Isuzu KB P190. Manual - part 1092

7A2-84 TRANSMISSION CONTROL SYSTEM (JR405E)

DTC P1863 (Flash Code 28)

Circuit Description

The high clutch transmission fluid pressure (TFP)
switch is installed to the lower part of the valve body
assembly and it feedbacks fluid pressure in the high
clutch hydraulic circuit. When the solenoid valve is
energized, fluid pressure is drained to disengage the
high clutch and the TFP switch is OFF. When the
solenoid valve is not energized, fluid pressure is
applied to engage the high clutch and the TFP switch is
ON. The TCM monitors the high clutch TFP switch ON/
OFF status through the signal circuit. If the TCM
detects an improper status on the signal circuit, this
DTC will set.

Condition for Running the DTC

• DTCs P0560, P0705, P0717, P0722, P0753,

P0758, P0763, P0768, P1120, P1750, P1755 and
P1875 are not set.

AND following conditions are met for longer than 3
seconds.

• The ignition switch is ON.

• The transmission fluid temperature is more than

°C (140°F).

• The engine speed is more than 500 RPM.

• The TCM is not under gearshift control.

Condition for Setting the DTC

Either of following condition is met:

• The TCM detects that the high clutch TFP switch

signal is stuck at the ON for longer than 2 seconds
when the selector lever in P, R or N range.

• The TCM detects that the high clutch TFP switch

signal is stuck at the OFF for longer than 2 second
when the selector lever in D range with 4th gear.

Action Taken When the DTC Sets

• The TCM blinks the Check Trans lamp when the

diagnostic runs and fails.

Condition for Clearing the DTC

• The TCM turns OFF the Check Trans lamp when

the diagnostic runs and does not fail.

• A current DTC clears when the diagnostic runs and

does not fail.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

• Use the Clutch, Brake, Solenoid and Pressure

Switch Logic table to verify each component works
properly within the selected gear range.

• A sticking or intermittently sticking the high clutch

solenoid valve will cause this DTC to set.

Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views

Circuit/ System Testing DTC P1863

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check -
Transmission Controls?

—

Go to Step 2

Go to Diagnostic

System Check -

Transmission

Controls

Install a scan tool.

Turn OFF the ignition for 30 seconds.

Lift the driving wheels or drive the vehicle
while observing the DTC Information with a
scan tool.

Is DTC P0763 also set?

—

Go to DTC P0763

Go to Step 3

Place the selector lever in forward range while
observing the High Clutch Pressure Switch
parameter with a scan tool.

Does the High Clutch Pressure Switch parameter
ever indicate OFF when gear is positioned 3rd and
4th?

—

Go to Step 5

Go to Step 4

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-85

Place the selector lever in P, R and N range while
observing the High Clutch Pressure Switch
parameter with a scan tool.

Does the High Clutch Pressure Switch parameter
indicate OFF?

—

Go to Diagnostic

Aids

Go to Step 5

Turn OFF the ignition.

Disconnect the in-line harness connector (E-
54) near the transmission range switch.

Turn ON the ignition, with the engine OFF.

Observe the high clutch Switch parameter
with a scan tool while momentarily jumping 3-
amp fused jumper wire between pin 1 of E-54
(female side) and a known good ground.

Does the scan tool indicate ON when the circuit is
jumpered and OFF when the circuit is not
jumpered?

—

Go to Step 8

Go to Step 6

Test the signal circuit between the TCM (pin
20 of C-95) and the in-line harness connector
(pin 1 of E-54 female side) for the following
conditions:

• An open circuit

• A short to ground

• High resistance

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 7

Turn OFF the ignition.

Disconnect the TCM harness connector.

Inspect for an intermittent and for a poor
connection at the harness connector of the
TCM (pin 20 of C-95).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 12

Inspect for an intermittent and for a poor
connection at the in-line harness connector
(pin 1 of E-54).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 9

Step

Action

Value(s)

Yes

7A2-86 TRANSMISSION CONTROL SYSTEM (JR405E)

Remove the transmission oil pan. Refer to
repair instructions (On-Vehicle Service).

Inspect the high clutch solenoid valve and
transmission fluid pressure (TFP) switch for
the following conditions:

• Physical damage

• Loose or improper installation

Inspect for an intermittent and for a poor
connection at the harness connector of the
high clutch TFP switch or in-line harness
connector.

Test the signal circuit between the high clutch
TFP switch and the in-line harness connector
(pin 1 of E-54 male side) for the following
conditions:

• An open circuit

• A short to ground

• A short to the solenoid valve circuit

• High resistance

Repair the connection(s), circuit(s) or replace
as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 10

Remove the high clutch solenoid valve and
TFP switch from the valve body assembly and
perform function check. Refer to repair
instructions (On-Vehicle Service).

Repair or replace as necessary.

Did you find and correct the condition?

—

Go to Step 13

Go to Step 11

Repair or replace the valve body assembly. Refer
to repair instructions (On-Vehicle Service or Unit
Repair).

Did you complete the repair or replacement?

—

Go to Step 13

—

Important: Replacement TCM must be
programmed.
Replace the TCM. Refer to TCM Replacement.

Did you complete the replacement?

—

Go to Step 13

—

Reconnect all previously disconnected
components or harness connector(s).

Clear the DTCs with a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

Drive the vehicle while observing the DTC
Information with a scan tool.

Did the DTC fail this ignition?

—

Go to Step 2

Go to Step 14

Observe the DTC Information with a scan tool.

Are there any DTCs that you have not diagnosed?

—

Go to DTC List

System OK

Step

Action

Value(s)

Yes

TRANSMISSION CONTROL SYSTEM (JR405E) 7A2-87

DTC P1875 (Flash Code 25)

Circuit Description

The all shift solenoid valves feed drive voltage from the
TCM and low side circuit is connected to the TCM
through the ground return circuit. The TCM monitors
the ground return circuit through the feedback circuit. If
the TCM detects an improper status on the ground
return circuit, this DTC will set.

Condition for Running the DTC

• The ignition switch is ON.

Condition for Setting the DTC

• The TCM detects an open circuit on the ground

return circuit.

Action Taken When the DTC Sets

• The TCM blinks the Check Trans lamp when the

diagnostic runs and fails.

• The TCM stops all shift solenoid valves and fixes

to the 3rd gear. If a fail-safe valve problem is
detected, the shift solenoid valves are not stopped
but gear is fixed to the 3rd gear.

• The TCM stops PC solenoid valve.

• The TCM inhibits lock up control.

Condition for Clearing the DTC

• The TCM turns OFF the Check Trans lamp when

the diagnostic runs and does not fail at next
ignition cycle.

• A current DTC clears when the diagnostic runs and

does not fail at next ignition cycle.

Diagnostic Aids

• If an intermittent condition is suspected, refer to

Intermittent Conditions in this section.

Schematic Reference: Transmission Controls
Schematics
Connector End View Reference: Transmission
Controls Connector End Views or TCM Connector End
Views

Circuit/ System Testing DTC P1875

Step

Action

Value(s)

Yes

Did you perform the Diagnostic System Check -
Transmission Controls?

—

Go to Step 2

Go to Diagnostic

System Check -

Transmission

Controls

Install a scan tool.

Turn OFF the ignition for 30 seconds.

Start the engine.

Monitor the DTC Information with a scan tool.

Does the DTC fail this ignition?

—

Go to Step 3

Go to Diagnostic

Aids

Turn OFF the ignition.

Disconnect the in-line harness connector (E-
54) near the transmission range switch.

Connect a test lamp between the ground
return circuit (pin 11 of E-54 male side) and
battery voltage.

Does the test lamp illuminate?

—

Go to Step 4

Go to Step 7

Inspect for an intermittent and for a poor
connection at the in-line harness connector
(pin 11 of E-54).

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 9

Go to Step 5

Test the circuit between the TCM (pin 22 of C-
95) and the in-line harness connector (pin 11
of E-54 female side) for an open circuit or high
resistance.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 9

Go to Step 6

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