Malfunction 4WD (ABS) — Toyota Mark II, 2.5 liter, 1997

It started with the fact that I got into a heavy downpour on a clay section of the road, then I realized that the four-wheel drive does not work for me. I read the forums, it turned out that 4WD was connected through ABS, but not one of the bulbs was on, because they were not in the brush!
I pulled out the brushes, put in new bulbs, the garland is on, everything is on)))
According to the description, I did a self-diagnosis, I got a lot of errors on the ABS, reset the errors, I think now there is only one. There is a break on the rear left speed sensor, soldered the wire, reset it, voila, there are no errors. The lamps go out after the ignition is turned on as expected. ABS and 4WD working
Below is info on self-diagnostics of the ABS system

GENERAL INFORMATION

The Automatic Brake Release System (ABS) is designed to improve vehicle stability during heavy braking or when driving in poor road conditions. This is ensured by the fact that the pressure in the brake circuit is regulated depending on the speed of rotation of the wheels recorded by the sensors.

The location of the units of the anti-lock braking system (ABS-system)

1. Actuator
2, 10. Front speed sensors
3. Diagnostic connector (DLC1)
4. Control unit
5. ABS warning lamp
6, 11. Speed ​​sensor rotors
7. Rear speed sensors
8. Diagnostic connector (DLC1)
9. Brake Light Switch
12. ABS Motor Relay
13. Solenoid Valve Traction Relay

ABS units

ACTUATOR

The actuator consists of a master cylinder, an electro-hydraulic pump and 4 solenoid valves.
The prevention
ABS systems are delivered by Bosch and Nippondenso firms. The Bosch system actuator has a monobloc design and contains an integrated processor control unit and a solenoid valve relay, while in the Nippondenso system these components are mounted separately.

The electric pump is designed to pump fluid into the actuator receivers, through which fluid is supplied under pressure to the brake circuit.
Solenoid valves control the pressure in the brake circuit when the ABS system is activated, the valve block contains 4 valves, 1 valve per wheel.

WHEEL SPEED SENSORS

Rotary type sensors mounted on each of the wheels. The signals from the sensors are sent to the control unit.

The front sensors are mounted on the steering knuckle, next to the toothed rings of the rotors. The rotors are structurally integrated with the front outer CV joints of the axle shafts.

The rear sensors are mounted on the rear axle brackets, the rotors are structurally integrated with the rear hub.

ABS CONTROL UNIT

The Nippondenso system control unit is mounted under the front bulkhead, the Bosch system control unit is mounted in the actuator. The unit receives signals from the brake light switch and speed sensors for each wheel. These signals are the initial data for adjusting the pressure in the hydraulic drive of this wheel. The control unit also has the function of self-diagnosis and failure storage.

If the system fails, the control lamp on the instrument panel lights up, and a failure code is stored in the memory, which can be read and determine the nature of the malfunction or a faulty unit.

Diagnostic codes

The fault code is stored in memory until the contents of the memory cells are erased, or until the fault is eliminated.

When the ignition is switched on, the ABS warning lamp lights up, and goes out after the engine is started. If the lamp continues to burn, then a malfunction has been registered in the ABS system.

To access the fault codes, turn the ignition key to the OFF position (engine not running). In the Nippondenso system, remove the jumper (see photo) of the diagnostic connector pins. On both types of systems, bridge the terminals E1 and Tc of the connector, turn the ignition key to the ON position (the engine is not running) and read the codes.

Nippondenso ABS Diagnostic Connector Jumper

1. Jumper

Jumper pins on two types of used diagnostic connectors

The numbers of the two-digit code are determined by the number of flashes of the control lamp, separated by a pause of 1.5 seconds (for example, code 34 - 3 flashes, a pause of 1.5 seconds and 4 flashes).
The next code (if there is another malfunction) appears 2.5 seconds after the first one. If the system is working, the lamp flashes with a period of 0.5 s.

Determine the nature of the failure according to the attached table.

After reading, erase the codes, to do this, bridge the terminals E1 and Tc of the connector, turn the ignition key to the ON position (the engine is not running) and press the pedal at least 8 times within 5 seconds. Remove the jumper and replace the connector cover. Take the car to a car service.

Table of ABS system failure codes

CODE
FAULT
NATURE ACTION TO BE TAKEN
11
Open circuit in solenoid relay circuit Check solenoid valve relay and relay circuit wiring
12
Short circuit in solenoid valve relay circuit Ditto
13
Open circuit in pump motor relay relay circuit Check pump relay circuit and relay circuit wiring
14
Short circuit in pump motor relay circuit Ditto
21
Right front wheel solenoid circuit faulty Check actuator solenoid and circuit
22
Left front wheel solenoid circuit faulty Ditto
23
Right rear wheel solenoid circuit faulty Ditto
24
Left rear wheel solenoid circuit faulty Ditto
25
Open or short circuit in SMC1 circuit Check system actuator and circuit
26
Open or short circuit in SMC2 circuit Check system actuator and circuit
27
Open or short circuit in SRC1 circuit Check system actuator and circuit
28
Open or short circuit in SRC2 circuit Check system actuator and circuit
31
Faulty right front wheel speed sensor Check speed sensors, wiring and sensor connector
31
No signal from right front wheel speed sensor Check speed sensor, wiring and sensor connector
32
No signal from left front wheel speed sensor Ditto
33
No signal from the right rear wheel speed sensor The same
34
No signal from the left rear wheel speed sensor The same
35
Open circuit in the right front wheel speed sensor circuit The same
36
Open circuit in the left front wheel speed sensor circuit The same
37
Number of sensor rotor teeth speed does not correspond to normal Check the health of the sensor rotor (presence of all teeth)
38
Open circuit in the right rear wheel speed sensor circuit or in the sensor itself. Check speed sensor, sensor wiring and connector
39
Open circuit in left rear wheel speed sensor circuit or sensor itself Check speed sensor, sensor wiring and connector
41
Too low voltage on the battery Check up system of a charge: generator (subsection 3.4.10 see), battery (subsection 3.4.9 see), voltage regulator (subsection 3.4.11 see).
43
Brake release control failure Check all ABS wires and connectors
44
Open or short in NE signal circuit Check all wires and connectors from ABS control unit
49
Open in brake light switch circuit or switch itself Check switch and circuit switch
51
Actuator motor blocked Check for short circuit in motor and relay circuit, check battery
53
PCM circuit failure Check all wires and connectors from ABS control unit
58
An open in the brake light switch circuit or in the switch itself Check the switch and the switch circuit
61
Engine control system failure Check the engine management system failure codes (see subsection 7.2.)
62
Control unit failure Control unit repair or replacement required
Light is on continuously
Control unit failure Required repair or replacement of the control unit