For 1990-2009 cars

### 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? | -- | Go to Step 2 | Go to Brake Warning System Description and Operation
2 | Verify a fault is present. Does the system operate normally? | -- | Go to Testing for Intermittent Conditions and Poor Connections in Wiring Systems | Go to Step 3
3 | Does the low air indicator and the brake warning alarm come on? | -- | Go to Low Air Indicator Always On | Go to Step 4
4 |

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 5

Go to Air Brake System Testing

5 | 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 7 | Go to Step 6
6 | Replace the multifunction alarm module. Refer to Multifunction Alarm Module Replacement in Instrument Panel, Gages, and Console. Did you complete the replacement? | -- | Go to Step 7 | --
7 | Operate the system in order to verify the repair. Did you correct the condition? | -- | System OK | Go to Step 2