Circuit Description
DTC C1278 identifies a brake solenoid valve that cannot be energized. The malfunction may be caused by one of the following conditions:
| • | An open in the solenoid valve circuitry |
| • | The solenoid valve is always energized due to a short to ground in the solenoid valve circuitry between the driver and the brake solenoid valve. |
An open will not allow proper ABS operation, but the short to ground simply turns ON the brake solenoid valve. A path for base brakes is still allowed once the motor rehomes and the check ball is lifted off its seat during key to RUN initialization.
Conditions for Setting the DTC
DTC C1278 can set only when the solenoid is commanded off while the Electronic Brake Control Relay is enabled.
A malfunction exists if the EBCM detects the right front brake solenoid valve control circuit voltage is not within specifications.
Action Taken When the DTC Sets
| • | A malfunction DTC stores. |
| • | The ABS disables. |
| • | The ABS warning indicator turns ON. |
Conditions for Clearing the DTC
| • | The condition responsible for setting the DTC no longer exists and the Scan Tool Clear DTCs function is used. |
| • | 100 drive cycles pass with no DTCs detected. A drive cycle consists of starting the vehicle, driving the vehicle over 16 km/h (10 mph), stopping and then turning the ignition off. |
Diagnostic Aids
The following conditions may cause an intermittent malfunction:
| • | A poor connection |
| • | Rubbed-through wire insulation |
| • | A broken wire inside the insulation |
Use the enhanced diagnostic function of the Scan Tool in order to measure the frequency of the malfunction.
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
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This test checks for a short to ground in the right front solenoid valve circuit.
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This test checks for an open in the underhood junction block.
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This test checks for an open in the battery feed circuit of the solenoid.
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This test checks for an open in the right front solenoid valve.
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This test checks for an open in the control circuit of the solenoid.
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This test determines if the malfunction is caused by the EBCM.
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This test checks for a short to ground in the right front solenoid valve.
Step | Action | Value(s) | Yes | No | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
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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 | |||||||||||||
2 | Remove and inspect the ABS SOL Fuse (15 A). Is the fuse open? | -- | Go to Step 11 | Go to Step 3 | ||||||||||||
Is the resistance within the specified range? | OL (Infinite) | Go to Step 4 | Go to Step 10 | |||||||||||||
Use the J 39200 with the J 35616 in order to measure the resistance between the Electronic Brake Control Relay harness connector terminal 87 and the ABS SOL Fuse (15 A) terminal. Is the resistance within the specified range? | 0-2 ohms | Go to Step 5 | Go to Step 14 | |||||||||||||
Is the resistance within the specified range? | 0-2 ohms | Go to Step 6 | Go to Step 15 | |||||||||||||
Use the J 39200 in order to measure the resistance between the right front ABS brake solenoid valve terminal A and the right front brake solenoid valve terminal B. Is the resistance within the specified range? | 2-5 ohms | Go to Step 7 | Go to Step 16 | |||||||||||||
Use the J 39200 in order to measure the resistance between the EBCM harness connector terminal 19 and the right front brake solenoid valve harness connector terminal B. Is the resistance within the specified range? | 0-2 ohms | Go to Step 8 | Go to Step 17 | |||||||||||||
8 |
Are terminal corrosion, damaged terminals, or poor terminal contact evident? | -- | Go to Step 18 | Go to Step 9 | ||||||||||||
Do not start the engine. Does DTC C1278 set as a current DTC? | -- | Go to Step 19 | Go to Step 20 | |||||||||||||
Is the resistance within the specified range? | OL (Infinite) | Go to Step 17 | Go to Step 16 | |||||||||||||
11 | Inspect CKT 855 for damage that may cause a short to ground. Is there damage that may cause a short to ground? | -- | Go to Step 12 | Go to Step 13 | ||||||||||||
12 | Repair damage to CKT 855 and replace the ABS SOL Fuse (15 A). Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||||||
13 | Replace the ABS SOL Fuse (15 A). Is the repair complete? | -- | -- | |||||||||||||
14 | Replace the Underhood Junction Block. Refer to Underhood Fuse Block Replacement in Engine Electrical. Is the repair complete? | -- | -- | |||||||||||||
15 | Repair the open or high resistance in CKT 855. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||||||
16 | Replace the right front brake solenoid valve. Refer to Brake Solenoid Valve Replacement . Is the repair complete? | -- | -- | |||||||||||||
17 | Repair the short to ground in CKT 827. Refer to Wiring Repairs in Wiring Systems. Is the repair complete? | -- | -- | |||||||||||||
18 | Replace all the terminals and connectors that exhibit the following conditions:
Is the repair complete? | -- | -- | |||||||||||||
19 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Is the repair complete? | -- | -- | |||||||||||||
20 | Malfunction is intermittent or is not present at this time. Refer to Diagnostic Aids for more information. Is the action complete? | -- | System OK | -- | ||||||||||||
