whats the difference between a 04 alt and 06 alt? the 04 has three wires and the 06 has 2 wires. the 04 has blue brown and grey and the 06 has brown and grey.

 

hmm, i haven't noticed that. I'm about to do an engine swap so i hope there's no difference. I would like to know too.

 

my buddy is taking a 4.3l out of an 06 and installing a 5.3l. the alt's ar different. so were trying to figure out if he can just pin the plug with the grey and brown wires and leave out the blue. maybe its just a wire that keeps checks on the alt. if so we can just disable that code.

 

somebody has to know something...........thanks for posting it up mike.

 

The extra wire is used on trucks with SBA(supplemental brake assist).

 

what is supplemental brake assist? does that have to do with my hydroboost brakes?

 

No, you are good to go if you have Hydroboost.

"Supplemental Brake Assist
The Supplemental Brake Assist (SBA) unit creates vacuum for the brake booster in case of a vacuum loss or low vacuum to the brake booster. The SBA consists of

• The sensor circuit board and pressure sensor
• The check valve manifold
• The vacuum pump
• The motor

When the vehicle is keyed ON, the SBA performs a self test by toggling the Supplemental Brake Assist Signal Circuit low for one second. The instrument panel cluster (IPC) recognizes this as an indication that the SBA is functional. If the IPC does not see this signal for five consecutive ignition cycles the Service Brake Booster Message is displayed. The SBA performs diagnostics at 16 Km/h (10 mph) under normal conditions, and before 16 Km/h (10 mph) if a low vacuum condition exists. The SBA then spins the motor and runs diagnostics to determine if the pump is operating and the SBA is functional. The SERVICE BRAKE BOOSTER message will display until the next ignition cycle if the unit is unable to maintain reduced power brake levels.
The SBA unit utilizes the ignition on signal from the generator to determine the engine is running and monitors speed using an input from the vehicle speed sensor. It also has an internal pressure sensor that compares the pressure inside the booster to the ambient pressure. If the vacuum drops below 18 cm/Hg (7 in/Hg) the REDUCED BRAKE POWER message is displayed and a 5 second timer is started. If the vacuum stays below 18 cm/Hg (7 in/Hg) for 5 seconds the SBA starts the pump. If the vacuum drops below 15 cm/Hg (6 in/Hg) the pump comes on immediately. Once the vacuum level increases to 23 cm/Hg (9 in/Hg) The pump shuts off. The REDUCED BRAKE POWER message continues to be displayed until the vacuum level reaches 25 cm/Hg (10 in/Hg). If the pump runs for one minute without the vacuum reaching 23 cm/Hg (9 in/Hg) the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed.
The SBA assembly operates in two modes.

• Low Vacuum Mode -- The low vacuum mode can occur with the engine ON or OFF. The SBA determines the ON/OFF status by monitoring the regulator output on the engine ON circuit. This mode involves SBA pump activation and deactivation due to changes in vacuum detected by the pressure sensor.
  • Low Vacuum Engine ON Mode -- The SBA will operate in reaction to changes to brake booster vacuum as monitored by the pressure sensor. This mode is normally active on power up if a valid engine ON signal is detected and a low vacuum condition is indicated for more than 5 seconds.
  • Reduced Brake Power Mode -- When the booster vacuum drops below 18 cm/Hg (7 in/Hg) the SBA will start a 5 second timer. If the vacuum exceeds 18 cm/Hg (7 in/Hg) the timer stops and resets. After 5 seconds the pump activates and the REDUCED BRAKE POWER message is displayed.
  • Immediate Pump Activation Mode -- When the booster vacuum drops below 15 cm/Hg (6 in/Hg) the REDUCED BRAKE POWER message is displayed and the pump is turned on.
  • Pump Deactivation Mode -- The pump will be turned off when the booster vacuum exceeds 23 cm/Hg (9 in/Hg). The SBA will continue to display REDUCED BRAKE POWER until the booster vacuum exceeds 25 cm/Hg (10 in/Hg).
  • Low Vacuum Engine Off -- The SBA will monitor the vacuum when the vehicle is above 8 Km/h (5 mph) and an engine OFF condition is detected. If the vehicle is below 8 Km/h (5 mph) and an engine OFF condition is detected the SBA will monitor the vacuum for 60 seconds
• Vacuum Augment (Engine OFF) Mode -- If the engine ON state changes to OFF after reaching 8 Km/h (5 mph) the SBA activates the pump for up to 60 seconds. After 60 seconds the pump shuts off and the SERVICE BRAKE BOOSTER message is displayed. If the engine ON signal is detected or the vehicle slows to below 8 Km/h (5 mph) before the pump times out. The pump shuts off and no message is displayed. "

 

ok, my silverado had that. but my alt has 3 wires and i have hydrobost. he got the wire harness off of a 04 silverado so i'm sure it had that. wouldn't an 07 have the SBA also? i'll have mcfarlnd go look. do the newer models have a different eng on signal? i know i have seen snake eaters engine has a thing that looks like a current detector over the alt/bat wires. if the newer models have a different eng on wire then he could hook that where the third wire from the 04 alt goes. does that make sence? did to me lol.

 

I have hydroboost as well and I have the Blue wire- circuit 5668. Which supposedly becomes a Black/White wire at connector C100(under the underhood electrical center) of the I/P harness. But after that there is no further mention of that circuit for my truck. So I doubt there is anything connected to the other end of the Blue wire. On a vac assist truck the Black/White wire is supposed to break out of the I/P harness before the firewall and connect to the SBA pump motor.

 

so if i dont pin the blue wire in ill be good to go right? dr. x where did you get all that info?? thanks for the help.