Cutlass Ciera FWD L4-151 2.5L (1982)
Vacuum Pump: Symptom Related Diagnostic Procedures
Excess Brake Effort & Warning Light on
Fig. 11 Vacuum Pump Test Specification Chart
1.
Block wheels, apply parking brake and shift transmission to Park or Neutral position.
2.
Connect suitable vacuum gauge to vacuum pump inlet.
3.
On models equipped with gasoline engine, disconnect outlet hose from vacuum pump and plug the hose.
4.
On all models, run engine at idle and observe vacuum gauge. Vacuum level should reach specified level, Fig. 11, within 30 seconds of starting
engine.
5.
If vacuum meets specifications, check system (other than vacuum pump) for vacuum leaks and repair as necessary.
6.
If vacuum is low, or gauge reading fluctuates, inspect gauge and connections for leaks, then check belt and pulley and idle speed and make any
necessary adjustments or repairs.
7.
If vacuum is still low, replace vacuum pump and recheck. If vacuum now meets specifications, proceed to step 8.
8.
On models equipped with gasoline engine, remove plug from outlet hose and reconnect hose to vacuum pump.
9.
On all models, reconnect vacuum inlet hose with a vacuum gauge teed into the line near the pump.
10.
Run engine at idle and observe vacuum gauge. After one minute, vacuum should not drop more than 3 inches Hg from reading in step 4.
11.
If vacuum does not drop more than 3 inches Hg, the system is functioning properly.
12.
If vacuum does drop more than 3 inches Hg, check all attaching hoses for leaks and repair as necessary. If vacuum is still low, check all vacuum
accessories for leaks and repair or replace as necessary.
Excessive Brake Pedal Effort/VAC. Pump Inop. & Warning Light on
1.
With ignition On, disconnect electrical connector from vacuum pump and check for battery voltage at terminals A and B and for proper ground at
terminal D. If battery voltage is indicated, proceed to step 2. If not, check fusible link, fuse and wiring circuits and repair as necessary.
2.
Connect 12 volt power source to terminals A and B and ground terminal D. If pump is still inoperative, proceed to step 3. If pump now operates,
refer to ``Excessive Brake Pedal Effort, Vacuum Pump Operative & Brake Warning Light On'' diagnosis.
3.
Remove vacuum pump and check for sticking or shorted brushes. Check controller for damaged wires and repair as necessary. If no defects are
found, replace controller. Do not obstruct the outlet nozzle of the vacuum pump during testing. The pump diaphragm can be permanently
damaged.
Excessive Brake Pedal Effort, VAC. Pump OP. & Warning Light on
Fig. 4 Vacuum pump test connection
