DTC P1825 or P1915
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Perform
the Diagnostic
System Check - Vehicle prior to using this diagnostic procedure. |
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Review
Strategy
Based Diagnosis for an overview of the diagnostic approach. |
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Diagnostic
Procedure Instructions provides an overview of each diagnostic category. |
DTC P1825:
Internal Mode Switch -
DTC P1915: Internal Mode Switch Start/Wrong Range
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Circuit |
Short to Ground |
Open/High Resistance |
Short to Voltage |
Signal Performance |
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P1825 |
P1915 |
P1915 |
P1825, P1915 |
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P1915 |
P1825 |
P1825 |
P1825, P1915 |
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P1915 |
P1825 |
P1825 |
P1825, P1915 |
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P1825 |
P1915 |
P1915 |
P1825, P1915 |
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Ground |
-- |
P1825 |
P1825 |
P1825, P1915 |
|
Circuit |
|
Short to Ground |
Open |
Short to Voltage |
|
Operating Conditions: Ignition ON, range
selector in Park |
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LOW |
LOW |
HI |
HI |
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HI |
LOW |
HI |
HI |
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HI |
LOW |
HI |
HI |
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LOW |
LOW |
HI |
HI |
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HI = 12 volts LOW = 0 volts |
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The internal mode
switch (IMS) assembly is a sliding contact switch attached to the control
valve body within the transmission. The 4 inputs to the transmission control
module (TCM) from the switch indicate which position is selected by the
transmission manual shaft. The input voltage at the TCM is high when the switch
is open and low when the switch is closed to ground. The state of each input is
displayed on the scan tool as IMS. The IMS input parameters represented are
transmission range signal A, Signal B, signal C, and signal P.
Conditions
for Running the DTC
No
P1825
Vehicle speed
sensor (VSS) is greater than 16 km/h (10 mph)
P1915
The transmission output
shaft speed is less than 90 RPM.
Conditions
for Setting the DTC
P1825
Any one or more of the
following conditions:
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The
IMS signal circuit A, B, or P are Low in Park for greater than 1 second. |
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The
IMS signal circuit A is Low in D6 for 8 seconds. |
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The
IMS signal circuit C is High in D6 for 8 seconds. |
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The
TCM detects an invalid range from the IMS for 3.25 seconds. |
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The
IMS signal circuit C is high in D6 for greater than 8 seconds and
the engine torque is greater than 20 N·m (15 lb ft). |
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Park/Neutral
Switch equals P/N and the IMS state is |
P1915
The manual shift shaft
switch assembly indicates a transitional state during the following sequence:
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The
engine speed is less than 50 RPM for more than 0.25 seconds. |
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The
engine speed is 50-480 RPM for more than 0.07 seconds. |
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The
engine speed is greater than 525 RPM for more than 3.25 seconds. |
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The
transmission input shaft speed is greater than 250 RPM. |
Action
Taken When the DTC Sets
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DTCs
P1825 and P1915 are Type A DTCs. |
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The
TCM commands maximum line pressure. |
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The
TCM turns OFF all solenoids. |
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The
TCM freezes transmission adaptive functions. |
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The
TCM defaults the transmission to third gear if the current gear is 1st, 2nd,
or 3rd; or fifth gear if the current gear is 4th, 5th, or 6th gear. |
Conditions
for Clearing the DTC
DTCs P1825 and P1915 are
Type A DTCs.
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The
IMS is part of a wire harness, which connects electrically to the control
solenoid (w/body and TCM) valve assembly and is serviced separately from the
control solenoid (w/body and TCM) valve assembly. Inspect the IMS, harness,
connector, and control solenoid (w/body and TCM) valve assembly pins for
metallic debris. Use the J 35616
GM-approved terminal test kit for any test that requires probing the control
solenoid (w/body and TCM) valve assembly harness connector or a component
harness connector. |
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Inspect
for a incorrectly adjusted range selector lever
cable. Refer to Range
Selector Lever Cable Adjustment . |
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Inspect
the manual shaft detent assembly for proper alignment with the manual shaft
detent lever. The manual shaft detent roller must be centered over the detent
lever and not contact the IMS actuator arm. |
Schematic
Reference
Automatic
Transmission Controls Schematics
Connector
End View Reference
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DTC
Type Reference
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Electrical
Information Reference
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Scan
Tool Reference
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Special
Tools Required
J 35616
GM-Approved Terminal Test Kit
Test for the correct
operation of the IMS. Refer to Transmission
Internal Mode Switch Logic .
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If
the IMS operation matches the IMS logic table, the system is functioning
normally. |
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If
a signal circuit displays LOW, the control solenoid (w/body and TCM) valve
assembly is faulty. |
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If
a signal circuit remains HI when connected to ground, the control solenoid
(w/body and TCM) valve assembly is faulty. |
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If
the above two tests indicate correct TCM functions, the IMS is faulty. |
|
Internal Mode Switch (IMS) Logic Table Gear Selector Position |
A |
B |
C |
P |
|
Park |
LOW |
HI |
HI |
LOW |
|
Park/Reverse |
LOW |
LOW |
HI |
LOW |
|
Reverse |
LOW |
LOW |
HI |
HI |
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Reverse/Neutral |
HI |
LOW |
HI |
HI |
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Neutral |
HI |
LOW |
HI |
LOW |
|
Neutral/Drive 6 |
HI |
LOW |
LOW |
LOW |
|
Drive 6 |
HI |
LOW |
LOW |
HI |
|
Drive 4 |
LOW |
LOW |
LOW |
LOW |
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Drive 3 |
LOW |
HI |
LOW |
HI |
|
Drive 2 |
HI |
HI |
LOW |
LOW |
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Invalid |
HI |
HI |
HI |
HI |
|
LOW |
HI |
HI |
HI |
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HI |
HI |
HI |
LOW |
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HI = Ignition voltage LOW = 0 voltage |
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Perform the Diagnostic
Repair Verification after completing the diagnostic procedure.
Important: Perform the Control
Solenoid Valve and Transmission Control Module Assembly Inspection for the
following components before replacing the components.
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Internal
Mode Switch (IMS) Replacement. Refer to Manual
Shift Shaft Position Switch Replacement . |
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Control
Solenoid (w/Body and TCM) Valve Assembly Replacement. Refer to Control
Module References for replacement, setup, and programming. |
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Perform
the Service
Fast Learn Adapts . |