DESCRIPTION & OPERATION
The module communications network provides the ability for module-to-module communication by sharing inputs and outputs instead of each component having an input and output wired directly to each module. Vehicle has 2 module communications networks: the Standard Corporate Protocol (SCP) network and the International Standards Organization (ISO) 9141 network.
The SCP network consists of a pair of twisted wires connected between the Data Link Connector (DLC), Powertrain Control Module (PCM) and instrument cluster. Even if one of the wires is open or shorted, communication is still possible between modules and DLC.
The ISO 9141 network consists of a single wire connected between DLC, Anti-Lock Brake System (ABS) control module, Restraint Control Module (RCM), Central Timer Module (CTM) and Central Security Module (CSM). This article is used to diagnose SCP and ISO 9141 communications network circuit faults. For module locations, see COMPONENT LOCATIONS .
ACCESSING PARAMETER IDENTIFICATION
Turn ignition switch to LOCK position. Connect scan tool to Data Link Connector (DLC). Following scan tool manufacturer's instructions, enter PID/DATA MONITOR AND RECORD for desired module. Operate appropriate system and ensure Parameter Identification (PID) expected values are obtained. See appropriate PID DEFINITIONS table under PARAMETER IDENTIFICATION & DEFINITIONS .
PARAMETER IDENTIFICATION & DEFINITIONS
| PID | Description | Expected Value |
|---|---|---|
| ABSLF_I | Left Front ABS Inlet Valve | (1) |
| ABSLF_O | Left Front ABS Outlet Valve | (1) |
| ABSLR_I | Left Rear ABS Inlet Valve | (1) |
| ABSLR_O | Left Rear ABS Outlet Valve | (1) |
| ABSRF_I | Right Front ABS Inlet Valve | (1) |
| ABSRF_O | Right Front ABS Outlet Valve | (1) |
| ABSRR_I | Right Rear ABS Inlet Valve | (1) |
| ABSRR_O | Right Rear ABS Outlet Valve | (1) |
| BOO | Brake Pedal Position Switch Input | OFF/ON |
| CCNT | No. Of Continuous DTCs | One Bit Per Count |
| LF_WSPD | Left Front Wheel Speed Signal | 0-255 KPH |
| LR_WSPD | Left Rear Wheel Speed Signal | 0-255 KPH |
| RF_WSPD | Right Front Wheel Speed Signal | 0-255 KPH |
| RR_WSPD | Right Rear Wheel Speed Signal | 0-255 KPH |
| PMPSTAT | ABS Pump Motor Status | (1) |
| (1) Expected value should be OFF- - -, OFFO- -, OFF-B-, OFF- - G, OFFO-G, OFFOB-, OFF-BG, OFFOBG, ON- - -, ONO- -, ON-B-, ON- - G, ONO-G, ONOB-, ON-BG or ONOBG. | ||
| (1) | Expected value should be OFF- - -, OFFO- -, OFF-B-, OFF- - G, OFFO-G, OFFOB-, OFF-BG, OFFOBG, ON- - -, ONO- -, ON-B-, ON- - G, ONO-G, ONOB-, ON-BG or ONOBG. |
PID DEFINITIONS (ABS CONTROL MODULE)
| PID | Description | Expected Value |
|---|---|---|
| CCNT | No. Of Continuous DTCs | 0-255 |
| VBAT#1 | System Battery Voltage | 0-25.5 Volts |
| THEFT_T | Anti-Theft Trigger Status | (1) |
| D_DOOR | Driver's Door Ajar | AJAR, CLOSED |
| P_DOOR | Passenger's Door Ajar | AJAR, CLOSED |
| DECKLID | Decklid/Hatch Ajar | AJAR, CLOSED |
| HOOD_SW | Hood Ajar | AJAR, CLOSED |
| UNLKSEL | Unlock Select Line | ON, OFF |
| CTL_LK | Central Lock Switch | ON, OFF |
| CTLUNLK | Central Unlock Switch | ON, OFF |
| DR_LOCK | Door Lock Activated | ON, OFF |
| DR_UNLK | Door Unlock Activated | ON, OFF |
| RADIOSW | Radio Remove Switch | ON, OFF |
| IGN/SS | Ignition Position II | ON, OFF |
| TRUNK_R | Trunk Release Switch Input | ON, OFF |
| SECSPD | Security Speed Signal | ON, OFF |
| SETALRM | Set Alarm Switch | ON, OFF |
| RESETAL | Reset Alarm Switch | ON, OFF |
| TG/HOOD | Tailgate Or Hood ATI | ON, OFF |
| (1) For expected value, see ANTI-THEFT TRIGGER STATUS VALUE DEFINITIONS table. | ||
| (1) | For expected value, see ANTI-THEFT TRIGGER STATUS VALUE DEFINITIONS table. |
PID DEFINITIONS (CSM)
| Scan Tool Value | Definition |
|---|---|
| 02 | Driver's Door Trigger In Unlock State |
| 04 | Other Door Trigger In Unlock State |
| 0A | Driver's Door Trigger In Lock State |
| 0C | Other Door Trigger In Lock State |
| 0F | Ultrasonic Sensing Trigger |
| 10 | Trunk Trigger In Unlock State |
| 18 | Trunk Trigger In Lock State |
| 20 | Hood Trigger In Unlock State |
| 28 | Hood Trigger In Lock State |
| 40 | Radio Trigger In Unlock State |
| 48 | Radio Trigger In Lock State |
| 80 | Ignition Trigger In Unlock State |
| 88 | Ignition Trigger In Lock State |
ANTI-THEFT TRIGGER STATUS VALUE DEFINITIONS
| PID | Description | Expected Value |
|---|---|---|
| CCNT_ICM | No. Of Continuous DTCs | One Count Per Bit |
| OD_CODE_CNT | No. Of DTCs Set Due To Diagnostic Test | One Count Per Bit |
| DTE_SW | Distance To Empty Switch | OFF, ON |
| GAUGESG_EC | Fuel Level Status | NOTOK, OK |
| IGN_R | Ignition Switch - RUN Position | NO, YES |
| IGN_S | Ignition Switch - START Position | NO, YES |
| LIGHTSN | NIGHT (TRUE)/DAY (FALSE) | OFF, ON |
| ODOMETR | Vehicle Odometer - English | No. Of Miles |
| OIL_PSW | Oil Pressure Switch Count | One Count Per Bit |
| RESETSW | Reset Switch | OFF, ON |
| TRIP_SW | Trip Switch | OFF, ON |
| VBAT_EC | System Battery Voltage Potential | NOTOK, OK |
PID DEFINITIONS (INSTRUMENT CLUSTER)
| PID | Description | Expected Value |
|---|---|---|
| ACCESS | Security Access Status | Timed/Coded |
| ANTISCN | Anti-Scan Status | ACTIVE, NOT ACT |
| ENABL_S | Vehicle Starting Status | ENABLED, DISABLED |
| M_KEY | Master Key Present | NO, YES |
| MIN#KEYS | No. Of Key Codes Required To Be Initially Programmed To Start Vehicle | 2-8 |
| NUMKEYS | No. Of Ignition Key Codes Programmed | 0-8 |
| SERV_MOD | Service Module | NO, YES |
| SPARE_KY | Spare Key Programming Allowed | NO, YES |
PID DEFINITIONS (PCM)
| PID | Description | Expected Value |
|---|---|---|
| BRACKET | Bracket Ground Resistance | Less Than 100 Ohms |
| CCNT | No. Of Continuous DTCs | 0-10 |
| D_ABAGR | Driver's Air Bag Module Resistance | 1.7-4.1 Ohms |
| D_ABAG2 | Driver's Side Impact Air Bag Resistance | 1.7-3.2 Ohms |
| D_PRTNR | Driver's Pretensioner Circuit Resistance | 1.7-3.2 Ohms |
| P_ABAGR | Passenger's Air Bag Module Resistance | 1.7-3.2 Ohms |
| P_ABAG2 | Passenger's Side Impact Air Bag Resistance | 1.7-3.2 Ohms |
| P_PRTNR | Passenger's Pretensioner Circuit Resistance | 1.7-3.2 Ohms |
| VBAT | Battery Feed Voltage At RCM | 12-16 Volts |
PID DEFINITIONS (RCM)