Charging system help
Thread Starter
Burning Brakes
Joined: Apr 2003
Posts: 908
Likes: 4
From: TROY MI
Charging system help
My charging system voltage is very erratic.It fluctuates from 11.7 to 14volts.The DIC reads .4 to .6 volts less than the battery. The large red wire on the back of the alternator reads 14.4 volts and the battery volts can read anywhere from 12.5 to 13.7 at idle.I need some help on what to do next.
Racer
Joined: Apr 2009
Posts: 488
Likes: 2
From: Myrtle Beach SC
The DIC commonly reads lower than other indications of battery voltage.
If you have the service manual, look through the diagnostic test procedures beginning on page 6-370. The "load check" (for when the DIC displays the CHARGE SYSTEM FAULT) message is a good test to run.
The diagnostics "section" has at least 30 pages of tests you can run to help pinpoint the concerns you cite in your post.
How old is the battery? Has it ever died on you? What type of battery => lead-acid or gel-type?
If you have the service manual, look through the diagnostic test procedures beginning on page 6-370. The "load check" (for when the DIC displays the CHARGE SYSTEM FAULT) message is a good test to run.
The diagnostics "section" has at least 30 pages of tests you can run to help pinpoint the concerns you cite in your post.
How old is the battery? Has it ever died on you? What type of battery => lead-acid or gel-type?
Thread Starter
Burning Brakes
Joined: Apr 2003
Posts: 908
Likes: 4
From: TROY MI
The DIC commonly reads lower than other indications of battery voltage.
If you have the service manual, look through the diagnostic test procedures beginning on page 6-370. The "load check" (for when the DIC displays the CHARGE SYSTEM FAULT) message is a good test to run.
The diagnostics "section" has at least 30 pages of tests you can run to help pinpoint the concerns you cite in your post.
How old is the battery? Has it ever died on you? What type of battery => lead-acid or gel-type?
If you have the service manual, look through the diagnostic test procedures beginning on page 6-370. The "load check" (for when the DIC displays the CHARGE SYSTEM FAULT) message is a good test to run.
The diagnostics "section" has at least 30 pages of tests you can run to help pinpoint the concerns you cite in your post.
How old is the battery? Has it ever died on you? What type of battery => lead-acid or gel-type?
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
The usual causes of erratic battery readings are lose cables/connections. Verify that both battery connections are clean and properly tightened. Then get under there and check the battery connection at the starter solenoid which is where the alternator also connects. The negative battery cable should attach to the block down there. Now Bill Curlee posted about his having this issue and he's got pictures of a ground wire that connects to the frame just between the engine compartment fuse box and the battery, down low in there, so you might want to check on it for cleanliness and tightness.
Thread Starter
Burning Brakes
Joined: Apr 2003
Posts: 908
Likes: 4
From: TROY MI
The usual causes of erratic battery readings are lose cables/connections. Verify that both battery connections are clean and properly tightened. Then get under there and check the battery connection at the starter solenoid which is where the alternator also connects. The negative battery cable should attach to the block down there. Now Bill Curlee posted about his having this issue and he's got pictures of a ground wire that connects to the frame just between the engine compartment fuse box and the battery, down low in there, so you might want to check on it for cleanliness and tightness.
Should the red wire on the back of the altenator always read 14.4 volts?
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Yes, since its connected to the battery at the starter solenoid assuming the engine is running of course otherwise it should read the battery static voltage.
Thread Starter
Burning Brakes
Joined: Apr 2003
Posts: 908
Likes: 4
From: TROY MI
Yes it does read the battery voltage with the engine off.If I am reading 14.4 volts with the engine running and I am only getting 12.7 volts(it varies I get 13.xx at times also) at the battery then I must have a bad solenoid/connection. Does this sound right?
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Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
You should see the exact same voltages at the starter solenoid when the car is running or not. If there is a difference, alternator has 14.4 coming out of it but the battery is showing 13.4 for example, then you need to look at the connections at the starter solenoid. That solenoid is the electrical center of the car. Its where the power input and outputs all come together therefore those connections must be clean and tight. Look for evidence of browned insulation on any of the cables there which would indicate a resistive connection, therefore heat being generated and resulting in the burning/heating of the insulation. Do not make the mistake of forgetting that this is all electrically hot down there as you have a direct connection to the battery. Make sure you disconnect the negative cable from the battery before making any changes down there.
Tech Contributor
Joined: Dec 2006
Posts: 10,962
Likes: 29
From: Van Buren Arkansas
Wounded Warrior Escort '11
Also, I'm referring to this measurements using a DVM (Digital Volt Meter). If you are relying on DIC display of the battery voltage, look at that ground wire I mentioned before.
Thread Starter
Burning Brakes
Joined: Apr 2003
Posts: 908
Likes: 4
From: TROY MI
You should see the exact same voltages at the starter solenoid when the car is running or not. If there is a difference, alternator has 14.4 coming out of it but the battery is showing 13.4 for example, then you need to look at the connections at the starter solenoid. That solenoid is the electrical center of the car. Its where the power input and outputs all come together therefore those connections must be clean and tight. Look for evidence of browned insulation on any of the cables there which would indicate a resistive connection, therefore heat being generated and resulting in the burning/heating of the insulation. Do not make the mistake of forgetting that this is all electrically hot down there as you have a direct connection to the battery. Make sure you disconnect the negative cable from the battery before making any changes down there.
Drifting
Joined: May 2008
Posts: 1,517
Likes: 319
From: Hewitt TX
Yep, I think I may have just fixed my Charge System Fault P1637 code. My fingers are crossed!. On a whim I replaced the Optima Red Top with the Sears Die Hard Gold and I have yet to have the code thrown. I ran a few errands around town this afternoon and never got the code where as I would get it every start. Also, I noticed I now see a pretty steady 14.1 Volts on my DIC where I use to only see 13.5 to 13.6. Hopefully this was the fix for me. I was really hoping I didnt have to pull the right side Long tube off to get to the started. So like I said FINGERS CROSSED!
