High bias current
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 26
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High bias current
Dear all
I have a C5 corvette from 1998. My problem is that the battery is empty after two days - the battery is new.
I measured the current after about 15 minutes when everything has shut down. The result is that the bias current is 370mA which is by far too high.
In the sleeping mode of the car I have taken out fuse by fuse but couldn't find any device so that the bias current would go to below 100mA.
Do you have any idea what could cause this high bias current?
The only relevant code was TCS C1225 that is historic - I have no problems with ABS or so. I assume that this code is from pulling the fuses.
Thanks for your help.
Cheers
Andreas
I have a C5 corvette from 1998. My problem is that the battery is empty after two days - the battery is new.
I measured the current after about 15 minutes when everything has shut down. The result is that the bias current is 370mA which is by far too high.
In the sleeping mode of the car I have taken out fuse by fuse but couldn't find any device so that the bias current would go to below 100mA.
Do you have any idea what could cause this high bias current?
The only relevant code was TCS C1225 that is historic - I have no problems with ABS or so. I assume that this code is from pulling the fuses.
Thanks for your help.
Cheers
Andreas
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
On your UNDER HOOD FUSE BOX, there is a B+ terminal. On that terinal, are TWO connections. Disconnect the battery, remove the NUT securing the connections to the fuse box. find a spare nut and bolt and make a temporary connection with the TWO cable that you removed from the fuse box stud.
That will allow you to only power up the passengers foot well fuse box and the alternator. (REMEMBER!!! The alternator is always powered because it gets it power from the battery through the starter solenoid)
With the eng compartment fuse box completely isolated, take a SLEEP CURRENT reading and report the findings.
You can also place the AMP meter in series with the ALTERNATOR BATT Terminal on the back of the alternator. It should read ZERO AMPS. If it doesn't, the bridge rectifier in the alternator is bad.
Some things that I would UN-PLUG to take out of the circuit:
Drivers seat electrical connector under the seat.
Check all that out and see what you find.
BC
That will allow you to only power up the passengers foot well fuse box and the alternator. (REMEMBER!!! The alternator is always powered because it gets it power from the battery through the starter solenoid)
With the eng compartment fuse box completely isolated, take a SLEEP CURRENT reading and report the findings.
You can also place the AMP meter in series with the ALTERNATOR BATT Terminal on the back of the alternator. It should read ZERO AMPS. If it doesn't, the bridge rectifier in the alternator is bad.
Some things that I would UN-PLUG to take out of the circuit:
Drivers seat electrical connector under the seat.
Check all that out and see what you find.
BC
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 26
Likes: 0
On your UNDER HOOD FUSE BOX, there is a B+ terminal. On that terinal, are TWO connections. Disconnect the battery, remove the NUT securing the connections to the fuse box. find a spare nut and bolt and make a temporary connection with the TWO cable that you removed from the fuse box stud.
That will allow you to only power up the passengers foot well fuse box and the alternator. (REMEMBER!!! The alternator is always powered because it gets it power from the battery through the starter solenoid)
With the eng compartment fuse box completely isolated, take a SLEEP CURRENT reading and report the findings.
You can also place the AMP meter in series with the ALTERNATOR BATT Terminal on the back of the alternator. It should read ZERO AMPS. If it doesn't, the bridge rectifier in the alternator is bad.
Some things that I would UN-PLUG to take out of the circuit:
Drivers seat electrical connector under the seat.
Check all that out and see what you find.
BC
That will allow you to only power up the passengers foot well fuse box and the alternator. (REMEMBER!!! The alternator is always powered because it gets it power from the battery through the starter solenoid)
With the eng compartment fuse box completely isolated, take a SLEEP CURRENT reading and report the findings.
You can also place the AMP meter in series with the ALTERNATOR BATT Terminal on the back of the alternator. It should read ZERO AMPS. If it doesn't, the bridge rectifier in the alternator is bad.
Some things that I would UN-PLUG to take out of the circuit:
Drivers seat electrical connector under the seat.
Check all that out and see what you find.
BC
Hi Bill
Great. Thanks for your advice. I will do this at the weekend - I have no time before.
Cheers
Andreas
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 26
Likes: 0
[QUOTE=c5-ch;1589805404]
Hi Bill
I isolated the top and then the lower fuse box. This way I finally found the fuse that led to an almost zero sleeping current. It is the fuse No 25 in the passenger fuse box.
It says that this is the fuse for BCMI & IPC. It seams that this is related to the instrument panel. Do you have any idea what the problem could be and how to resolve it?
Thanks a lot for your kind support.
Best regards,
AS
Hi Bill
I isolated the top and then the lower fuse box. This way I finally found the fuse that led to an almost zero sleeping current. It is the fuse No 25 in the passenger fuse box.
It says that this is the fuse for BCMI & IPC. It seams that this is related to the instrument panel. Do you have any idea what the problem could be and how to resolve it?
Thanks a lot for your kind support.
Best regards,
AS
Le Mans Master
Joined: Mar 2011
Posts: 6,835
Likes: 302
From: Columbia SC
It seems like the BCM is still controlling something that it should not.
With fuse 25 in try seeing if any relays are warm after a while. Have you tried pulling any more fuses after you found that one? Any such checking should have fuse 25 in.
370 ma is not real high. Make sure it is not a light somewhere or the radio, etc.
With fuse 25 in try seeing if any relays are warm after a while. Have you tried pulling any more fuses after you found that one? Any such checking should have fuse 25 in.
370 ma is not real high. Make sure it is not a light somewhere or the radio, etc.
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 26
Likes: 0
It seems like the BCM is still controlling something that it should not.
With fuse 25 in try seeing if any relays are warm after a while. Have you tried pulling any more fuses after you found that one? Any such checking should have fuse 25 in.
370 ma is not real high. Make sure it is not a light somewhere or the radio, etc.
With fuse 25 in try seeing if any relays are warm after a while. Have you tried pulling any more fuses after you found that one? Any such checking should have fuse 25 in.
370 ma is not real high. Make sure it is not a light somewhere or the radio, etc.
Thanks a lot for your help.
I have pulled all fuses and even the relays. It was the only one causing a jump down to almost zero sleeping current. touching the relays with my fingers seems not to give any indication that one of them is warm - they seem all to be a cold as the air.
I have checked all lights and also the **** on the left to change the light in the instrument panel. I also turned off the cruise control.
Just to make sure I checked all the functions of the car and it seems that everything works fine.
Is there anything you would disconnect (e.g. seats) in order to test more?
Thanks a lot for your kind support.
Best regards,
Andreas
Thread Starter
Intermediate
Joined: Jun 2009
Posts: 26
Likes: 0
Dear Bill
Thanks a lot for your help.
I have pulled all fuses and even the relays. It was the only one causing a jump down to almost zero sleeping current. touching the relays with my fingers seems not to give any indication that one of them is warm - they seem all to be a cold as the air.
I have checked all lights and also the **** on the left to change the light in the instrument panel. I also turned off the cruise control.
Just to make sure I checked all the functions of the car and it seems that everything works fine.
Is there anything you would disconnect (e.g. seats) in order to test more?
Thanks a lot for your kind support.
Best regards,
Andreas
Thanks a lot for your help.
I have pulled all fuses and even the relays. It was the only one causing a jump down to almost zero sleeping current. touching the relays with my fingers seems not to give any indication that one of them is warm - they seem all to be a cold as the air.
I have checked all lights and also the **** on the left to change the light in the instrument panel. I also turned off the cruise control.
Just to make sure I checked all the functions of the car and it seems that everything works fine.
Is there anything you would disconnect (e.g. seats) in order to test more?
Thanks a lot for your kind support.
Best regards,
Andreas
I checked again the temperature of the relays after the car has been parked for 2 hours. And this time indeed relay No 37 which is Monitored LD was warm. I took it out and opened it. Not much to see.
Do you know where I best buy a new relay?
Thanks for your help.
Andreas
Tech Contributor
Joined: Dec 1999
Posts: 32,910
Likes: 2,402
From: Anthony TX
CI 6,7,8,9,11 Vet
St. Jude Donor '08
I believe its a dealer part. Check all of your local autoparts stores first.. Especially NAPA...
If they dont have it, Gene Culley will...
http://www.cultragfactoryparts.com/
Bill
If they dont have it, Gene Culley will...
http://www.cultragfactoryparts.com/
Bill
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Thread Starter
Intermediate
Joined: Jun 2009
Posts: 26
Likes: 0
Bill
I checked again the temperature of the relays after the car has been parked for 2 hours. And this time indeed relay No 37 which is Monitored LD was warm. I took it out and opened it. Not much to see.
Do you know where I best buy a new relay?
Thanks for your help.
Andreas
I checked again the temperature of the relays after the car has been parked for 2 hours. And this time indeed relay No 37 which is Monitored LD was warm. I took it out and opened it. Not much to see.
Do you know where I best buy a new relay?
Thanks for your help.
Andreas
I did the following check: all the fuses are in and I let the car go "to sleep". The current was again 370mA. Then I removed the relay 37 but this had no effect on the sleeping current. Should the current not go down if I pull relay 37? (I let fuse 25 in)
Therefore I am not sure whether it is really the relay 37 that is broken.
Thanks for your help.
Best
Andreas