P150C

DTC P15OC

Diagnostic Instructions

^ Perform the Diagnostic System Check - Vehicle prior to using this diagnostic procedure.
^ Review Strategy Based Diagnosis for an overview of the diagnostic approach
^ Diagnostic Procedure Instructions provides an overview of each diagnostic category

DTC Descriptor

DTC P15OC: Transmission Control Module (TCM) Engine Speed Request Circuit

Diagnostic Fault Information






Circuit/System Description

Modules connected to the high and low speed GMLAN serial data circuits monitor for serial data communications during normal vehicle operation. Operating information and commands are exchanged among the modules. The modules have prerecorded information about what messages are needed to be exchanged on the serial data circuits for each virtual network. The messages are supervised and periodic messages are used by the receiver module as an availability indication of the transmitter module. Each message contains the identification number of the transmitter module.

Conditions for Running the DTC

^ The system voltage is between 9-16 volts.
^ The vehicle power mode requires serial data communications.

Conditions for Setting the DTC

A supervised periodic message that includes the transmitter module availability has not been received or is intermittently missing.

Action Taken When the DTC Sets

DTC P15OC is a Type C DTC.

Conditions for Clearing the DTC

DTC P15OC is a Type C DTC.

Diagnostic Aids

Use the DTC Descriptor list to determine the module which is not communicating. If there are multiple non-communicating modules in series on high speed GMLAN, choose the one closest to the data link connector (DLC) for this diagnostic.

Reference Information

Schematic Reference

Data Link Connector Schematics

Connector End View Reference

Computer/Integrating Systems Connector End Views

Electrical Information Reference

^ Circuit Testing
^ Connector Repairs
^ Testing for Intermittent Conditions and Poor Connections
^ Wiring Repairs

Circuit/System Verification

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 data.

Circuit/System Testing

1. Using the DTC Descriptor and Diagnostic Aids, determine which module is not communicating.

2. Ignition OFF, disconnect the harness connector at the module that is not communicating.

3. Test for less than 0.5 ohm of resistance between each ground circuit of the module that is not communicating and ground.

If greater than 0.5 ohm, repair the open/high resistance in the ground circuit.

4. Test for battery voltage between each battery positive voltage circuit of the module that is not communicating and ground.

If less than battery voltage, repair the short to ground or open/high resistance in the battery positive voltage circuit.

5. Ignition ON, test for battery voltage between each ignition circuit of the module that is not communicating and ground.

If less than battery voltage, repair the short to ground or open/high resistance in the ignition circuit.

6. Ignition OFF, disconnect the harness connector at the module that reported the no communication DTC.

7. Ignition OFF, test for less than 0.5 ohm of resistance in each serial data circuit between the module that is not communicating and the module that reported the DTC.

If greater than 0.5 ohm, repair the open/high resistance in the serial data circuit.

8. If all tests normal, replace the module that is not communicating.

Repair Instructions

Perform the Diagnostic Repair Verification afier completing the diagnostic procedure.

Control Module References for non-communicating module replacement setup and programming.