Battery / Alternator Issue

[bauer4567]

So i've been having a little issue. The problem may just be in my head a little bit, but I want to know is anyone else is seeing the same thing...

The other day, on the way home from last minute christmas shopping my truck went dead... well not dead, but the headlights shut off, dash shut off, and the "service battery charging system" displayed on my DIC. I was near home, and was able to get home with a buddy's jumper pack. Ran a load test and found that my alternator was putting out 7-8 volts! NOT GOOD! So the next morning I replaced the alternator and battery. battery was factory, and figured it was about time anyway, even though it still held up under the load test.

So now I have good alternator putting out 14.5 volts +- a little bit, and a battery thats constant at about 12.4 - 12.8 V. However, here is my question.

Everything runs well, haven't had any dimming problems at all, and I have attached a DMM to my cigarette lighter to monitor the levels all the time. With key on, engine off, like I said, I am above 12V. When I start the engine, the DMM shows around 11.8-12 V and the volt gauge on the dash stops at what appears to be around 11-12 volts. I can let it sit like that, no problem. However, then when I start driving, or rev the engine above approximately 2k RPM, the volt gauge on the dash and the DDM jump up to the output of the alternator at around 14 - 14.5...

I guess my dilemma is that I never remember the volt gauge sticking at this roughly 12 volts before I revved the engine or starting driving. Its almost like the alternator doesnt kick on until the engine gets kicked up to 2k...

I have done quite a bit of research, and understand the whole "generator battery monitor" theory, and have checked ALLLL cables for good ground, good contact, and checked the mega fuse mounted to the firewall.

What else could be wrong, or does anyone else have this same quirk in their truck??

The only reason it is bothering me is because I don't think it did this before, as far as I can remember, the voltage gauge always showed roughly 14-15 volts right at start up...

Any advice/help would be appreciated!

EDIT: It does this on cold starts. Its garage kept at night, and will do it in the morning, and then after its parked for long periods of time outside in the cold. But goes right to the 14-15 range on startup with a warm engine...

 

[doubletapdrew]

There are a couple of service bulletins, not sure if either of these apply. Here's the first one:


#02-06-03-008D: Low Voltage Display on IP Gauge, Lights Dim at Stop Lights, Battery Discharged, No Start, Slow Cranking, Dim Lights at Ilde, Low Generator Output - (Jul 21, 2008)


Subject: Low Voltage Display on IP Gauge, Lights Dim at Stop Lights, Battery Discharged, No Start, Slow Cranking, Dim Lights at Idle, Low Generator Output
Models: 1990-2009 GM Passenger Cars and Light Duty Trucks (including Saturn)
2003-2009 HUMMER H2, H3
2005-2009 Saab 9-7X

________________________________________
This bulletin is being revised to add the 2009 model year. Please discard Corporate Bulletin Number 02-06-03-008C (Section 06 -- Engine).
________________________________________
Any vehicle may have a low voltage display (if equipped with gauges), lights that dim at stop lights, slow cranking, no start, low generator output at idle or dim lights at idle when electrical loads are heavy at idle or under slow driving or infrequent usage conditions. These characteristics may be more noticeable with customer added electrical accessories, or with a discharged battery. These are normal operating characteristics of a vehicle electrical system and no repairs should be attempted unless a proven fault has been diagnosed.
During normal driving conditions, when engine speed is above 1000 RPM, the generator is designed to do two things:
• Supply the current necessary to operate the vehicle's originally equipped electrical devices (loads).
• Recharge/maintain the battery's state of charge.
The following factors may affect generator and battery performance:
• Non-usage of the vehicle for extended periods of time. The vehicle's computers, clocks and the like will cause the battery state of charge to drop (For example; 30 days in a parking lot and the vehicle may not start because of a dead battery or a vehicle which is driven only a short distance once a week may end up with a discharged battery to the point where the vehicle may not start). This would be considered abnormal usage of the vehicle and the normally expected result for the vehicle battery, generator and electrical systems.
• At idle, vehicle electrical loads may exceed the low speed current (amperage) output of the generator and when this happens the shortfall comes from the battery. This will result in a drop in the electrical system voltage as the battery delivers the additional electrical current to meet the demand. This is equivalent to the brown outs experienced by homes and businesses when the electrical demand is more than the supply. See Figure 1.
• Extended periods of engine idling, with high electrical loads, may result in a discharged battery. Attempting to recharge a battery by letting the engine run at idle may not be beneficial unless all electrical loads are turned "OFF".
• Increased internal generator temperatures from extended idling can also contribute to lower electrical system voltage. As the generator's internal temperature rises, the generator's output capability is reduced due to increased electrical resistance.
The following are some typical examples of electrical loads:
System Amperage Load
Rear Window Defogger 25
Electric AIR Pump 25
Heated Seats 5 Amps per seat
Headlamps (high) 20
Blower Motor (High) 20
Headlamps (Low) 15
Brake Lights 6
Windshield Wipers 6
Ignition 6

Figure 1



Depending on the vehicle application, generator current (amperage) output at engine idle speeds of 600-700 RPM can be as low as 35 percent of the full rated output. With enough electrical loads "ON", it is easy to exceed the generator current (amperage) output when the engine is at an idle of 600-700 RPM. This is a normal condition. The battery supplements for short periods of time. Items that affect the vehicle's electrical system current and voltage at idle are the number of electrical loads being used, including add-on accessories, and extended idle times. When the vehicle speed is above approximately 24 km/h (15 mph), the engine/generator RPM is high enough and the generator current (amperage) output is sufficient to supply the current (amperage) requirements of the vehicle as originally equipped and recharge the battery.
Dimming lights at idle may be considered normal for two reasons:
1. As the engine/generator speed changes, so will the current (amperage) output of the generator. As a vehicle slows, engine/generator RPM slows and the current (amperage) output of the generator may not be sufficient to supply the loads, the vehicle system voltage will drop and the lights will dim. Dimming of the lights is an indication that current is being pulled from the battery. If the battery is in a low state-of-charge (discharged condition), the driver will notice a more pronounced dimming than a vehicle with a fully charged battery.
2. When high current loads (blower, rear defogger, headlamps, cooling fan, heated seats, power seats, electric "AIR" pump, or power windows) are operating or cycled "ON", the generator's voltage regulator can delay the rise in output. This effect, usually at lower engine speeds, can take up to ten seconds to ramp up the generator output. This is done to avoid loading the engine severely. To increase current (amperage) output, additional torque is consumed by the generator. The engine computer (ECM/PCM) will ramp up engine/generator speed in small steps so engine speed variations are not noticeable to the driver.
For diagnosis of the battery and/or the generator, refer to the appropriate Service Information (SI) or Corporate Bulletin Number 05-06-03-002C.

 

[doubletapdrew]

Here is the second, an alternator recall:

#10117A: Product Safety - Voltage Regulator Internal Low Resistance Short - (Jul 14, 2010)

Condition
Remy, who supplies generators to GM, has decided that a defect, which relates to motor vehicle safety, exists in certain 145 amp generator. Some GM vehicles may have been serviced with these generators. These generators may develop a low resistance short within the voltage regulator. If this occurs, an open circuit could be created which would illuminate the generator lamp in the instrument panel, or in some cases, cause an engine compartment fire.

Correction
Dealers are to inspect and, if necessary, replace the generator.

Dealers who have ordered the involved components for service have been identified in the report that accompanied the dealer message announcing this recall. Identified dealers are to search their part sales records to determine the name and address of the purchaser(s). If the purchaser is the owner of the vehicle, dealers/retailers are to send the owner a copy of the appropriate letter found in this bulletin requesting that their vehicle be brought in for repair. If the purchaser is a body shop, independent repair shop, etc., dealers are to contact the repair facility and obtain the owner's name and address so the dealer can send the owner a copy of the letter.

Vehicles Involved
Involved are certain GM vehicles that were serviced with a replacement 145 amp generator and generators that were sold over-the-counter.

For dealers with identified involved vehicles, a listing with involved vehicles containing the complete vehicle identification number, customer name, and address information has been prepared and will be provided to US and Canadian dealers through the GM GlobalConnect Recall Reports, or sent directly to export dealers. Dealers will not have a report available if they have no identifiable involved vehicles currently assigned.

Dealers that have ordered involved parts for service will be identified in the report contained in the dealer message announcing this recall.

The listing may contain customer names and addresses obtained from Motor Vehicle Registration Records. The use of such motor vehicle registration data for any purpose other than follow-up necessary to complete this recall is a violation of law in several states/provinces/countries. Accordingly, you are urged to limit the use of this report to the follow-up necessary to complete this recall.

Parts Information
Generators required to complete this recall are to be obtained from General Motors Customer Care and Aftersales (GMCC&A). Order the appropriate generator as needed. Please note that only vehicles that do not pass the generator date code inspection will require parts . Orders should be placed as CSO3 = Customer Special Order Advisory Code 3. This will allow orders to write directly to your Admin PDC. If your Admin PDC does not have inventory it will then automatically refer to a distribution center with inventory for next day delivery.

Service Procedure
Only the generator part numbers listed below are involved in this recall.

• 15263859

• 15845338

• 15847291

• 94665498





Generator Build Date Location is at the 11 o’clock position on gasoline engines and at the 2 o’clock position for diesel engines. (1) Gasoline Engine Generator Build Date Location shown.

Note: The first character in the date code identifies which plant that the generator was built. The next two digits are for the day of month the generator was built. The next two characters are for the month that the generator was built. The next two digits are for the year that the generator was built. The last character is for the production cell and shift. An example date code is M 13 DE 10 A. The plant is Mexico. The day of the month is 13, the month is December, and the year is 2010. The production cell and shift is A.

Note: If the vehicle is equipped with an auxiliary generator, INSPECT the generator build date to determine if it must be replaced.

Determine the part number and build date of the generator. Record the build date on the repair order. Refer to the illustration for build date location.
• For P/N 15263859:

- If the generator build date is January 5, 2010 or later, remove the generator and replace it with a new one; proceed to Step 2.

- If the generator build date is BEFORE January 5, 2010, replacement of the generator is NOT required. No further action is required.

• For P/N 15845338

- If the generator build date is January 11, 2010 or later, remove the generator and replace it with a new one; proceed to Step 2.

- If the generator build date is BEFORE January 11, 2010, replacement of the generator is NOT required. No further action is required.

• For P/N 15847291:

- If the generator build date is January 5, 2010 or later, remove the generator and replace it with a new one; proceed to Step 2.

- If the generator build is BEFORE January 5, 2010, replacement of the generator is NOT required. No further action is required.

• For P/N 94665498:

- If the generator build date is December 19, 2009 or later, remove the generator and replace it with a new one; proceed to Step 2.

- If the generator build date is BEFORE December 19, 2009, replacement of the generator is NOT required. No further action is required.

Remove the generator and auxiliary generator, if required, from the vehicle. Refer to the appropriate Generator Replacement and/or Auxiliary Generator Replacement in SI.
Install the new generator. Refer to the appropriate Generator Replacement and/or Auxiliary Generator Replacement in SI.
Claim Information
1. Submit a claim using the table below.

Labor Operation
Description
Labor Time

For Vehicles That Are Listed in GWM

V2294
Gas Engine - Inspect Date Code - No Repair Required - Record Build Date of Generator in the Correction Description field when submitting claim
0.2

V2295
Diesel Engine - Inspect Date Code - No Repair Required - Record Build Date of Generator in the Correction Description field when submitting claim
0.3

V2296
Inspect Date Code & Replace Generator - Record Build Date of Generator in the Correction Description field when submitting claim
*

For Vehicles That Are Not Listed in GWM But Have Been Serviced With a Suspect Generator

T5776
Record Search for Owner Name & Address - Time Allowance Includes Time Searching for Purchaser's Name and Address & Expense Incurred Mailing the Owner Letter
**

T5777
Gas Engine - Inspect Date Code - No Repair Required - Record Build Date of Generator in the Correction Description field when submitting claim
0.2

T5778
Diesel Engine - Inspect Date Code - No Repair Required - Record Build Date of Generator in the Correction Description field when submitting claim
0.3

T5779
Inspect Date Code & Replace Generator - Record Build Date of Generator in the Correction Description field when submitting claim
*


* Submit appropriate published time found in the Labor Time Guide for the generator replacement plus the inspection time of 0.2 labor time for gas engines, 0.3 for diesel engines.

** After all records have been searched, submit one claim for the total time. The total time should be 0.3 hours times the total number of names and addresses found. This labor code can only be submitted once per dealer.

 

[blueflamed03]

<revised for 2009 models>


wow.....I dont know if I can even trust a new GM vehicle anymore......scared to buy NEW....

 

[bauer4567]

Had it at the dealer all day. They say nothing is wrong (only does it on a cold start). They say that because I used the 145 amp alternator instead of the 160 amp, this is my problem. They are liars, and want $660 to replace.

I have a factory reman coming tomorrow (160 amp), so I will see. I really want to strangle that little sh**head at the dealer. I hate how they talk so condescending, when I know as well as the next guy that if my DMM is showing 11 volts, it makes no f-in difference how many AMPS the alternator is putting out. Then as soon as I rev it, the gauge reads properly, and it sits at 13.2-14 when idling...

 

[jstahoe]

My truck is having kinda something similar....when I go to start it, it acts like a i got a dead battery. After a few trys of turning my key it starts up, but my voltmeter reads normal about 14v after it starts. I just posted a thread but my chevy dealer guy said my battery reads 100% charge. So keep us posted if you get anything on your truck. So i feel your pain!!!!!

 

[stevek]

Because the belts in the engine spin faster when you're in motion (or above idle) hence why the meter reads 14v. That's normal. The meter on your instrument cluster isn't accurate to say the least. Maybe install a different pulley on your alt.

 

[doubletapdrew]

What battery did you replace it with? Factory? The factory battery is garbage and barely adequate for the stock electronics, I think it's like 500cca or 550 or something. Mine was having cold starting issues recently and I replaced it with the battery for the diesel pickups which are something like 800cca.

 

[jcrack_corn]

your truck is behaving normally.

this has been addressed numerous times.

 

[bauer4567]

your truck is behaving normally.

this has been addressed numerous times.

No. The fluctuation of voltage has been addressed numerous times... That is not what I was talking about.

I put the Duralast gold in. The dealer had it yesterday, reprogrammed the BCM, and now the voltage goes up to 14 at startup/idle without a quick rev. Before, all I had to do was touch the gas, and then it would go back to idle, but be charging full. Only at start up without touching the gas would it be stuck at the 11-12 volts (thats with a DMM, not the volt meter on the dash...

Anyway, so far so good since the BCM...