Isuzu Trooper (2000 year). Manual - part 409

7A1–50 TRANSMISSION CONTROL SYSTEM (4L30–E)

DTC P0723 Automatic Transmission Output Speed Sensor (OSS) Intermittent  (Cont’d)

Step

No

Yes

Action

13

Repair the open in circuit WHT.

Is the repair complete?

Go to Step 17

—

14

Check circuit RED for a short to ground or open.

Was a problem found and corrected?

Go to Step 17

Go to Step 16

15

Repair the short to B+ in circuit RED.

Is the repair complete?

Go to Step 17

—

16

Replace the PCM. Refer to Powertrain Control Module (PCM) in
Automatic Transmission (4L30–E) section.

Is the replacement complete?

Go to Step 17

—

17

1. After the repair is complete, use the scan tool to select “DTC”,

then “Clear Info” function and operate the vehicle under the
following conditions:
Transmission output speed is greater than 101 rpm for 3
seconds.

2. Review the scan tool “DTC Info”.

Has the last test failed or is the current DTC displayed?

Begin diagnosis

again

Go to Step 1

Repair verified
Exit DTC table

TRANSMISSION CONTROL SYSTEM (4L30–E)

7A1–51

DTC P0724 Brake Switch Circuit High (Stuck Off)

D07RY00012

Circuit Description:

The brake switch indicates brake pedal status to the
Powertrain Control Module (PCM). The brake switch is a
normally–closed switch that supplies battery voltage on
circuit ORN to the PCM. Applying the brake pedal opens
the switch, interrupting voltage to the PCM. When the
brake pedal is released, the PCM receives a constant
voltage signal. If the PCM receives a zero voltage signal
at the brake switch input, and the Torque Converter
Clutch (TCC) is engaged, the PCM de–energizes the
Torque Converter Clutch Solenoid Valve (TCC Sol.
Valve). The PCM disregards the brake switch input for
TCC scheduling if there is a brake switch circuit fault
(Refer to Diagnostic Aids).
When the PCM detects a closed brake switch circuit (12
volts, high input) during decelerations, then DTC P0724
sets. DTC P0724 is a type D DTC.

Conditions For Setting The DTC

D

No OSS Assy. DTCs P0722 or P0723.

D

The PCM detects a closed brake switch circuit (12
volts) without changing and the following events
occur seven consecutive times:

D

The vehicle speed is greater than 32 km/h (20 mph)
for 4 seconds;

D

then the vehicle speed is between 8–32 km/h (5–20
mph) for 4 seconds;

D

then the vehicle speed is less than 8 km/h (5 mph).

Action Taken When The DTC Sets

D

The PCM does not illuminate the Malfunction
Indicator Lamp (MIL).

D

DTC P0724 stores in PCM history.

Conditions For Clearing The DTC

D

A scan tool can clear the DTC from the PCM history.
The PCM clears the DTC from the PCM history if the
vehicle completes 40 warm–up cycles without a
failure reported.

D

The PCM cancels the DTC default actions when the
fault no longer exists and the ignition is OFF long
enough in order to power down the PCM.

Diagnostic Aids

D

Inspect the wiring for poor electrical connection at the
PCM. Look for possible bent, backed out, deformed
or damaged terminals. Check for weak terminal
tension as well. Also check for a chafed wire that
could short to bare metal or other wiring. Inspect for a
broken wire inside the insulation.

D

When diagnosing for a possible intermittent short or
open condition, move the wiring harness while
observing test equipment for a change.

D

Check customer driving habits and/or unusual traffic
conditions (i.e. stop and go, expressway).

D

Check brake switch for proper mounting and
adjustment.

7A1–52 TRANSMISSION CONTROL SYSTEM (4L30–E)

Test Description

The numbers below refer to the step numbers on the
diagnostic chart.
2. This step isolates the brake switch as a source for

setting the DTC.

DTC P0724 Brake Switch Circuit High (Stuck Off) 

Step

Action

Yes

No

1

Was the Powertrain On–Board Diagnostic (OBD) System Check
performed?

Go to Step 2

Go to Powertrain

OBD System

Check

2

1. Install the scan tool.
2. With the engine “off,” turn the ignition switch to the “on”

position.

NOTE: Before clearing the DTC(s), use the scan tool in order to
record the “Failure Records” for reference. Using the “Clear Info”
function will erase the stored “Failure Records” from the PCM. 

3. Record the DTC Failure Records, then clear the DTC(s).
4. Select “TCC Brake Switch” on the scan tool.
5. Disconnect the brake switch connector from the brake switch.

Did the TCC brake switch status change from “Closed” to “Open”?

Go to Step 3

Go to Step 4

3

Replace the brake switch.

Is the replacement complete?

Go to Step 6

—

4

Inspect circuit ORN for a short to B+ condition. Repair the circuit if
necessary.

Did you find a short to B+ condition?

Go to Step 6

Go to Step 5

5

Replace the PCM.

Is the replacement complete?

Go to Step 6

—

6

In order to verify your repair, perform the following procedure:
1. Select DTC.
2. Select “Clear Info”.
3. With the engine “off” turn the ignition switch to the “on” position.
4. Apply the brake pedal.
5. Verify that the TCC brake switch status indicates “Open” (0

volts) for 2 seconds.

6. Select Specific DTC. Enter DTC P0724.

Has the test run and passed?

System OK

Begin the

diagnosis again.

Go to Step 1

TRANSMISSION CONTROL SYSTEM (4L30–E)

7A1–53

DTC P0730 Gear Error Without Input Speed

D07RY00055

Circuit Description

D

The Powertrain Control Module (PCM) calculates the
slippage of the converter and transmission based
upon the engine speed, the output speed, and the
current gear ratio.

D

The slippage of the converter at a high enough engine
speed is low.  The transmission should not slip more
than a given value when there is no shift.

D

This DTC detects a slip at each gear.  This is a type
“C” DTC.

Conditions For Setting The DTC

D

No Output Speed Sensor DTC(s) P0722, P0723.

D

Not in Park, Neutral, or Reverse.

D

Engine speed is greater than 3,500 rpm.

D

3 seconds since upshift.

D

No Transmission Range Switch DTC(s) P0705,
P0706.

D

3 seconds since downshift.

D

3 seconds since garage shift (N

→

D).

D

And one of the following conditions occur:

–  Slip is greater than 508 rpm in 1st gear.

–  Slip is greater than 468 rpm in 2nd gear.

–  Slip is greater than 449 rpm on 3rd gear.

–  Slip is greater than 440 rpm on 4th gear.

D

All conditions met for 5.5 seconds.

Action Taken When The DTC Sets

D

Maximum line pressure.

D

The PCM will not illuminate the Malfunction Indicator
Lamp (MIL).