Isuzu Amigo / Axiom / Trooper / Rodeo / VehiCross. Manual - part 442

7A1–78 TRANSMISSION CONTROL SYSTEM (4L30–E)

DTC P1850 Brake Band Apply Solenoid Malfunction  (Cont’d)

Step

No

Yes

Action

12

1. Disconnect the transmission main case connector E-42.
2. Using the J39200 DVOM, check continuity between the

terminals E42–7(B) and ground.

Is there a continuity?

Go to 

Step 13

Go to 

Step 17

13

The brake band apply solenoid is faulty, or the internal wiring
harness from the brake band apply solenoid is shorted to ground.

Was a problem found and corrected?

Go to 

Step 20

—

14

The wiring harness between the PCM connector terminal E35–43
and the transmission main case connector terminal E42–2(D) is
shorted to ground.

Was a problem found and corrected?

Go to 

Step 20

—

15

The wiring harness between the PCM connector terminal E35–43
and the transmission main case connector terminal E42–2(D) is
open.

Was a problem found and corrected?

Go to 

Step 20

—

16

The brake band apply solenoid is faulty, or the internal wiring
harness from the brake band apply solenoid is open.

Was a problem found and corrected?

Go to 

Step 20

—

17

The wiring harness between the PCM connector terminal E35–10
and the transmission main case connector terminal E42–7(B) is
shorted to ground.

Was a problem found and corrected?

Go to 

Step 20

—

18

The wiring harness between the PCM connector terminal E35–10
and the transmission main case connector terminal E42–7(B) is
open.

Was a problem found and corrected?

Go to 

Step 20

—

19

Check every connection at the PCM.
If OK, replace the PCM. Refer to 

Powertrain Control Module

(PCM) in Automatic Transmission (4L30–E) section.

Is the replacement complete?

Go to 

Step 20

—

20

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

then “Clear Info” function and ensure the following conditions
are met:

D

The brake band apply solenoid is commanded “on” and the
volts drop to zero.

D

The brake band apply solenoid is commanded “off” and the
volts increase to B+.

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)

7A1–79

DTC P1860 TCC PWM Solenoid Electrical

D07R200011

Circuit Description

The PCM allows current to flow through the solenoid coil
according to the duty cycle (percentage of “on” and “off”
time).  This current flow through the solenoid coil creates
a magnetic field that magnetizes the solid core.  The
magnetized core attracts the check ball to seat against
spring pressure.  This blocks the exhaust for the TCC
signal fluid and allows 2–3 drive fluid to feed to TCC signal
circuit.The TCC signal fluid pressure acts on the TCC
regulator valve to regulate line pressure and to apply fluid
pressure to the torque converter clutch shift control valve.
When the TCC shift valve is in the apply position,
regulated apply fluid pressure is directed through the TCC
valve to apply the torque converter clutch.  The TCC
PWM solenoid is used in conjunction with the TCC PWM
solenoid to regulate fluid to the torque converter.  The
TCC PWM solenoid is attached to the valve body within
the transmission.
This DTC detects a continuous open or short to ground or
ignition in the TCC circuit or the TCC PWM solenoid.  This
is a type “B” DTC.

Conditions For Setting The DTC

D

Battery voltage is between 10 and 16 volts.

D

No shift solenoid A DTCs P0751 or P0752 or P0753.

D

No shift solenoid B DTCs P0756 or P0757 or P0758.

D

Ignition is “on”, Engine “run”.

D

The PCM commands the solenoid “on” and the
voltage remains low (zero volts).

D

The PCM commands the solenoid “off” and the
voltage remains high (B+).

D

All conditions met for 0.875 

∼

 1.25 seconds.

Action Taken When The DTC Sets

D

Inhibit TCC engagement.

D

For lamp illuminate refer to 

DTC type definition (type

B).

Conditions For Clearing The MIL/DTC

D

The PCM will turn off the MIL and CHECK TRANS
Lamp after three consecutive ignition cycles without a
failure reported.

D

The DTC can be cleared from the PCM history by
using a scan tool.  

D

The DTC will be cleared from history when the vehicle
has achieved 40 warmup cycles without a failure
reported.

D

The PCM will cancel the DTC default actions when
the fault no longer exists and the ignition is cycled “off”
long enough to power down the PCM.

Diagnostic Aids

D

Inspect the wiring for poor electrical connections at
the PCM and at the transmission connector.  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.

Test Description

The numbers below refer to the step numbers on the
diagnostic chart

:

3. This test checks for voltage to the solenoid.
4. This test checks the ability of the PCM and wiring to

control the ignition circuit.

9. This test checks the resistance of the TCC solenoid

and the internal wiring harness.

7A1–80 TRANSMISSION CONTROL SYSTEM (4L30–E)

DTC P1860 TCC PWM Solenoid Electrical 

Step

Action

Yes

No

1

Were you sent here from the “Powertrain On–Board Diagnostic
(OBD) System Check”?

Go to 

Step 2

Go to 

OBD

System Check

Refer to

Driveability and

Emission in

Engine section

2

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

NOTE: Before clearing DTC(s), use the scan tool to record “Freeze
Frame” and “Failure Records” for reference, as data will be lost
when the“Clear Info” function is used.

3. Record the DTC “Freeze Frame” and “Failure Records”.

Was DTC P1860 set?

Go to 

Step 3

Go to 

Step 4

3

Using the J39200 DVOM, back probe between PCM connector
terminals E35–51 and E35–33.

Is the voltage 0?

Go to 

Step 5

Go to 

Step 6

4

1. Apply brake pedal and select transmission range “D”.
2. Do a test drive, and increase the vehicle speed to TCC “on” at

4th.

Does the scan tool display DTC P1860 at TCC “ON”?

Go to 

Step 9

Go to 

Diagnostic
Aids

5

1. Turn the ignition “off”.
2. Disconnect the E-35 (RED) PCM connector.
3. Using the J39200 DVOM, measure the resistance between

PCM connector terminals E35–51 and E35–33.

Is the resistance within 18 – 20 ohms?

Go to 

Step 7

Go to 

Step 8

6

The wiring harness between PCM connector terminal E35–51
and transmission adapter case connector terminal E40–1(A) is
shorted to voltage.

Was a problem found and corrected?

Go to 

Step 15

Go to 

Step 16

7

Intermittent condition.
Check the wiring harness and terminals between PCM connector
J2 and transmission adapter case connector E–40.

Was a problem found and corrected?

Go to 

Step 15

Go to 

Step 16

8

1. Disconnect the transmission adapter case connector E–40.
2. Using the J39200 DVOM, measure the resistance between

terminal E40–1(A) and ground.

Is the resistance within 18 – 20 ohms?

Go to 

Step 13

Go to 

Step 14

9

1. Turn the ignition “off”.
2. Disconnect the E-35 (RED) PCM connector.
3. Using the J39200 DVOM, measure the resistance between

terminals E35–51 and E35–33.

Is the resistance within 18 – 20 ohms?

Go to 

Step 15

Go to 

Step 10

10

1. Disconnect the transmission adapter case connector E–40.
2. Using the J39200 DVOM, measure the resistance between

terminal E40–1(A) and ground.

Is the resistance within 18–20 ohms?

Go to 

Step 11

Go to 

Step 12

11

The wiring harness between PCM connector E-35 and adapter
case connector E-40 is shorted to ground.

Was a problem found and corrected?

Go to 

Step 17

—

TRANSMISSION CONTROL SYSTEM (4L30–E)

7A1–81

DTC P1860 TCC PWM Solenoid Electrical  (Cont’d)

Step

No

Yes

Action

12

The TCC solenoid is faulty, or the internal wiring harness from the
TCC solenoid is shorted to ground.

Was a problem found and corrected?

Go to 

Step 17

—

13

The wiring harness between PCM connector terminal E35–51
and adapter case terminal E40–1(A) is open.

Was a problem found and corrected?

Go to 

Step 17

—

14

The TCC solenoid is faulty, or the internal wiring harness from the
TCC solenoid is open.

Was a problem found and corrected?

Go to 

Step 17

—

15

Check every connection at the PCM.
If OK, replace the PCM. Refer to 

Powertrain Control Module

(PCM) in Automatic Transmission (4L30–E) section.

Is the replacement complete?

Go to 

Step 17

—

16

Check the PCM connector terminal E35–51, and transmission
adapter case connector terminal E40–1(A).

Was a problem found and corrected?

Go to 

Step 17

—

17

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

then “Clear Info” function and ensure the following conditions
are met:

D

The TCC solenoid is commanded “on” and the volts increase
to B+.

D

The TCC solenoid is commanded “off” and the volts drop to
zero.

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