Isuzu KB P190. Manual - part 1093

7A2-88   TRANSMISSION CONTROL SYSTEM (JR405E)

6

1.

Turn OFF the ignition. 

2.

Disconnect the TCM harness connector. 

3.

Inspect for an intermittent and for a poor
connection at the harness connector of the
TCM (pin 22 of C-95). 

4.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 9

Go to Step 8

7

1.

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

2.

Inspect for an intermittent and for a poor
connection at the ground terminal or in-line
harness connector. Clean or tighten grounds
as necessary. 

3.

Repair the open circuit or high between the
ground terminal and the in-line harness
connector (pin 11 of E-54 male side).

Did you complete the repair?

—

Go to Step 9

—

8

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

Did you complete the replacement?

—

Go to Step 9

—

9

1.

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

2.

Clear the DTCs with a scan tool.

3.

Turn OFF the ignition for 30 seconds. 

4.

Start the engine.

Did the DTC fail this ignition?

—

Go to Step 3

Go to Step 10

10

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

No

TRANSMISSION CONTROL SYSTEM (JR405E)   7A2-89

Check Trans Lamp Inoperative, Always On or Always Blinking 

Circuit Description

The Check Trans Lamp is located on the instrument
panel (IP) cluster. The Check Trans Lamp informs the
driver that a transmission control system fault has
occurred and that system requires service. The ignition
voltage is supplied to the Check Trans Lamp via meter
fuse. The TCM turns ON by grounding the lamp control
circuit. 

Check Trans Lamp Illumination 

• The Check Trans Lamp illuminates for

approximately 3 seconds when the ignition switch
is turned ON, with the engine OFF.

• The Check Trans Lamp blinks if the TCM detects a

fault. 

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

Circuit/ System Testing Check Trans Lamp Inoperative, Always On or Always Blinking

Step

Action

Value(s)

Yes

No

1

Did you perform the Diagnostic System Check -
Transmission Controls?

—

Go to Step 2

Go to Diagnostic 

System Check -

Transmission 

Controls

2

1.

Verify whether the instrument panel (IP)
cluster is operational.

2.

Turn OFF the ignition for 30 seconds.

3.

Turn ON the ignition, with the engine OFF.

Does the check trans lamp turn ON then turn OFF
after 3 seconds passed? 

—

Go to Intermittent 

Conditions

Go to Step 3

3

Does the check trans lamp blink?

—

Check for DTCs and 

if none exist Go to 

Step 4

Go to Step 6

4

1.

Install a scan tool.

2.

Turn ON the ignition, with the engine OFF.

3.

Observe the Diagnostic Switch parameter with
a scan tool. 

Does the Diagnostic Switch parameter indicate
ON?

—

Go to Step 5

Check for DTCs

5

Repair the short to ground between the TCM (pin
18 of C-94) and the data link connector (DLC) (pin
11 of B-58).

Did you complete the repair?

—

Go to Step 21

—

6

1.

Perform the Check Light control with a scan
tool.

2.

Command the lamp ON and OFF.

Does the check trans lamp turn ON and OFF with
each command?

—

Go to Intermittent 

Conditions

Go to Step 7

7

1.

Turn OFF the ignition.

2.

Inspect the Meter (10A) fuse in the cabin fuse
block.

Is the Meter (10A) fuse open?

—

Go to Step 8

Go to Step 9

7A2-90   TRANSMISSION CONTROL SYSTEM (JR405E)

8

Replace the Meter (10A) fuse. If the fuse continues
to open, repair the short to ground on one of the
circuits that is fed by the Meter (10A) fuse or
replace the shorted attached component.

Did you complete the repair?

—

Go to Step 21

—

9

1.

Turn OFF the ignition.

2.

Disconnect the TCM C-94 harness connector.

3.

Turn ON the ignition, with the engine OFF.

Is the check trans lamp OFF?

—

Go to Step 10

Go to Step 16

10

1.

Remove the Meter (10A) fuse that supplies
voltage to the Check Trans Lamp.

2.

Turn ON the ignition, with the engine OFF.

3.

Measure the voltage from the check trans
lamp control circuit in the TCM harness
connector (pin 20 of C-94) to a known good
ground.

Is the voltage less than the specified value?

1 volt

Go to Step 11 

Go to Step 17

11

1.

Turn OFF the ignition.

2.

Reinstall the Meter (10A) fuse.

3.

Turn ON the ignition, with the engine OFF.

4.

Connect a 3-amp fused jumper wire between
the TCM harness connector (pin 20 of C-94)
and a known good ground.

Is the check trans lamp illuminated?

—

Go to Step 15

Go to Step 12

12

1.

Turn OFF the ignition.

2.

Remove the IP cluster.

3.

Connect a test lamp between the ignition
voltage feed circuit of the IP cluster harness
connector (pin 8 of B-24) and a known good
ground.

4.

Turn ON the ignition, with the engine OFF.

Does the test lamp illuminate?

—

Go to Step 13

Go to Step 18 

13

1.

Test the control circuit between the TCM (pin
20 of C-94) and the IP cluster (pin 25 of B-23)
for an open circuit or high resistance.

2.

Repair the circuit(s) as necessary.

Did you find and correct the condition?

—

Go to Step 21

Go to Step 14

14

1.

Inspect for an intermittent and for poor
connections at the harness connector of the
IP cluster (pin 25 of B-23 and pin 8 of B-24).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 21

Go to Step 19

15

1.

Inspect for an intermittent and for a poor
connection at the harness connector of the
TCM (pin 20 of C-94).

2.

Repair the connection(s) as necessary.

Did you find and correct the condition?

—

Go to Step 21

Go to Step 20

16

Repair the short to ground between the TCM (pin
20 of C-94) and the IP cluster (pin 25 of B-23).

Did you complete the repair?

—

Go to Step 21

—

Step

Action

Value(s)

Yes

No

TRANSMISSION CONTROL SYSTEM (JR405E)   7A2-91

17

Repair the short to battery or ignition voltage
between the TCM (pin 20 of C-94) and the IP
cluster (pin 25 of B-23).

Did you complete the repair?

—

Go to Step 21

—

18

Repair the open circuit or high resistance on
ignition the voltage feed circuit between the Meter
(10A) fuse and the IP cluster (pin 8 of B-24).

Did you complete the repair?

—

Go to Step 21

—

19

Repair or replace the IP cluster.

Did you complete the repair or replacement?

—

Go to Step 21

—

20

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

Did you complete the replacement?

—

Go to Step 21

—

21

1.

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

2.

Perform the Check Light control with a scan
tool.

3.

Command the lamp ON and OFF.

Does the check trans lamp turn ON and OFF with
each command?

—

System OK

Go to Step 7

Step

Action

Value(s)

Yes

No