple wire on the starter and it was a consistent 12.4, with one try touching the black prob to the head and the 2nd try touching the black prob to the ngative battery post, while red probe was on the purple wire post on the starter. This should help with seeing what the problem is.
I wasn't able to perform the test for the #14 fuse yet as I do not have a wire long enough but I will try to do that tomorrow evening.
Thanks everyone these last 2 tests should get us close.
I will be more than happy to provide any additional pictures/videos upon request.
The 1st pic is more accurate way of how I take the measurement, the numbers are still alarmingly high.
Ok so the good news is after 3 days the battery has not died yet after being fully charged but I did some tests and made an interesting discovery today.
With the multimeter set to DC I took the voltage at the purple wire on the starter and it was a consistent 12.4, with one try touching the black prob to the head and the 2nd try touching the black prob to the ngative battery post, while red probe was on the purple wire post on the starter. This should help with seeing what the problem is.
I wasn't able to perform the test for the #14 fuse yet as I do not have a wire long enough but I will try to do that tomorrow evening.
Thanks everyone these last 2 tests should get us close.
I will be more than happy to provide any additional pictures/videos upon request.
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
With the multimeter set to DC I took the voltage at the purple wire on the starter and it was a consistent 12.4, with one try touching the black prob to the head and the 2nd try touching the black prob to the ngative battery post, while red probe was on the purple wire post on the starter.
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
Ok, how did you attach the leads to the cable and battery post. You did not actually stand there for 30 minutes did you? It has to be left on continuously.
When you took this voltage reading, did you have the meter leads plugged into the meter as in the pic i.e. red far left, and black middle?
When you took this voltage reading, did you have the meter leads plugged into the meter as in the pic i.e. red far left, and black middle?
No lucky i moved the red probe to the far right post for taking the starter voltage and moved the multimeter *** to 200 DC for the test
But isn't 12.4 good voltage for the purple post and if so why wouldn't the car be starting if the starter is getting good power?
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
Lucky I did not stand there for 30 minutes, was I supposed to take continous readings for 30 minutes? I simply disconnected the negative cable, disconnected under hood light, and waited 15 min for car to fall asleep before taking measurements, I observed the current for roughly 1 minute. I then came back 2 hours later with negative battery cable and underhood light still connected observed the current for 1minute with the same range of readings.
Ok, just wanted to make sure you had the meter setup properly. This is very concerning. The only time you should have 12 volts to the purple wire, is with the key on, clutch pedal depressed. Below is a picture of where the TDR (theft deterrent relay) is located. Access that relay and unplug the connector. Check to see if you have 12 volts on the purple wire with the relay unplugged.
Last edited by lucky131969; Jan 16, 2012 at 08:10 PM.
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Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
Ok lucky i think I'm doing it right by ill go back and reread and take some more pics for u.
Ok let me clarify the test was performed with the clutch pressed in and the key turned to the start position, when the key was not turned to start the reading was zero volts.
I will check the theft detterant relay and fuse #14 tomorrow
Ok let me clarify the test was performed with the clutch pressed in and the key turned to the start position, when the key was not turned to start the reading was zero volts.
I will check the theft detterant relay and fuse #14 tomorrow
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
That being said, the voltage to the purple wire is good, with the key to start, and clutch depressed. This suggests, that the following are good:
1) Ignition switch
2) Clutch switch
3) TDR
4) Wiring from the TDR to starter
No need to access the TDR for any voltage checks.
Finally, it also suggest that you have a problem with the solenoid.
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
Sorry about the confusion,
So could a bad starter solenoid possibly explain why the voltage reading on my dash reads only 11.9-11.6 on a fully charged battery?
I won't be able to get the starter out until this Friday at least, in meantime I can continue to do various tests.
So could a bad starter solenoid possibly explain why the voltage reading on my dash reads only 11.9-11.6 on a fully charged battery?
I won't be able to get the starter out until this Friday at least, in meantime I can continue to do various tests.
Racer
Joined: Oct 2011
Posts: 398
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From: woodstock ga
wow, all of this and the whole time i am thinking starter solenoid. not wanting to go from the top again, when you attempt to start do you get a rapid tapping noise coming from the area around the starter? if so this is a sign of a starter solenoid problem, either low voltage (batt drain, poor ground) or bad starter solenoid.
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
Likes: 3
From: Houston TX
wow, all of this and the whole time i am thinking starter solenoid. not wanting to go from the top again, when you attempt to start do you get a rapid tapping noise coming from the area around the starter? if so this is a sign of a starter solenoid problem, either low voltage (batt drain, poor ground) or bad starter solenoid.
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
Using the dash guages to determine the voltage of the battery is an excercise in futility. The guages show the state of health of the charging system NOT the state of health of the battery. With engine running the dash guages reflect the output voltage of the alternator.
With key on and engine off there are MANY electrical circuits in the C5 loading the battery so what you are reading on the guages is pretty much worthless.
To know the voltage of the battery you need to use a DMM directly across the batery posts with the neg battery cable disconnected. A good battery at full charge with no load will measure between 12.7 and 12.9 volts or more.
With key on and engine off there are MANY electrical circuits in the C5 loading the battery so what you are reading on the guages is pretty much worthless.
To know the voltage of the battery you need to use a DMM directly across the batery posts with the neg battery cable disconnected. A good battery at full charge with no load will measure between 12.7 and 12.9 volts or more.
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
I will give that a try tonight, I will also again try to jump start the car, if not the car is going up on jack stands tomorrow and I will take out the starter, I need to get to the bottom of this asap.
Tech Contributor
Joined: Jan 2007
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From: Dyer, IN
Good luck sir
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
Problem diagnosis by part swapping can get expensive quickly and can introduce new variables as you remove things to get to the one you will swap..
Some final thoughts. The meter setup in your pics is unacceptable for auditing the current(jjust resting the meter leads on the terminals is not sufficient), you still have not provided any pics of a setup like Bill showed in his thread. I urge you to determine where the current drain is, before you start taking the car apart i.e starter.
Good luck sir
Good luck sir
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
So today I went back to the corvette and I was greeted by a low voltage message on my dash. I then proceeded to take the amp measurements. here are the pictures as promised.
So the amps started out at 5.79, then went down to 3. and shot back up again to 4.9. I took measurements for about 40 minutes.
I did not take measurements for fuses as the battery was already in a dying state and I did not think attempting to start the car would be wise.
If I am doing something wrong please point it out from the pics, if not guide me to what I need to be checking for. There is a good chance that I will put the car on jack stands tomorrow and look under the car to see if I can find anything off unless told otherwise. Thanks
So the amps started out at 5.79, then went down to 3. and shot back up again to 4.9. I took measurements for about 40 minutes.
I did not take measurements for fuses as the battery was already in a dying state and I did not think attempting to start the car would be wise.
If I am doing something wrong please point it out from the pics, if not guide me to what I need to be checking for. There is a good chance that I will put the car on jack stands tomorrow and look under the car to see if I can find anything off unless told otherwise. Thanks
Tech Contributor
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From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
WOW!!!!!!!!!!!!! 
5 damn amps! That will EAT a battery in no time FLAT!
Something is NOT turning OFF when it should.
Open BOTH doors and the hood. Leave them open.. Take the SAME current measurements. When it settles out at the lowest current reading, with out disturbing the doors unplug the DRIVERS SEAT Connector and see if the current reading drops down.
Make SURE that you do NOT have any interior light left on. Examine your car in the DARK and look for light ON.
Pull the fuse for the rear DEFROSTER, and the BOSE AMP, one at a time and see if the current reading drops.
Remove the main power (BATT ) wire off the back of the alternator and see if the current drops.
Then disconnect the connectors on the head light control module. check for current drop.
Those are all the COMMON causes of excessive current draw.
BC
5 damn amps! That will EAT a battery in no time FLAT!Something is NOT turning OFF when it should.
Open BOTH doors and the hood. Leave them open.. Take the SAME current measurements. When it settles out at the lowest current reading, with out disturbing the doors unplug the DRIVERS SEAT Connector and see if the current reading drops down.
Make SURE that you do NOT have any interior light left on. Examine your car in the DARK and look for light ON.
Pull the fuse for the rear DEFROSTER, and the BOSE AMP, one at a time and see if the current reading drops.
Remove the main power (BATT ) wire off the back of the alternator and see if the current drops.
Then disconnect the connectors on the head light control module. check for current drop.
Those are all the COMMON causes of excessive current draw.
BC
Thread Starter
Racer
Joined: Jan 2011
Posts: 353
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From: Houston TX
Thanks Bill I will try the methods you stated asap, but should I recharge the battery before doing so (very low voltage at this point)? And for how long should I take these currents, same 30 minute intervals?
Last edited by soroZ; Jan 20, 2012 at 10:47 PM.