GM Service Manual Online
For 1990-2009 cars only

Circuit Description

The Low Air Indicator illuminates when ground is applied to the Low Air Indicator Control Circuit.

Step

Action

Values

Yes

No

Schematic Reference: Brake Warning System Schematics

1

Did you review the Brake Warning System Description and Operation and perform the necessary inspections?

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Go to Step 2

Go to Symptoms - Air Brakes

2

Verify a fault is present.

Does the system operate normally?

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Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems

Go to Step 3

3

  1. Start the vehicle.
  2. Inspect the air pressure gage.

Does the air pressure gage indicate the air pressure is above the specified value?

480 kPa (70 psi)

Go to Step 4

Go to Air Brake System Testing

4

  1. Turn OFF the ignition.
  2. Disconnect one of the low air pressure switches.
  3. Turn ON the ignition.

Does the low air indicator turn OFF?

--

Go to Step 7

Go to Step 5

5

  1. Turn OFF the ignition.
  2. Disconnect the other low air pressure switch.
  3. Turn ON the Ignition.

Does the low air indicator turn OFF?

--

Go to Step 7

Go to Step 6

6

Inspect the low air indicator control circuit for a short to ground. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?

--

Go to Step 9

Go to Step 8

7

Replace the low air pressure switch. Refer to Low Air Pressure Switch Replacement .

Did you complete the replacement?

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Go to Step 9

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8

Replace the instrument panel cluster. Refer to Instrument Cluster Replacement in Instrument, Panel, Gages and Console.

Is the replacement complete?

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Go to Step 9

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9

Operate the system in order to verify the repair.

Did you correct the condition?

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System OK

Go to Step 2