Content .. 98 99 100 101 ..

Isuzu engine C22NE / 22LE / 20LE. Manual - part 100

DRIVEABILITY AND EMISSIONS 6E1-229

0.5

B/R

0.5

Engine

Control

Module

(ECM)

Crank

Angle

Sensor

Tacho

Meter

Fuse

15A

DIAGNOSTIC TROUBLE CODE (DTC) (Flash DTC = 91)

TACHO OUT LOW ERROR

Circuit Description

Based on the information from the Crank Position

Sensor (CKP), X58 reference signal is generated at

each rotation of the crankshaft.

Engine Control Module (ECM) converts X58 reference

signal into rectangle wave and delivers it as output

signal to drive the pulse motor of the crankshaft.

When the wave length of the output signal is long, the

tacho meter indicates the engine speed is low, and

vise versa.

This malfunction detects a low impedance short to

ground or open contact on the Tacho output, the

Diagnostic Trouble Code 91 will be set.

Conditions for Setting the DTC

• Driver feedback information shows a low state at its

operation even when commanded low.

Action Taken When the DTC Sets

• The ECM will turn ON the Malfunction Indicator

Lamp

Conditions for Clearing the DTC

Once the ECM determines that a fault(s) has been

rectified then the CEL will switch OFF, although the

fault code will remain in the ECM memory.

Any fault codes will remain in ECM memory until -

1. They are cleared by disconnecting the Battery for

more than 30 seconds.

2. A service tool such as Tech 2 is used to clear them.

3. Ten consecutive starts without logging a fault.

Diagnostic Aids

• Poor connections or a damaged harness - Inspect

the harness connections for: backed out terminals,

imprope, mating or damaged terminals. Also check

for open circuit, short to ground, and short to

voltage.

6E1-230 DRIVEABILITY AND EMISSIONS

• This malfunction detects a low impedance short to

ground or open contact on the ECM out put circuit.

DTC (Flash DTC = 91)

Tacho Out Low Error

Step

Action

Value(s)

Yes

Was the "On-Board Diagnostic (OBD) System Check"

performed?

Go to Step 2

Go to OBD

System Check

1. Ignition OFF.

2. Check for a faulty connection or damaged terminals at

the ECM connector.

Was a problem found?

Verify repair

Go to Step 3

Check for a faulty connection or damaged terminals at the

ECM connector.

Was a problem found?

Verify repair

Go to Step 4

1. Check for an open or short to ground in the circuit

between the meter cluster connector and the ECM

connector.

If a problem is found, repair as necessary.

Verify repair

Go to Step 5

1. Check for an open circuit between the meter cluster

connector and the ground.

If a problem is found, repair as necessary.

Verify repair

Go to Step 6

1. Check for an open circuit between the meter cluster

and battery feed.

If a problem is found, repair as necessary.

Verify repair

Go to Step 7

1. Disconnect the meter cluster Panel.

2. Check the tacho meter circuit for an open.

Was a problem found?

Go to Step 5

Go to Step 9

1. Disconnect the ECM and CKP sensor.

2. Check for an open in the 58X reference circuit between

the connector and the ECM harness connector.

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

Was a problem found?

Verify repair

Go to Step 9

1. Reconnect the ECM and CKP sensor.

2. Connect a Digital Voltmeter (DVM) to measure voltage

on the 58X reference circuit at the ECM connector.

3. Observe the voltage while cranking the engine.

Is the voltage near the specified value?

2.5V

Go to Step 12

Go to Step 10

Check the connections at the CKP sensor and replace the

terminals if necessary.

Did any terminals require replacement?

Verify repair

Go to Step 11

Replace the CKP sensor.

Is the action complete?

Verify repair

Check connections at the ECM and replace the terminals

if necessary.

Did any terminals require replacement?

Verify repair

Go to Step 13

Replace the EPROM or ECM.

Is the action complete?

Note) Refer to 6E1-243.

Verify repair

DRIVEABILITY AND EMISSIONS 6E1-231

0.5

B/R

0.5

Engine

Control

Module

(ECM)

Crank

Angle

Sensor

Tacho

Meter

Fuse

15A

DIAGNOSTIC TROUBLE CODE (DTC) (Flash DTC =92)

TACHO OUT HIGH ERROR

Circuit Description

Based on the information from the Crank Position

Sensor (CKP), X58 reference signal is generated at

each rotation of the crankshaft.

Engine Control Module (ECM) converts X58 reference

signal into rectangler wave and delivers it as output

signal to drive the pulse motor of the crankshaft.

When the wave length of the output signal is long, the

tacho meter indicates the engine speed is low, and

vise versa.

This malfunction detects a low impedance short to

battery or on the Tacho output, then Diagnostic

Trouble Code 92 will be set.

Conditions for Setting the DTC

• Driver feedback information shows a low state at its

operation even when commanded low.

Action Taken When the DTC Sets

• The ECM will turn ON the Malfunction Indicator

Lamp

Conditions for Clearing the DTC

Once the ECM determines that a fault(s) has been

rectified then the CEL will switch OFF, although the

fault code will remain in the ECM memory.

Any fault codes will remain in ECM memory until -

1. They are cleared by disconnecting the Battery for

more than 30 seconds.

2. A service tool such as Tech 2 is used to clear them.

3. Ten consecutive starts without logging a fault.

Diagnostic Aids

• Poor connections or a damaged harness - Inspect

the harness connections for: backed out terminals,

imprope, mating or damaged terminals. Also check

for open circuit, and short to battery.

6E1-232 DRIVEABILITY AND EMISSIONS

DTC (Flash DTC = 92)

Tacho Out High Error

Step

Action

Value(s)

Yes

Was the "On-Board Diagnostic (OBD) System Check"

performed?

Go to Step 2

Go to OBD

System

Check

1. Ignition OFF.

2. Check for a faulty connection or damaged terminals at

the tacho meter connector.

Was a problem found?

Verify repair

Go to Step 3

Check for a faulty connection or damaged terminals at the

ECM connector.

Was a problem found?

Verify repair

Go to Step 4

Check for a short circuit between the meter cluster

connector and the ECM.

If a problem is found, repair the wire harness.

Is there still a problem?

Verify repair

Go to Step 5

1. Disconnect the ECM.

2. Check the ignition control circuit for a short to voltage.

Was a problem found?

Verify repair

Go to Step 6

Replace the meter cluster.

Verify repair.

Is there still a problem?

Go to Step 8

Refer to CKP

Sensor Signal

Incorrect

1. Disconnect the ECM and CKP sensor.

2. Check for a short to ground in the 58X reference circuit

between the CKP sensor connector and the ECM

harness connector.

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

Was a problem found?

Verify repair

Go to Step 8

1. Reconnect the ECM and CKP sensor.

2. Connect a Digital Voltmeter (DVM) to measure voltage

on the 58X reference circuit at the ECM connector.

3. Observe the voltage while cranking the engine.

Is the voltage near the specified value?

2.5V

Go to Step 11

Go to Step 9

Check the connections at the CKP sensor and replace the

terminals if necessary.

Did any terminals require replacement?

Verify repair

Go to Step 10

Replace the CKP sensor.

Is the action complete?

Verify repair

Check connections at the ECM and replace the terminals

if necessary.

Did any terminals require replacement?

Verify repair

Go to Step 12

Replace the EPROM or ECM.

Is the action complete?

Note) Refer to 6E1-243.

Verify repair

Content .. 98 99 100 101 ..