low voltage while driving
Thread Starter
Instructor
Joined: Jul 2005
Posts: 137
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From: Berlin New Jersey
low voltage while driving
98 C5 Coupe
Intermittent Charging System Fault when starting. Changed to brand new yellow top optima. still had intermittent Charging System Fault when starting. The voltage starting going high on my gauge then low while driving the other day. I had my GM alternator rebuilt. Started and no charging system fault. Drove about 10 miles and it starting coming on while driving over and over and volts went down to 12. Pulled over and all of a sudden, went back up to 13.5-13.8. What can I do?
I am afraid to even drive it. Starting is fine, AC works, lights work, radio works. The only problem I had prior to this happening was my horn went off in the middle of the night and I pulled the horn fuse. Thoughts?????
Intermittent Charging System Fault when starting. Changed to brand new yellow top optima. still had intermittent Charging System Fault when starting. The voltage starting going high on my gauge then low while driving the other day. I had my GM alternator rebuilt. Started and no charging system fault. Drove about 10 miles and it starting coming on while driving over and over and volts went down to 12. Pulled over and all of a sudden, went back up to 13.5-13.8. What can I do?
I am afraid to even drive it. Starting is fine, AC works, lights work, radio works. The only problem I had prior to this happening was my horn went off in the middle of the night and I pulled the horn fuse. Thoughts?????
Pro
Joined: Jun 2005
Posts: 593
Likes: 1
I would check for loose or bad battery cables or loose ground splice. One ground is right on frame below battery, another by starter and then another main one is on the left rear of engine has a ground strap going to left frame.
A stuck relay, use all functions like seats, mirrors, anything that is controlled and see if some relay is sticking.
If none of is the problem a loose belt would not allow alt to spin enough.
Lastly since the PCM commands to the ALT when to raise or lower alt output maybe bad or dirty PCM connector pins and worse case PCM has a internal problem
If horn stuck on could be it has a bad relay
A stuck relay, use all functions like seats, mirrors, anything that is controlled and see if some relay is sticking.
If none of is the problem a loose belt would not allow alt to spin enough.
Lastly since the PCM commands to the ALT when to raise or lower alt output maybe bad or dirty PCM connector pins and worse case PCM has a internal problem
If horn stuck on could be it has a bad relay
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
You have a loose or dirth ground somewhere! There is also one very large engine ground down next to the starter! That one has a tendancy to come loose and or get corroded! Also make sure that the wires, plugs and connections on the alternator are clean and tight!!PLEASE let us know how you make out!!
BC
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
Jack up the passengers side, put it on jack stands, remove the wheel, and the starter is on the rear section of the engine block. The ground lug is above the front of the starter on the side of the block. If memory serves me correctly it is a 15mm bolt! It will be difficult to get to but not impossible.
The battery to frame ground is here:
I will look for other grounds or electrical connections that you should check a little later tonight. I have to go seal the (burnout strip for the Z06
) I mean,,, driveway!
BC
The battery to frame ground is here:
I will look for other grounds or electrical connections that you should check a little later tonight. I have to go seal the (burnout strip for the Z06
) I mean,,, driveway! BC
Race Director
Joined: Jul 2005
Posts: 11,308
Likes: 1
From: The Beautiful Greater Bay Area California
Originally Posted by Bill Curlee
You have a loose or dirth ground somewhere! There is also one very large engine ground down next to the starter! That one has a tendancy to come loose and or get corroded! Also make sure that the wires, plugs and connections on the alternator are clean and tight!!PLEASE let us know how you make out!!
BC
