Isuzu Trooper (1998-2002 year). Manual - part 518

6E–442

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) 

P1635 Reference Voltage # 1 Circuit Fault

D06RY00077

Circuit Description

The TP sensor # 1 shares a 5 Volt reference with the
PCM.
If the PCM detects the 5 Volt reference for the TP sensor #
1 is failure, DTCP1635 will be set.

Conditions for setting the DTC

D

The ignition is “ON”.

D

The 5 Volt reference voltage for the TP sensor # 1 is
less than 4 volts.

D

The 5 Volt reference voltage for the TP sensor # 1 is
more than 5 volts.

Action Taken When the DTC Sets

D

The PCM will not illuminate the malfunction indicator
lamp (MIL) .

D

The PCM will store condition which were present when
the DTC was set as Freeze Frame and in the Failure
Records data.

Conditions for Clearing the MIL/DTC

D

The PCM will turn the MIL “OFF” on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condtion is no longer present.

D

A history DTC P1635 will clear after 40 cosecutive trip
cycle during which the warm up cycles have occurred
without a fault.

D

DTC P1635 can be cleared using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed. Tech2 “ Clear Info” function or by disconnecting
the PCM battery feed.

6E–443

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) 

P1635 Reference Voltage # 1 Circuit Fault

 

Step

Action

Value(s)

Yes

No

1

Was the “On-Board(OBD)System Check” performed?

—

Go to

 Step 2

Go to

 OBD

System

Check

2

1. Connect a DVM between the 5volt reference curcuit

and the TP1 and TP2 sensor ground curcuit.

2. Check the voltage using a DVM.

Is the voltage near the specified value?

5V

Varify repair

Go to

 Step 3

3

1. Check the TPS1and TPS2 5 volt reference curcuit.
2. If the curcuit is open or shorted, repair it as

necessary.

Was the curcuit open or short?

—

Varify repair

Go to

 Step 4

4

1. Check the TP1 and TP2 sensor ground curcuit.
2.  If the curcuit is open or shorted, repair it as

necessary.

Was the curcuit open or short?

—

Varify repair

Go to

 Step 5

5

1. Observe the battery voltage and circuit.
2. If a problem found, repair it as necessary.

Was a problem found?

—

Verify repair

Go to

 Step 6

6

Replace the PCM.

IMPORTANT: The replacement PCM must be
programmed.

Refer to ON–Vehicle Service in Power Control Module
and Sensors for procedures.

And also refer to latest Service Bulletin. Check to see
if the latest software is released or not.

And then Down Load the LATEST PROGRAMMED
SOFTWARE to the replacement PCM.

Is the adtion complete?

—

Verify repair

—

6E–444

6VE1 3.5 ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) P1636 PCM RAM Stack

Circuit Description

The powertrain control module (PCM) monitors
unexpected PCM reset. This will not turn on MIL light on,
only record code DTC P1636.

Conditions for Setting the DTC

D

Clock or COP (Computer Operating Properly) reset.

Action Taken When the DTC Sets

D

The PCM will not illuminate the malfunction indicator
lamp (MIL).

D

The PCM will store conditions which were present
when the DTC was set as Failure Records only. This
information will not be stored as Freeze Frame data.

Conditions for Clearing the MIL/DTC

D

The PCM will turn the MIL “OFF” on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condition is no longer present.

D

A history DTC P1636 will clear after 40 consecutive
warm-up cycles have occurred without a fault.

D

DTC P1636 can be cleared by using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed.

Diagnostic Aids

Check for the following conditions:

D

P1636 stored alone does not need diagnosis. Clear
DTC code.

DTC P1636 – PCM RAM Stack

 

Step

Action

Value(s)

Yes

No

1

Was the “On-Board Diagnostic (OBD) System Check”
performed?

—

Go to Step 2

Go to 

OBD

System

Check

2

1. Ignition is “ON”.
2. Install the Tech 2.
3. Start the engine and let it Idle.
4. On the Tech 2, select “DTC info”.

Does the Tech 2 indicate DTC P1636 failed?

—

Go to 

Step 3

Check the

Procedure

Refer to

Diagnostic

Aids

3

1. Ignition is “ON”.
2. Clear DTC P1636 by using the Tech 2 “Clear Info”.
3. Start the engine and let it Idle.
4. On the Tech 2, select “DTC info”.

Does the Tech 2 indicate DTC P1636 failed?

—

Go to 

Step 4

Check the

Procedure

Refer to

Diagnostic

Aids

4

1. Check for aftermarket electronics, such as

transceiver, stereos, and anti theft devices. They
may radiate EMI into the control system if they are
improperly installed. (This may cause a false sensor
reading and turn on the MIL.)

2. If a problem is found, repair as necessary.

Was a problem found?

—

Verify repair

—

6E–445

6VE1 3.5L ENGINE DRIVEABILITY AND EMISSIONS

Diagnostic Trouble Code (DTC) 

P1639 Reference Voltage # 2 Circuit Fault

D06RY00075

Circuit Description

The TP sensor # 1 shares a 5 Volt reference with the
PCM.
If the PCM detects the 5 Volt reference for the AP sensor
# 1 is failure, DTCP1635 will be set.

Conditions for setting the DTC

D

The ignition is “ON”.

D

The 5 Volt reference voltage for the AP sensor # 1 is
less than 4 volts.

D

The 5 Volt reference voltage for the AP sensor # 1 is
more than 5 volts.

Action Taken When the DTC Sets

D

The PCM will not illuminate the malfunction indicator
lamp (MIL) .

D

The PCM will store condition which were present when
the DTC was set as Freeze Frame and in the Failure
Records data.

Conditions for Clearing the MIL/DTC

D

The PCM will turn the MIL “OFF” on the third
consecutive trip cycle during which the diagnostic has
been run and the fault condtion is no longer present.

D

A history DTC P1639 will clear after 40 cosecutive trip
cycle during which the warm up cycles have occurred
without a fault.

D

DTC P1639 can be cleared using the Tech 2 “Clear
Info” function or by disconnecting the PCM battery
feed. Tech2 “ Clear Info” function or by disconnecting
the PCM battery feed.