2006 Pete overcharging

I dont know about this truck, but there are really rivet styled LED. I saw in internet.

 

Your good. You gauge might be a little off.

Same pulley on the alternator as original?

 

internal voltage supply mesurment is a comparation of divided with a pair of resistors supply voltage and 5V logic power supply inside dashboard ore with well stabilized with Zener diode sample voltage.... so the problem is in small SMD resistors indide dashboard ore toasted ore poor soldered Zener diodes. I havent fix Pete dashboards, but I had many voltage metering issues with other control units, like with Temic PLD ECMs on MB engines....

so remove your dashboard and inspect board for corrosion. Corroded operation amplifier, resistors ore zener diodes are sourse of wrong voltage reading and.... you know!

 

Are you sure it is a 5SI, and not a 35SI?
The 5SI is a small 50A unit. 35SI is 100A+.

Using a digital voltmeter what are the following no load measurements at 1500rpm;
Alternator, B+ to B-,
Alternator, Smart Sense to B-,
Alternator, B- to engine block,
Alternator, B- to chassis,
Alternator, B- to cab,
Starter, + to -,
Batteries, + to -.
Please give answers to 2 decimal places, eg 14.26V, 0.13v etc.

Repeat same measurements with all electrical loads on, lights, ac etc.

Where does the Smart Sense wire go to?

What effect does disconnecting the Smart Sense wire have?

What effect does connecting the Smart Sense wire to the alternator B+ terminal have?

 

An open sense wire will cause overcharging.

With the engine off,
remove the smart sense wires.
measure the voltage on both smart sense wires to frame ground.

one wire should measure the battery voltage (12 to 13 volts)
the other should measure 0 or a few tenths at most.

an open batt + will measure 0 or float around (not be steady) and may measure some oddball voltage.

an open neg - may measure some oddball voltage.

TMI
Alternators are almost always set to 13.8volts for output. Sense lines are used to make sure that there is 13.8 volts delivered to the batteries by correcting for any voltage drops across the cable. Internally the sense lines are almost always have a connection to the output terminals that is through a diode. A diode usually has about a .6v drop across it.

When both sense lines are open the voltage at the back of the alternator will rise to about 15 volts. (13.8 + .6 + .6 = 15)

good luck

 

I am with Pablo. I think the alternators and batteries were all good and the dash / body computer was reading incorrectly. Did you ever check the voltage at the batteries with a multimeter to confirm?