For 1990-2009 cars
ABS Components
Antilock Brake System Schematics
Handling ESD Sensitive Parts Notice

### Circuit Description

The Electronic Brake Control Module (EBCM) controls the operation of the amber ABS indicator lamp by means of a lamp driver relay.

The amber ABS indicator lamp is connected to the IG COIL fuse. This circuit is hot in ON and START ignition switch positions.

When the lamp driver relay is in the OFF state, the lamp driver relay grounds the amber ABS indicator lamp. This causes the amber ABS indicator lamp to turn ON.

When the EBCM commands OFF the ABS indicator, the EBCM turns ON the lamp driver relay by grounding the ABS indicator control circuit. This causes the lamp driver relay to open the path to ground, turning OFF the amber ABS indicator lamp.

When the ignition switch is turned to the ON position, the EBCM turns ON the ABS indicator for 3 seconds for a bulb check. Whenever a malfunction is detected within the ABS system, the EBCM tuns ON the ABS indicator, notifying the driver that ABS needs to be serviced. If the EBCM commands the red BRAKE warning indicator ON due to an ABS malfunction that may degrade base braking operation and cannot do so, the ABS indicator will flash to indicate the serious nature of the problem.

### Diagnostic Aids

The following conditions may cause a malfunction:

• | A poor connection

• | Rubbed-through wire insulation

• | A broken wire inside the insulation

• | Open IG COIL fuse

• | Open bulb filament

• | Open or poor G201

• | Short to ground in lamp driver relay control circuit

• | Open within I/P gage printed circuit

• | Faulty lamp driver relay (open contacts)

Use the Lamp Test function of the Scan Tool in order to turn the indicator on while looking for an intermittent malfunction in the ABS warning indicator circuitry.

Thoroughly inspect any circuitry that may cause the intermittent complaint for the following conditions:

• | Backed out terminals

• | Improper mating

• | Broken locks

• | Improperly formed or damaged terminals

• | Poor terminal-to-wiring connections

• | Physical damage to the wiring harness

Step | Action | Value(s) | Yes | No
--- | --- | --- | --- | ---
Important: Zero the J 39200 test leads before making any resistance measurements. Refer to the J 39200 user's manual.
1 | Was the ABS Diagnostic System Check performed? | -- | Go to Step 2 | Go to Diagnostic System Check - ABS
2 |

1. Turn the ignition switch to the OFF position.
2. Install a Scan Tool .
3. Turn the ignition switch to the ON position.
4. Select Special Functions on the Scan Tool .
5. Select Lamp Test on the Scan Tool .
6. Use the Scan Tool in order to turn the amber ABS warning indicator ON.

Did the amber ABS warning indicator turn ON?

--

Go to Step 23

Go to Step 3

3 | Remove and inspect the DEF fuse. Is the DEF fuse open? | -- | Go to Step 4 | Go to Step 5
4 | Inspect the YEL/GRN wire between the Junction Block and the Lamp Driver Relay for damage that may cause a short to ground. Is there any damage present? | -- | Go to Step 13 | Go to Step 14
5 |

1. Turn the ignition switch to the ON position.
2. Use the J 39200 in order to measure the voltage between the DEF fuse terminal and ground.

Is the resistance within the specified range?

Battery Voltage

Go to Step 6

Go to Power Distribution Schematics in Wiring Systems

6 |

1. Turn the Ignition switch to the OFF position.
2. Reinstall the DEF fuse.
3. Disconnect the EBCM connector C1.
4. Turn the Ignition switch to the ON position.
5. Connect a fused jumper wire between the EBCM connector C1 terminal B11 and ground.

Did the ABS Warning Indicator turn ON?

--

Go to Step 7

Go to Step 8

7 | Inspect the EBCM connector for the following conditions:

• | Damage

• | Poor terminal contact

• | Terminal corrosion

Is there evidence of damage, poor terminal contact or terminal corrosion?

--

Go to Step 15

Go to Step 16

8 |

1. Disconnect the Lamp Driver Relay connector.
2. Turn the ignition switch to the ON position.
3. Use the J 39200 in order to measure the voltage between the Lamp Driver Relay connector terminal 1 and ground.

Is the voltage within the specified range?

Battery Voltage

Go to Step 9

Go to Step 17

9 | Use the J 39200 in order to measure the resistance between the Lamp Driver Relay connector terminal 3 and the EBCM connector C1 terminal B11. Is the resistance within the specified range? | 0-2 ohms | Go to Step 10 | Go to Step 18
10 | Use the J 39200 in order to measure the resistance between the Lamp Driver Relay connector terminal 4 and ground. Is the resistance within the specified range? | 0-2 ohms | Go to Step 11 | Go to Step 19
11 |

1. Disconnect the Instrument Panel Cluster (IPC) connector C1.
2. Use the J 39200 in order to measure the resistance between the Lamp Driver Relay connector terminal 2 and the IPC connector C1 terminal 7.

Is the resistance within the specified range?

0-2 ohms

Go to Step 12

Go to Step 20

12 | Remove and inspect the ABS Warning Indicator bulb. Refer to Instrument Cluster Bulb Replacement in Instrument Panel, Gauges and Console. Is the ABS Warning Indicator bulb open? | -- | Go to Step 21 | Go to Step 22
13 |

1. Repair the short to ground in the YEL/GRN wire between the Junction Block and the Lamp Driver Relay. Refer to Wiring Repairs in Wiring Systems.
2. Replace the DEF fuse.

Is the repair complete?

--

Go to Diagnostic System Check - ABS

--

14 | Replace the DEF fuse. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
15 | Replace all of the terminals that exhibit signs of damage, poor terminal contact or terminal corrosion. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
16 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
17 | Repair the open or high resistance in the YEL/GRN wire between the Junction Block and the Lamp Driver Relay. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
18 | Repair the open or high resistance in the BLU wire between the Lamp Driver Relay and the EBCM. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
19 | Repair the open or high resistance in the BLK wire between the Lamp Driver Relay and G201. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
20 | Repair the open or high resistance in the BLU/GRN wire between the Lamp Driver Relay and the IPC. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
21 | Replace the ABS Warning Indicator bulb. Refer to Instrument Cluster Bulb Replacement in Instrument Panel, Gauges and Console. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
22 | Replace the Lamp Driver Relay. Refer to Lamp Driver Relay Replacement . Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
23 | The malfunction is not present at this time. Refer to Diagnostic Aids for more information. Is the action complete? | -- | System OK | --