redboy

Alt. putting out 15.52v and battery looks like its wet from boiling I guess.How do I tell if its the alternator or could it be the battery causing the hi rate of charge? Appreciate some help

Scrufdog

Thats the alternator. A battery can not force an alternator to go that high with voltage.

redboy

Thanks for the answer,unfortionatally for me......

tech2

what year truck...as the voltage regulator may be ecm controlled

redboy

07 sub,if its ecm controled,what then?

redboy

ok, I appreciate the help,guess I should start over,I have a 07 suburban,5.3 vin#1gnfk16377j208156 , 83000 mi.I changed battery,now charging under 15 ,so I changed alternator and now it charges more,so I put old one back on.Tech mentioned it might be ecm controled,guess I have to take to dealer now,any suggestions?

73shark

Voltage regulation is controlled by the ECM on the GMT900s.

You will need to have it checked out by a dealer.

redboy

thank you,are they able to reprogram ecm,or does that meen I have to buy new ecm? If so how much do they run?

tech2

this is straight from the description and operation
The BCM will enter Charge Mode when ever one of the following conditions are met.

• The wipers are ON for more than 3 seconds.
• GMLAN (Climate Control Voltage Boost Mode Request) is true, as sensed by the HVAC control head. High speed cooling fan, rear defogger and HVAC high speed blower operation can cause the BCM to enter the Charge Mode.
• The estimated battery temperature is less than 0°C (32°F).
• Battery State of Charge is less than 80 percent.
• Vehicle Speed is greater than 145 kph (90 mph)
• Current Sensor Fault Exists
• System Voltage was determined to be below 12.56 volts
• Tow/Haul Mode is enabled

When any one of these conditions is met, the system will set targeted generator output voltage to a charging voltage between 13.9–15.5 volts, depending on the battery state of charge and estimated battery temperature.
------------------------------
Was the battery warm to the touch?

in2pro

lol, guessing one of the Corvette team guys was walking past the Tahoe/burb guys cube on that "feature" design day.... my Tahoe has seen 90+ mph, but we are talking seconds at a time...but I guess with posted speed limits of 85mph, 90mph for extended periods of driving is possible...