Mechanics

CHEVY CODE SCANNER GIVES 2 CODES P0128 AND

2003 Chevrolet Trailblazer

Transmission problem
2003 Chevy Trailblazer 6 cyl Two Wheel Drive Automatic 95,000 miles

P0128 seems to be about the thermostat.

P0753 is my main concern symptoms does not seem to shift into last gear I am doing 70mph at 3500 rpm's
from research I see its silenoid A. I plan on taking it to have transmission serviced can I request they replace this or will it require a rebuild?
Or is this something I can replace on my own I am mechanical by nature but when it comes to transmission I dont want to mess it up.
Avatar
Mach2liquid
December 14, 2007.




Subject: MIL On, Transmission Stuck in Second or Third Gear, IPC Inoperative, DTCs P0740, P0753, P0758, P0785, P0787, P0973, P0976, P1860, P2761, P2764 and/or P2769 Set (Verify and Repair Source of Voltage Loss #01-07-30-002E - (09/23/2005)

Models: 2006 and Prior GM Passenger Cars and Light Duty Trucks

2005-2006 HUMMER H2

2006 HUMMER H3

2005-2006 Saab 9-7X

with 4L60-E, 4L65-E, 4L80-E or 4L85-E Automatic Transmission (RPOs M30, M32, M33, MT1, MN8)

This bulletin is being revised to update model years, add additional models and add additional diagnostic information. Please discard Corporate Bulletin Number 01-07-30-002D (Section 07 -- Transmission/Transaxle).

Condition
Some customers may comment on one or more of the following conditions: • The Malfunction Indicator Lamp (MIL) is ON.

• The transmission is defaulted to second gear (4L80/85-E).

• The transmission is defaulted to third gear (4L60/65-E).

• The instrument cluster is inoperative.

Upon investigation, one or all of the diagnostic trouble codes (DTCs) P0740, P0753, P0758, P0785, P0787, P0973, P0976, P1860, P2761, P2764 and P2769 may be set depending on the vehicle.

Cause
The most likely cause of this condition may be a loss of voltage to the transmission solenoid power supply circuit.

This condition may also be the result of an incorrect installation of an aftermarket electronic device such as a remote starter or alarm system.

Correction
Important: If the vehicle is equipped with an aftermarket electronic device and the DTCs are being set when the device is being used, verify that the appropriate fuse is being supplied battery voltage during operation. If voltage is not present at this fuse, these DTCs will be set due to lack of voltage at the solenoids. This condition is most likely to occur with an incorrectly installed remote starting system. If this is the case, refer the customer to the installer of the system for corrections. ANY REPAIRS DUE TO AFTERMARKET INSTALLATION OF ACCESSORIES IS A NON-WARRANTABLE ITEM.

With the ignition switch in the RUN position, test for battery voltage at the circuit fuse in the transmission solenoid power supply circuit. Refer to the appropriate SI Document for the transmission solenoid power supply circuit information.
If battery voltage is present at the fuse, inspect the ignition voltage circuit between the fuse and the transmission for possible opens.
If battery voltage is not present at the fuse, test for continuity between the fuse and the ignition switch. If NO continuity is between the fuse and the ignition switch, repair the open in that circuit.
If you have continuity between the fuse and the ignition switch, the most likely cause is the ignition switch. Replace the ignition switch using the appropriate Ignition Switch Replacement procedure in SI. Refer to group number 2.188 of the parts catalog for part description and usage of the ignition switch.

DTC P0128
Circuit Description
An engine coolant temperature (ECT) sensor monitors the temperature of the coolant. This input is used by the powertrain control module (PCM) for engine control and as an enabling criteria for some diagnostics.

The air flow coming into the engine is accumulated and used to determine if the engine has been driven within conditions that would allow the engine coolant to heat up normally to the thermostat regulating temperature. If the coolant temperature does not increase normally or does not reach regulating temperature of the thermostat, diagnostics that use ECT as enabling criteria may not run when expected.

This DTC will only run once per ignition cycle within the enabling condition. If the PCM detects the calibrated amount of air flow and engine run time have been met, and the ECT has not met the minimum thermostat regulating temperature, DTC P0128 sets.

Conditions for Running the DTC
• DTCs P0105, P0107, P0108, P0112, P0113, P0117, P0118, P0122, P0123, P0130, P0131, P0132, P0133, P0134, P0171, P0172, P0201, P0202, P0203, P0204, P0205, P0206, P0300, P0335, P0336, P0440, P0442, P0446, P0452, P0453, P0480, P0502 and P0503 for automatic transmission only, P0601, P0602, P0604, P0606, P0621, P1133, P1441 are not set.

• The engine coolant temperature is more than -39°C (-38°F), but less than 70°C (158°F).

• The intake air temperature is more than -7°C (+19°F).

• The engine is running between 30 seconds and 30 minutes.

• The vehicle has traveled more than 2.4 km (1.5 mi) at more than 40 km/h (25 mph).

• The mass air flow (MAF) calculated is more than 15 g/s.

Conditions for Setting the DTC
• The calibrated amount of engine run time has been met

• The calibrated amount of engine air flow has been met

• The calibrated ECT of 75°C (167°F) has not been met

Action Taken When the DTC Sets
The control module illuminates the malfunction indicator lamp (MIL) on the second consecutive ignition cycle that the diagnostic runs and fails.
The control module records the operating conditions at the time the diagnostic fails. The first time the diagnostic fails, the control module stores this information in the Failure Records. If the diagnostic reports a failure on the second consecutive ignition cycle, the control module records the operating conditions at the time of the failure. The control module writes the operating conditions to the Freeze Frame and updates the Failure Records.
Conditions for Clearing the MIL/DTC
• The control module turns OFF the malfunction indicator lamp (MIL) after 3 consecutive ignition cycles that the diagnostic runs and does not fail.

• A current DTC, Last Test Failed, clears when the diagnostic runs and passes.

• A history DTC clears after 40 consecutive warm-up cycles, if no failures are reported by this or any other emission related diagnostic.

• Clear the MIL and the DTC with a scan tool.

Step
Action
Values
Yes
No

Schematic Reference: Engine Controls Schematics

Connector End View Reference: Powertrain Control Module (PCM) Connector End Views or Engine Controls Connector End Views

1
Did you perform the Diagnostic System Check-Engine Controls?
--
Go to Step 2
Go to Diagnostic System Check - Engine Controls

2
Important: The cooling fans are commanded ON when certain engine coolant temperature (ECT) DTCs are set.

Is the cooling system coolant low?
--
Go to Draining and Filling Cooling System in Engine Cooling
Go to Step 3

3
Test and verify the proper operation of the thermostat. Refer to Thermostat Diagnosis in Engine Cooling.

Did you find and correct the condition?
--
Go to Step 14
Go to Step 4

4
Disconnect the ECT sensor.
Inspect for the following conditions: - Corrosion on the ECT sensor terminals

- Improper or corroded terminals at the ECT harness connector

- Loose terminals in the ECT harness connector. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 14
Go to Step 5

5
Measure the voltage from the signal circuit of the ECT sensor to a good ground with a DMM. Refer to Circuit Testing in Wiring Systems.

Is the voltage within the specified range?
4.8-5.2 V
Go to Step 6
Go to Step 8

6
Measure the voltage from the signal circuit of the ECT sensor to the low reference circuit of the ECT sensor with a DMM.

Is the voltage within the specified range?
4.8-5.2 V
Go to Step 9
Go to Step 7

7
Test the ECT sensor low reference circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 14
Go to Step 11

8
Test the ECT sensor signal circuit for high resistance. Refer to Circuit Testing and Wiring Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 14
Go to Step 11

9
Turn OFF the ignition.
Remove the ECT sensor. Refer to Engine Coolant Temperature (ECT) Sensor Replacement.
Place the sensor on a work surface away from any heat source.
Allow the sensor to reach the ambient air temperature for 30-60 minutes.
Observe and record the ambient air temperature of the vehicle environment using an accurate thermometer.
Measure the resistance of the ECT sensor and record the value.
Compare the resistance measurement of the ECT sensor to the ambient air temperature on the Temperature vs. Resistance table. Refer to Temperature vs Resistance.
Did you complete the replacement?
--
Go to Step 10
Go to Step 12

10
Install the ECT sensor. Refer to Engine Coolant Temperature (ECT) Sensor Replacement.

Is the action complete?
--
Go to Intermittent Conditions
--

11
Test for an intermittent and for a poor connection at the PCM. Refer to Testing for Intermittent Conditions and Poor Connections and Connector Repairs in Wiring Systems.

Did you find and correct the condition?
--
Go to Step 14
Go to Step 13

12
Replace the ECT sensor. Refer to Engine Coolant Temperature (ECT) Sensor Replacement.

Did you complete the replacement?
--
Go to Step 14
--

13
Replace the PCM. Refer to Powertrain Control Module (PCM) Replacement.

Did you complete the replacement?
--
Go to Step 14
--

14
Clear the DTCs with a scan tool.
Turn OFF the ignition for 30 seconds.
Start the engine.
Operate the vehicle within the Conditions for Running the DTC. You may also operate the vehicle within the conditions that you observed from the Freeze Frame/Failure Records.
Did the DTC fail this ignition?
--
Go to Step 2
Go to Step 15

15
Observe the Capture Info. With a scan tool.

Are there any DTCs that have not been diagnosed?
--
Go to Diagnostic Trouble Code (DTC) List
System OK

Dennyp
Dec 16, 2007.


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