Circuit Description
Serial data is transmitted/received by the electronic brake control module (EBCM) through terminal 7. The EBCM is supplied with constant battery feed voltage through terminals 9 and 25, and switched ignition voltage through terminal 4. The EBCM ground is provided through terminal 8 and 24.
Diagnostic Aids
Typical causes of no communication with the EBCM:
| • | Poor terminal contact at the EBCM |
| • | Loss of EBCM ground to terminal 8 and 24 |
| • | Loss of battery voltage at EBCM terminals 9 and/or 25 |
| • | Loss of ignition voltage at EBCM 4 |
| • | Open/grounded data line |
| • | Data line with high resistance |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Did you perform a Diagnostic System Check? | -- | Go to Step 2 | |
2 |
Was the voltage measured within the specified value? | B+ | Go to Step 4 | Go to Step 3 |
3 | Repair the source of the low voltage to terminal 9. Inspect for an open fuse, poor terminal contact, or a grounded wire. Did you find and correct the condition? | -- | System OK | -- |
4 | Connect a voltmeter to the EBCM harness terminal 25 and then to the body ground. Was the voltage measured within the specified value? | B+ | Go to Step 6 | Go to Step 5 |
5 | Repair the source of the low voltage to terminal 25. Inspect for an open fuse, poor terminal contact, or a grounded wire. Did you find and correct the condition? | -- | System OK | -- |
6 |
Was the voltage measured within the specified value? | B+ | Go to Step 8 | Go to Step 7 |
7 | Repair the source of the low voltage to terminal 4. Inspect for an open fuse, poor terminal contact, or a grounded wire. Did you find and correct the condition? | -- | System OK | -- |
8 |
Was the resistance measured less than the specified value? | 2 ohms | Go to Step 10 | Go to Step 9 |
9 | Repair the source of the high resistance between terminal 8 and 24 and body ground. Find and check the ground location where the circuit is secured to body ground. Did you find and correct the condition? | -- | System OK | -- |
10 |
Was the resistance measured less than the specified value? | 2 ohms | Go to Step 12 | Go to Step 11 |
11 | Repair the high resistance between EBCM terminal 21 and DLC terminal 7. Is the repair complete? | -- | System OK | -- |
12 |
Was the resistance measured equal to the specified value? | OL (open circuit) | Go to Step 14 | Go to Step 13 |
13 | Find and repair the short to ground on the data line. Did you find and correct the condition? | -- | System OK | -- |
14 | Replace the EBCM. Refer to Brake Pressure Modulator Valve Assembly Replacement . Did you complete the replacement? | -- | System OK | -- |
