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Dave Nova
Dave Nova, Chevrolet Technician
Category: Chevy
Satisfied Customers: 19452
Experience:  ASE Master Certification. GM World Class Certification
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1993 chevy truck: 4x4. the red brake light keeps flashing, 5 times

Resolved Question:

1993 chevy truck, 4x4. the red brake light keeps flashing, 5 times, pause then 5 times... and keeps doing this nonstop. why?
Submitted: 8 years ago.
Category: Chevy
Expert:  Dave Nova replied 8 years ago.

The ABS system is flashing a trouble code 5, follow the diagnostic steps below.



Four Wheel Drive Antilock Brake System Schematic

Diagnostic Trouble Code (DTC) 5, Excessive Dump Valve Actuations During An Antilock Stop

A Diagnostic Trouble Code (DTC) 5 relates to a condition where the Electronic Brake Control Module (EBCM) is having to cycle the dump valve too many times during an anti lock stop. A mechanical locking condition in the rear brakes or powertrain can cause this Diagnostic Trouble Code (DTC) to set. This DTC can also be set if the Rear Wheel Antil Lock (RWAL) system is working with the vehicle in 4WD.

Check if the rear brakes or powertrain are causing the malfunction. This test only applies to vehicles with 4WD.

- Check if the front axle switch can turn on the 4WD indicator on the instrument cluster.
- Check if the voltage is present in CKT 420.
- Check the operation of the front axle switch.
- Check for the 4WD voltage signal at the EBCM.


CAUTION: Do not pierce the electrical connectors, wires, seals, or insulation during testing. Doing so will break the seal and lead to corrosion and failure of the wiring and terminals.

Customer: replied 8 years ago.
i thought to get a code out, that a jump wire was to be used on the connector under the dash, the brake light id flashing the moment you turn the key on
Expert:  Dave Nova replied 8 years ago.
You do normally have to install a jumper wire to put the ABS module into diagnostic mode. Your ABS module may be shorted internally, always thinking it is in diagnostic mode. If this is the case , the module would need to be replaced before proceeding.
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