Brake booster service - 2005 Chevrolet Tahoe

Question edited for clarity.
Question moved to model category.

There are some diagrams here, but not very clear.

https://www.google.com/search?q=nissan+pathfinder+brake+booster+hose+diagram

Service Manuals

https://www.google.com/search?q=nissan+pathfinder+brake+booster+hose+diagram

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SERVICE BRAKE BOOSTER
Refer to Brake Warning System Description and Operation in Hydraulic Brakes

SERVICE BRAKE BOOSTER
The SERVICE BRAKE BOOSTER message will be displayed when the supplemental brake assist signal circuit is toggled at 1.0 Hz with a 50 percent duty cycle. This message is also displayed if the instrument panel cluster (IPC) does not see an alive and well signal at key on. When this message is displayed it indicates a problem with the SBA and should be serviced or replaced.

How do the power brakes work ? Good .?

Service Brake Booster Message Displayed
Step
Action
Yes
No
Schematic Reference: Brake Warning System Schematics
1
Did you review the Brake Warning System Description and Operation and the Brake Assist System Description and Operation and perform the necessary inspections?
YES - Go to Step 2
NO - Go to Symptoms - Hydraulic Brakes
2
Start the vehicle.
Is the REDUCED BRAKE POWER message displayed for 1 minute before the SERVICE BRAKE BOOSTER message is displayed?
YES - Go to Step 3
NO - Go to Step 4
3
Perform the Brake Assist System Diagnosis
Did you find and correct the condition?
YES - Go to Step 12
NO - Go to Step 11
4
Disconnect the Supplemental Brake Assist connector.
Test the ignition 1 circuit for an open or a short to ground.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
YES - Go to Step 12
NO - Go to Step 5
5
Test both ground circuits for opens.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
YES - Go to Step 12
NO - Go to Step 6
6
Test the engine on signal circuit for an open or a short to ground.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
YES - Go to Step 12
NO - Go to Step 7
7
Test the vehicle speed signal circuit for an open.
Did you find and correct the condittion?
YES - Go to Step 12
NO - Go to Step 8
8
Test the supplemental brake assist signal circuit for an open or a short to voltage.
Refer to Circuit Testing and Wiring Repairs in Wiring Systems.
Did you find and correct the condition?
YES - Go to Step 12
NO - Go to Step 9
9
Connect the supplement brake assist connector.
Disconnect the instrument panel cluster connector.
Connect a DMM from battery positive voltage to the supplemental brake assist signal circuit.
Turn the ignition to the RUN position while observing the DMM.
Did the DMM flash battery voltage?
YES - Go to Step 11
NO - Go to Step 10
10
Replace the Supplemental Brake Assist pump motor assembly Refer to Power Brake Booster Auxiliary Pump Replacement .
Did you complete the replacement?
YES - Go to Step 12
--
11
Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument Panel, Gages and Console.
Did you complete the replacement?
YES - Go to Step 12
--
12
Start the engine.
Does the Service Brake Booster message stay on?
Go to Step 2
System OK

Adjust the brake pedal pushrod so there is a small clearance or free play in the brake pedal linkage equivalent to a couple of millimetres of free play on the pedal.

It is then extremely important to ensure there is a clearance of about 0.010" between the brake master cylinder piston and the booster pushrod. In the absence of the official service tool some careful measuring will be required. Some boosters have an adjustable pushrod and some need shims to be inserted between the booster and cylinder and some manufacturers provide no facility for adjustment...

you must have a vacuum leak at booster or the line going to it. This will cause engine to not start and no power brakes (hard pedal).

here you go...

The power brake booster is a tandem vacuum suspended unit. Some models may be equipped with a single or dual function vacuum switch which activates a brake warning light should low booster vacuum be present. Under normal operation, vacuum is present on both sides of the diaphragms. When the brakes are applied, atmospheric air is admitted to one side of the diaphragms to provide power assistance.
REMOVAL & INSTALLATION

1994-97 Models
See Figures 1 and 2

1. Apply the parking brake and block the drive wheels.
2. Remove the master cylinder-to-power brake booster nuts, then reposition the master cylinder and combination valve out of the way; if necessary, support the master cylinder on a wire to prevent damaging the brake lines.

When removing the master cylinder from the power brake booster, it is not necessary to disconnect the hydraulic lines, therefore the brake system should not have to be bled.

1. Disconnect the vacuum hose from the power brake booster.

Fig. Fig 1: Common power brake booster attachment

1. From under the dash, remove the retainer and washer from the brake pedal on 1994 utility models. On all other models, remove the retainer and brake switch from the brake pedal.
2. Disconnect the pushrod from the brake pedal.
3. From under the dash, remove the power brake booster-to-cowl retaining nuts.
4. Back under the hood, remove the power brake booster and the gasket from the cowl.

To install:

1. Position the booster to the cowl using a new gasket.
2. Install the bo oster retaining nuts and tighten to 16 ft. lbs. (22 Nm) 1994 utility models, 24 ft. lbs. (32 Nm) on 1994 pick-up models and 27 ft. lbs. (36 Nm) on all 1995-97 models.
3. Connect the pedal pushrod and install the washer or switch and the retainer.
4. Connect the vacuum hose.

Fig. Fig. 2: Checking the piston booster rod using the gauge tool

1. For all vehicles cover ed in this guide, gauge the booster rod:
   1. Apply 25 in. Hg (85 kPa) of vacuum using a hand held vacuum pump or apply maximum engine vacuum.
   2. Chec k the maximum and minimum rod lengths using J-37839 or an equivalent pushrod height gauge.
   3. If the piston is not within limits, install a service adjustable piston rod and adjust it to the correct length.
2. Reposition the master cylinder and combination valve bracket to the booster studs, then secure using the retaining nuts. For details, please refer to the master cylinder procedure located earlier in this section.
3. Start and run the engine, then check for proper booster operation.

It is a generic Nissan brake light switch replacement procedure... the brake light switch on a Nissan Altima i.e. controls the illumination of the brake lights. Without the switch, the lights would not go on. The switch has no service life, so when it goes, it usually happens suddenly. New brake light switches can be obtained from Nissan or from a Nissan dealership.

1. Remove the cotter pin from the pin bolt that holds the brake pedal to the brake booster with a pair of pliers. There is a small cotter pin running through the brake pedal to brake booster connection. You need to pull this cotter pin out to remove the larger pin that holds the brake pedal to the brake booster.
2. Slide the pin out of the brake booster mounting bracket.
3. Pull up on the brake pedal to slide it out of the brake booster mounting bracket.
4. Remove the bolts holding the brake switch to the firewall using a socket wrench.
5. Remove the electrical connector on the brake switch by pulling it straight off the switch.
6. Slide the switch off the firewall.
7. Install the new switch. Installation is the reverse of removal. Make sure that you replace the cotter pin in the brake booster to brake pedal connection. The cotter pin prevents the retaining pin in the brake booster mounting bracket from coming off.

Hope helps (remember to rate this answer).

try checking brake fluid what type of car is it year model engine size

In relation to the brake booster, try looking at the vacuum hose that runs from the inlet manifold to the brake booster. It could have become hard and brittle and split causing a bad air/vacuum leak.
Sometimes in older vehicles the rubber diaphragm inside the brake booster can perish and split allowing excessive air through the booster into the inlet manifold

Your brake booster is the heart of your power brakes. It runs off a vacuum from the intake to booster. Your brakes will still work as long as they have fluid. They'll just get stiff. It probably means you need a new one

i think if there is a problem it would be if one had A.B.S. and the other did not, otherwise i can't see any problem. just have to look at it and see if everything lines up. i believe the boosters are the same, if they look the same and bolt up the same i don't see any problem. you might want to chk. with a ford dealer just to see if there is a differance in volume on booster.