Test 21A - Left Front Solenoid Circuit

Test 21A: Repairing -- Left Front Solenoid Circuit (Part 1 Of 3):

Test 21A: Repairing -- Left Front Solenoid Circuit (Part 2 Of 3):

Test 21A: Repairing -- Left Front Solenoid Circuit (Part 3 Of 3):

Modulator Circuits:

Hydraulic Control Unit:

Modulator 6-Way Connector (Harness End):

NOTE: You must perform Test 2A, before proceeding with this test.

LF SOLENOID CIRCUIT SHORTED

When Its Monitored
Any time the system relay is energized, system relay output voltage must be above 9 volts and below 20 volts. The solenoid channels are tested every minute when not in Antilock Brake System (ABS) cycling, and every 620ms when in cycling. Each solenoid is tested separately at 5 ms intervals, with a complete test taking 20ms to complete.

Set Condition
The modulator is a group of four solenoid valves controlled by the Controller Antilock Brake (CAB) to modulate brake pressure during ABS control. One solenoid valve controls each wheel. Solenoid power is supplied through the CAB's internal solenoid drivers. The CAB receives power for the solenoids from the system relay located in the relay box. The CAB monitors each driver circuit when it is on and will store a trouble code if the solenoid voltage is below a calculated threshold referenced to the system relay output voltage.

Possible Causes:
^ Decay solenoid control circuit shorted to ground
^ Shorted solenoid coil
^ Failed solenoid driver

LF SOLENOID CIRCUIT OPEN

When Its Monitored
Any time the system relay is energized, system relay output voltage must be above 9 volts and below 20 volts. The static solenoid test is conducted only when not in ABS cycling. It runs once each 630 ms. The dynamic solenoid test is run every minute when not in ABS cycling and every 620 ms when in cycling. Each solenoid is tested separately at 5 ms intervals with a complete test taking 20 ms to complete.

Set Condition
The modulator is a group of four solenoid valves controlled by the CAB to modulate brake pressure during ABS control. One solenoid valve controls each wheel. Solenoid power is supplied through the CAB's internal solenoid drivers. The CAB receives power for the solenoids from the system relay located in the relay box. The CAB monitors each driver circuit when it is off and will store a trouble code if the solenoid voltage is above 2 volts during a static test or above a calculated threshold referenced to the system relay output voltage during a dynamic test.

Possible Causes:
^ Open decay solenoid control circuit
^ Open decay solenoid coil
^ Failed solenoid driver
^ Loose or corroded connector terminals
^ Decay solenoid control circuit shorted to B(+)
^ High resistance in the decay solenoid circuit