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

### Circuit Description

Four-way serial communication is sent back and forth between the EBCM, IPC, PCM, and the BCM. A message from the IPC is sent to the BCM within seven seconds after ABS initialization. A serial communication failure does not allow the proper warning indicator commands to be sent back to the IPC.

### Diagnostic Aids

The frequency of the malfunction can be checked by using the ENHANCED DIAGNOSTIC function of the scan tool, as described in Enhanced Diagnostics, found in this section.

The following conditions may cause an intermittent malfunction:

• | A poor connection

• | Rubbed-through wire insulation

• | A broken wire inside the insulation

Use the Lamp Test function of the Scan Tool in order to turn the indicator on while looking for an intermittent malfunction in the ETS OFF 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

### Test Description

1. This test determines if the malfunction is caused by the IPC.

2. This test determines if the malfunction is caused by the ETS Off switch.

3. This test checks for an open or high resistance in the ETS Off switch ground circuit.

4. This test checks for an open or high resistance in the switched input to the BCM.

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 Body menu then IPC on the Scan Tool .
5. Select Lamp Test on the Scan Tool .
6. Use the Scan Tool in order to turn the Warning Indicators ON.

Did the amber ETS OFF warning indicator turn ON?

--

Go to Step 3

Go to Diagnostic System Check - Instrument Cluster in Instrument Panel, Gauges and Console

3 |

1. Disconnect the ETS Off switch connector.
2. Using a fused jumper wire connect the ETS Off switch harness connector terminal A and terminal D (Pontiac) or terminal B (Olds).

Does the ETS Off warning indicator turn ON?

--

Go to Step 7

Go to Step 4

4 | Using the J 39200 measure the resistance between the ETS Off switch harness connector terminal D (Pontiac) or terminal B (Olds) and ground. Is the resistance within the specified range? | 0-2 ohms | Go to Step 5 | Go to Step 8
5 |

1. Disconnect the BCM connector C3
2. Using the J 39200 measure the resistance between the BCM harness connector C3 terminal A5 and the ETS Off switch harness connector terminal A.

Is the resistance within the specified range?

0-2 ohms

Go to Step 6

Go to Step 9

6 | Inspect all of the connectors and the terminals for the following conditions:

• | Poor terminal contact

• | Evidence of corrosion

Is there evidence of poor terminal contact or corrosion?

--

Go to Step 10

Go to Step 11

7 | Replace the ETS Off switch. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
8 | Repair the open or high resistance in CKT 251. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
9 | Repair the open or high resistance in CKT 1571. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
10 | Replace all of the terminals that exhibit signs of poor terminal contact or corrosion. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --
11 | Replace the BCM. Is the repair complete? | -- | Go to Diagnostic System Check - ABS | --