For 1990-2009 cars

### Circuit Description

The electronic brake control module (EBCM) controls the operation of the amber ABS warning lamp by means of a lamp driver module contained within the cluster.

Battery voltage is supplied to the clock terminal 17, and the electronic brake control module terminal 4 when the ignition switch is turned ON. EBCM terminals 9 and 25 are hot at all times.

The default state is for the lamp driver module to turn ON the amber ABS warning lamp, by supplying a ground path through the lamp driver module.

When the EBCM commands the ABS lamp OFF, the EBCM will ground the ABS warning lamp control circuit. This causes the lamp driver module to open the path to ground for the bulb.

When the ignition switch is turned to the ON position, the EBCM turns ON the ABS warning lamp for 3 seconds for a bulb check.

Whenever a malfunction is detected within the ABS system, the EBCM turn ON the ABS warning lamp, notifying the driver that the ABS needs to be serviced.

### Diagnostic Aids

Typical causes of the ABS warning lamp inoperative with no DTCs set.

• | Faulty ABS bulb/loose socket

• | I/P fuse open

• | Faulty cluster/lamp driver module

• | Faulty EBCM

• | Grounded circuit between the EBCM and the cluster

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
1 | Did you perform the Diagnostic System Check -- Vehicle? | -- | Go to Step 2 | Go to Diagnostic System Check - Vehicle
2 |

1. Disconnect the electronic brake control module (EBCM).
2. Turn ON the ignition, with the engine OFF.

Did the amber ABS lamp turn ON?

--

Go to Step 3

Go to Step 4

3 | Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you completer the replacement? | -- | System OK | --
4 | Check the cluster fuse. Is the fuse and terminal contact OK? | -- | Go to Step 6 | Go to Step 5
5 |

1. Replace the open fuse and/or repair the loose terminals.
2. Find the short, which caused the fuse to open, if applicable.

Did you find and correct the condition?

--

System OK

--

6 |

1. Remove the amber ABS bulb from the clock.
2. Inspect for an open bulb filament or poor socket contact.

Was the socket and the bulb OK?

--

Go to Step 8

Go to Step 7

7 | Replace the bulb/socket as needed. Did you complete the replacement? | -- | System OK | --
8 |

1. Turn the Ignition switch OFF.
2. The EBCM harness is still disconnected.
3. Remove the clock assembly from the instrument panel.
4. Disconnect the harness connector from the clock assembly.
5. Turn ON the ignition, with the engine OFF.
6. Connect a voltmeter to terminal 17 of the clock harness and then to body ground.

Was the voltage within the specified value?

B+

Go to Step 10

Go to Step 9

9 | Find and repair the source of low voltage on the clock voltage supply terminal. Did you find and correct the condition? | -- | System OK | --
10 |

1. Turn the Ignition switch OFF.
2. Disconnect the clock harness connector.
3. Connect an ohmmeter between the clock harness terminal 4 and lamp driver module (LDM) harness terminal F.

Was the resistance measured less than the specified value?

2 ohms

Go to Step 12

Go to Step 11

11 | Repair the open or high resistance between the cluster and the LDM. Did you find and correct the condition? | -- | System OK | --
12 |

1. Turn the Ignition switch OFF.
2. The LDM harness and the EBCM harness are still disconnected.
3. Connect an ohmmeter to the EBCM harness terminal 16 and then to body ground.

Is the resistance as specified?

OL (open circuit)

Go to Step 14

Go to Step 13

13 | Find the repair to the short to ground between the cluster harness and the EBCM harness. Did you find and correct the condition? | -- | System OK | --
14 | Replace the LDM. Did you complete the replacement? | -- | System OK | Go to Step 15
15 | Replace the cluster assembly. Refer to Instrument Cluster Replacement . Did you complete the replacement? | -- | System OK | --