Isuzu Rodeo UE. Manual — part 490
TRANSMISSION CONTROL SYSTEM (4L30–E)
7A1–79
DTC P1850 Brake Band Apply Solenoid Malfunction
D07RW014
Circuit Description
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The brake band apply solenoid is a normally open
solenoid which controls the flow of fluid for brake band
application. The Powertrain Control Module (PCM)
uses Pulse Width Modulation (PWM) and changes
the duty cycle to control the solenoid. The PCM turns
the solenoid on (energized) and off (deenergized) at a
constant frequency. The length of time the solenoid is
energized during each on/off cycle is called the pulse
width. By varying or “modulating” the pulse width, the
solenoid output pressure is changed. Since the
solenoid is normally open, increasing the pulse width
increases the duty cycle and decreases the output
pressure. PWM control provides smooth band
application without an accumulator. The band is only
applied in first and second gears.
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In the event of an electrical failure (open), the
solenoid regulates at the maximum oil flow (0% duty
cycle).
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The solenoid is activated by a current. This current is
produced by applying a voltage to one side (the High
side) and a ground to the other side (Low side).
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The High Side Driver (HSD) is a circuit of the PCM
that acts as a switch between the solenoids and the
supply voltage. The High side of the solenoid is
permanently supplied with voltage. When the ignition
is off, the HSD is turned off.
This DTC detects a continuous open or short to ground in
the brake band apply solenoid circuit or the brake band
apply solenoid. This is a type “D” DTC.
Conditions For Setting The DTC
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Battery voltage is between 10 and 16 volts.
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Ignition is “on”, Engine “run”.
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The PCM commands the solenoid “on” and the
voltage remains high (B+), or the PCM commands
the solenoid “off” and the voltage remains low (zero
volts).
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All conditions met in 1.3 seconds.
Action Taken When The DTC Sets
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Inhibit brake band apply solenoid.
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The PCM will not illuminate the Malfunction Indicator
Lamp (MIL).
Conditions For Clearing The DTC
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The DTC can be cleared from the PCM history by
using a scan tool.
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The DTC will be cleared from history when the vehicle
has achieved 40 warmup cycles without a failure
reported.
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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.
7A1–80 TRANSMISSION CONTROL SYSTEM (4L30–E)
Diagnostic Aids
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Inspect the wiring for poor electrical connection at the
PCM and at the transmission 16–way 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.
f
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 power to the brake band apply
solenoid from the ignition through the PCM.
4. This test checks the resistance of the transmission
internal wiring harness and brake band apply
solenoid.
5. This test checks the ability of the PCM and wiring to
control the ground circuit.
DTC P1850 Brake Band Apply Solenoid Malfunction
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”.
Were DTCs P0753, P0758 set?
Go to Step 3
Go to Step 4
3
Using the J39200 DVOM, back probe between PCM connector
terminals C3–E14 and C2–C8.
Is the voltage between 10 to 12 volts?
Go to Step 5
Go to Step 6
4
1. Turn the ignition “off”.
2. Disconnect the C1 (RED) and C3 (BLUE) PCM connectors.
3. Using the J39200 DVOM, measure the resistance between
PCM connector terminals C1–A16 and C3–E14.
Is the resistance within 10–12 ohms?
Go to Step 12
Go to Step 13
5
Using the J39200 DVOM, back probe between PCM connector
terminals C1–A16 and C2–C8.
Is the voltage between 10 to 12 volts?
Go to Step 26
Go to Step 4
6
1. Turn the ignition “off”.
2. Disconnect the C1 (RED) and C3 (BLUE) PCM connectors.
3. Using the J39200 DVOM, check continuity between PCM
terminal C3–E14 and ground.
Is there a continuity?
Go to Step 7
Go to Step 9
7
1. Disconnect the transmission 16–way connector H–10.
2. Using the J39200 DVOM, check continuity between connector
H10–7 and ground.
Is there a continuity?
Go to Step 8
Go to Step 17
8
1. Disconnect the transmission main case connector M–7.
2. Using the J39200 DVOM, check continuity between the
terminal M7–2(B) and ground.
Is there continuity?
Go to Step 18
Go to Step 19
TRANSMISSION CONTROL SYSTEM (4L30–E)
7A1–81
DTC P1850 Brake Band Apply Solenoid Malfunction (Cont’d)
Step
No
Yes
Action
9
1. Disconnect the J1 (RED) PCM Connector.
2. Using the J39200 DVOM, measure the resistance between
the PCM connector terminals C1–A16 and C3–E14.
Is the resistance within 10–12 ohms?
Go to Step 26
Go to Step 10
10
1. Disconnect the transmission 16–way connector H–10.
2. Using the J39200 DVOM, measure the resistance between
the terminal H10–7 and H10–5.
Is the resistance within 10–12 ohms?
Go to Step 17
Go to Step 11
11
1. Disconnect the transmission main case connector M–7.
2. Using the J39200 DVOM, measure the resistance between
the terminals M7–2(B) and M7–4(C).
Is the resistance within 10–12 ohms?
Go to Step 20
Go to Step 21
12
Using the J39200 DVOM, check continuity between PCM
terminal C1–A16 and ground.
Is there continuity?
Go to Step 14
Go to Step 26
13
1. Disconnect the transmission 16–way connector H–10.
2. Using the J39200 DVOM, measure the resistance between
the terminal H10–7 and H10–5.
Is the resistance within 10–12 ohms?
Go to Step 24
Go to Step 15
14
1. Disconnect the transmission 16–way connector H–10.
2. Using the J39200 DVOM, check continuity between terminal
H10–7 and ground.
Is there a continuity?
Go to Step 16
Go to Step 22
15
1. Disconnect the transmission main case connector M–7.
2. Using the J39200 DVOM, measure the resistance between
the terminals M7–2(B) and M7–4(C).
Is the resistance within 10–12 ohms?
Go to Step 25
Go to Step 21
16
1. Disconnect the transmission main case connector M–7.
2. Using the J39200 DVOM, check continuity between terminal
M7–2(B) and ground.
Is there a continuity?
Go to Step 18
Go to Step 23
17
The wiring harness between PCM terminal C3–E14 and
transmission 16–way connector terminal H10–5 is open.
Was a problem found and corrected?
Go to Step 27
—
18
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 27
—
19
The wiring harness between the transmission 16–way connector
terminal H10–5 and the transmission main case connector
terminal M7–4(C) is shorted to ground.
Was a problem found and corrected?
Go to Step 27
—
20
The wiring harness between the transmission 16–way connector
terminal H10–5 and the transmission main case connector
terminal M7–4(C) is open.
Was a problem found and corrected?
Go to Step 27
—
21
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 27
—
7A1–82 TRANSMISSION CONTROL SYSTEM (4L30–E)
DTC P1850 Brake Band Apply Solenoid Malfunction (Cont’d)
Step
No
Yes
Action
22
The wiring harness between the PCM connector terminal C1–A16
and transmission 16–way connector terminal H10–7 is shorted to
ground.
Was a problem found and corrected?
Go to Step 27
—
23
The wiring harness between the transmission 16–way connector
terminal H10–7 and the transmission main case connector
terminal M7–2(B) is shorted to ground.
Was a problem found and corrected?
Go to Step 27
—
24
The wiring harness between the PCM connector terminal C1–A16
and the 16–way connector terminal H10–7 is open.
Was a problem found and corrected?
Go to Step 27
—
25
The wiring harness between the transmission 16–way connector
terminal H10–7 and the transmission main case connector
terminal M7–2(B) is open.
Was a problem found and corrected?
Go to Step 27
—
26
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 27
—
27
1. After the repair is complete, use the scan tool to select “DTC”,
then “Clear Info” function and ensure the following conditions
are met:
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The brake band apply solenoid is commanded “on” and the
volts drop to zero.
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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
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