DTC C1251 detects a stripped nut or gear assembly during initialization. During the homing sequence, the piston should reach the top of the bore. Then the ABS motor stalls. If the ABS motor does not stall, the ABS motor must be spinning with little or no resistance. This indicates a nut/screw or gear malfunction.
• | DTC C1251 can only set during initialization. |
• | A malfunction exists if the feedback current is less than the command current for a specified period of time. |
• | A malfunction DTC stores. A corresponding DTC C1286 will also set. |
• | The ABS disables. |
• | The ABS warning indicator turns ON. |
• | The red BRAKE warning indicator turns ON. |
• | 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 switch to the OFF position. |
An intermittent malfunction in this DTC may result from a mechanical part of the system that slips, such as a stripped gear or a backed off gear retaining nut.
Depending on the frequency of the malfunction, a physical inspection of the mechanical parts suspected of causing the malfunction may be necessary.
Step | Action | Value(s) | Yes | No | ||||
---|---|---|---|---|---|---|---|---|
Important: Zero J 39200 test leads before making any resistance measurements. Refer to J 39200 user's manual. | ||||||||
1 | Was the Diagnostic System Check performed? | -- | Go to Diagnostic System Check | |||||
2 |
Do not start the engine. Does DTC C1264 also set as a current DTC? | -- | ||||||
3 |
Observe the following currents:
Were the rear ABS motor command current and the rear ABS motor feedback current approximately the specified current? | 10 A | ||||||
4 |
Could the assistant spin the rear wheels? | -- | ||||||
5 |
Could the assistant spin the rear wheels? | -- | ||||||
6 |
Is the resistance within the specified range? | 0-2 ohms | ||||||
7 | Use the J 39200 in order to measure the resistance between the ABS brake motor pack connector terminal D and the EBCM connector terminal E. Is the resistance within the specified range? | 0-2 ohms | ||||||
8 | Use the J 39200 in order to measure the resistance between the ABS brake motor pack connector terminal C and the ABS brake motor pack connector terminal D. Is the resistance within the specified range? | 0.2-1.5 ohms | ||||||
9 |
(The ABS brake motor pack is the unit with the three small gears. The ABS brake motor pack rear gear is the middle gear when the ABS brake modulator is mounted in the vehicle.) Is the ABS brake motor rear gear stripped? | -- | ||||||
10 | Inspect for a stripped ABS brake modulator rear gear. (The ABS brake modulator unit is the unit with the three large gears. The ABS brake modulator rear gear is the middle gear when the ABS brake modulator is mounted in the vehicle.) Is the ABS brake modulator rear gear stripped? | -- | ||||||
11 |
Secure the assembly in a position that permits observation of the gears. Do not start the engine. (The ABS brake modulator rear gear is the middle gear when the ABS brake modulator is mounted in the vehicle.) Does the ABS brake modulator rear gear set move at least one full revolution in both directions? | -- | ||||||
12 |
Does the ABS brake modulator rear gear rotate more than 3.5 full turns from lock to lock? | -- | ||||||
13 |
Do any of the terminals exhibit poor terminal contact or corrosion? | -- | ||||||
14 |
Does DTC C1251 set as a current DTC? | -- | ||||||
15 | Repair the high resistance in CKT 1284. Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||
16 | Repair the high resistance in CKT 1285. Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||
17 | Replace the ABS brake motor pack. Refer to ABS Motor Pack Replacement . Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||
18 | Replace the ABS brake modulator gear. Refer to Brake Pressure Modulator Valve Assembly Replacement . Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||
19 | Replace the ABS brake modulator. Refer to Brake Pressure Modulator Valve Assembly Replacement . Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||
20 | Replace the terminals that exhibit signs of poor terminal contact or corrosion. Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||
21 | Replace the EBCM. Refer to Electronic Brake Control Module Replacement . Is the repair complete? | -- | Go to Diagnostic System Check | -- | ||||
22 | The malfunction is intermittent or not present at this time. Refer to Diagnostic Aids for more information. Is the repair complete? | -- | Go to Diagnostic System Check | -- |