Symptom Diagnosis; Chart A-1 Abs Works Frequently But Vehicle Does Not Decelerate - Isuzu 2000 Trooper Workshop Manual

Symptom Diagnosis

The symptoms that cannot be indicated by the warning
light can be divided in the following five categories:
1. ABS works frequently but vehicle does not
decelerate.
2. Uneven braking occurs while ABS works.
3. The wheels lock during braking.
No. No
1 ABS works frequently but vehicle does not decelerate.
2 Uneven braking occurs while ABS works.
3 The wheels are locked.
4 Brake pedal feel is abnormal.
5 Braking sound (from EHCU) is heard while not braking.
Chart A–1 ABS Works Frequently But Vehicle Does Not Decelerate
Step
1 1. Turn key off.
2. G Sensor connector and EHCU connector disconnected.
Is there continuity between EHCU terminals 26 and 8?
2 Connect EHCU connector.
Is there continuity between the G sensor and the EHCU?
3 Is the G sensor normal? (Refer to chart B-5)
4 Is braking force distribution normal between the front and rear of
the vehicle?
5 Are axle parts installed normally?
6 Is there play in each wheel speed sensor?
7 Is there damage, or powered iron sticking to each wheel speed
sensor/sensor ring?
8 Is the output of each wheel speed sensor normal? (Refer to chart
C-1 or TC-1)
9 Is the input of transmission normal? (Refer to chart C-2 or TC-2)
These are all attributable to problems which cannot be de-
tected by EHCU self-diagnosis. Use the customer com-
plaint and a test to determine which symptom is present.
Then follow the appropriate flow chart listed below.
Sym tom Symptom
Action
BRAKE CONTROL SYSTEM
4. Brake pedal feel is abnormal.
5. Braking sound (from EHCU) is heard while not
braking.
Diagnostic Flow Charts
Without TECH 2
Chart A–1
Chart A–2
Chart A–3
Chart A–4
Chart A–5
Yes
Go to Step 2
Go to Step 3
Go to Step 4
Go to Step 5
Go to Step 6
Repair wheel
speed sensor.
Go to Step 11
Replace sensor
or sensor ring.
Go to Step 11
Go to Step 9
Go to Step 10
5A–19
With TECH 2
Chart TA–1
—
Chart TA–3
—
Chart TA–5
No
Go to Step 3
Repair circuit.
Go to Step 1
Replace G
sensor.
Go to Step 11
Repair brake
parts.
Go to Step 11
Repair axle parts.
Go to Step 11
Go to Step 7
Go to Step 8
Replace wheel
speed sensor or
repair harness.
Go to Step 11
Replace switch or
repair harness.
Go to Step 11