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Troubleshooting Diagnostic Trouble Codes: Miscellaneous
1st. Blink
Code Location
12Miscellaneous
2nd. Diagnostic
Blink Trouble Code Code Description
1Stop Lamp Switch Not Detected
Repair Information
ECU has not detected the presence of the stop lamp switch since ignition power was applied (note that stop lamp switch input may be applied to the
2Stop Lamp Switch Defective
Apply and release service brake. Check for brake switch input into ECU (see system wiring schematic). With service brake released, check for presence of the stop lamp bulb. With service brake applied, verify system voltage is now present at the stop lamp switch input to the ECU. Check for damaged wiring between ECU, stop lamp switch and bulb. Check for corroded or damaged connectors. Check for damaged or reversed J1939 wiring. Check for corroded or damaged connectors on J1939 link. Verify presence of engine ECU on the J1939 link. Verify ECU configuration.
3Dynamometer Test Mode
4Retarder Relay Open Circuit or Shorted to Ground
5Retarder Relay Circuit Shorted to Voltage
6ABS Indicator Lamp Circuit Fault
7PMV Common Shorted to Ground
8PMV Common Shorted to Voltage
9ATC Disabled to Prevent Brake Fade
10Tire Size Out of Range (Front to Rear)
11Wheel Speed Sensors Reversed on an Axle
ECU has been placed in the Dynamometer Test Mode by either the diagnostic blink code switch or a
Verify vehicle contains a retarder relay. Verify ECU configuration. Check wiring between ECU and retarder relay. Verify no continuity between retarder disable output of
Check wiring between ECU and retarder relay. Verify no continuity between retarder disable output of
Check operation of diagnostic blink code switch. Check wiring of diagnostic blink code switch, ABS WL, and ABS WL relay (frame ECUs only). Verify ABS WL ground input (cab ECUs only).
Verify no continuity between the CMN of all PMVs, TCV, and Diff Lock Solenoid and ground. Check for corroded/damaged wiring or connectors between the ECU and CMN of all PMVs, TCV, and Diff Lock Solenoid.
Verify no continuity between the CMN of all PMVs, TCV, and Diff Lock Solenoid and voltage. Check for corroded/damaged wiring or connectors between the ECU and CMN of all PMVs, TCV, and Diff Lock Solenoid.
ATC is temporarily disabled to prevent excessive heating of the foundation brakes.
Verify correct tire size as desired. Verify proper tire inflation. Verify correct number of exciter ring teeth. Verify that the ECU has the proper tire size settings.
Sensors are reversed (left to right) on one of the axles. Verify proper installation, connection, and wiring of the sensors.
12 | Diff. Lock Solenoid Shorted | Verify no continuity between the Diff Lock Solenoid and ground. Check for corroded/ |
| to Ground or Open Circuit | damaged wiring or connectors between the ECU and Diff Lock Solenoid. |
13 | Diff. Lock Solenoid | Verify no continuity between the Diff Lock Solenoid and voltage. Check for corroded/ |
| Shorted to Voltage | damaged wiring or connectors between the ECU and Diff Lock Solenoid. |
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