Chevy Forum

[Peter Stahl]

Anyone know of a good Chevy forum? I have a 1998 Chevy Silverado and after getting the brake booster installed the cruise stopped working. First thing I did was check the fuse, it was good but the voltage reading with the key on was only about 3 volts. All the other fuses read >12.5 volts. The Truck is old so I would like to try and trouble shoot it before I accuse the mechanic of messing it up.

[Dick Adair]

My old 1996 T&C van had the same problem after a repair. There was a vacuum line disconnected.

[Peter Stahl]

No vacuum line of this truck, cruise has a electronic module.

[Mike Lassiter]

not for sure about your specific truck, but look under the dash to the area the rod from the booster attaches to the brake petal. "USE TO BE" a couple of switches that the brake pedal would push against with the pedal fully up. Some are a slip fit adjustment, some screw adjust. It is posible the switch for the cruise control. The switch would open and break the circuit when you touch the brake pedal slightly (enough to make brake lights come on. When the brake booster pushrod gets disconnected from the brake pedal the switch(es) if slip adjust type, can be pushed back towards front seat enough to cause this. The switch isn't pushed against the pedal enough to be "on" anymore. Typically the booster pushrod will limit how far the brake pedal can go up (not applied) and when the rod isn't holding the pedal, the switch can be pushed back. Possibly oversight the mechanic forgot to make sure both switches were properly adjusted after reconnecting the booster pushrod to the brake pedal.

[Peter Stahl]

not for sure about your specific truck, but look under the dash to the area the rod from the booster attaches to the brake petal. "USE TO BE" a couple of switches that the brake pedal would push against with the pedal fully up. Some are a slip fit adjustment, some screw adjust. It is posible the switch for the cruise control. The switch would open and break the circuit when you touch the brake pedal slightly (enough to make brake lights come on. When the brake booster pushrod gets disconnected from the brake pedal the switch(es) if slip adjust type, can be pushed back towards front seat enough to cause this. The switch isn't pushed against the pedal enough to be "on" anymore. Typically the booster pushrod will limit how far the brake pedal can go up (not applied) and when the rod isn't holding the pedal, the switch can be pushed back. Possibly oversight the mechanic forgot to make sure both switches were properly adjusted after reconnecting the booster pushrod to the brake pedal.

Thanks for the reply. That sounds like it could cause a problem. Will it make the Voltage at the fuse show low?

[Mike Lassiter]

I don't know. If the switch is tied to ECU it could ground circuit when pedal depressed and ECU would detect that and know to deactivate cruise control. I was trying to describe a "maybe could be, caused by booster replacement.