Circuit Description
Various modules communicate and share information with each other trough the serial data communications system. This reduces the vehicle electrical wiring and provides for the transmission and reception of module signals over a single wire. If a module cannot respond to the powertrain control module (PCM), a diagnostic trouble code (DTC) is stored.
Conditions for Setting the DTC
| • | The PCM cannot communicate with the electronic brake control module (EBCM) or the body control module (BCM). |
| • | During the initial 15 seconds after the ignition switch is turned ON. |
Action Taken When the DTC Sets
| • | The PCM records operating conditions at the time the DTC sets. This information will be stored in the Failure Records buffer. |
| • | A history DTC is stored in the BCM and the PCM. |
Conditions for Clearing the DTC
| • | A history DTC will clear in the PCM after 40 consecutive warm up cycles without a malfunction. |
| • | DTC U1000 clears in the BCM after 100 ignition cycles with no DTCs detected. |
| • | Use the scan tool CLEAR DTCs function. |
Diagnostic Aids
| • | An intermittent problem may be caused by the following conditions: |
| - | Poor electrical connection |
| - | Rubbed through wire insulation |
| - | Broken wire inside the insulation |
| • | Thoroughly test any circuitry that is suspected as causing the intermittent complaint for the following conditions: |
| - | Backed out terminals |
| - | Improper mating |
| - | Broken locks |
| - | Improperly formed |
| - | Damaged terminals |
| - | Poor terminal to wire connection |
If the vehicle has a vehicle theft deterrent system, test for the following conditions for additional aid:
| • | If DTC U1000 and DTC P1632 is set this ignition cycle and the engine stalls immediately after starting. The problem is the same as DTC U1064. Follow the DTC U1064 diagnostic table for further diagnosis. |
| • | If DTC U1000 is set this ignition cycle and the engine continues to run after starting, the problem is the same as DTC U1040. Follow the DTC U1040 diagnostic table for further diagnosis. |
| • | If DTC U1000 is in history only, follow the DTC U1000 diagnostic table. |
Step | Action | Value(s) | Yes | No |
|---|---|---|---|---|
1 | Was the On-Board Diagnostic (OBD) System Check performed? | -- | Go to Step 2 | Go to Powertrain On Board Diagnostic (OBD) System Check 2.4L or Powertrain On Board Diagnostic (OBD) System Check 3.1L |
2 |
Can the scan tool display data from the PCM? | -- | Go to Step 3 | |
3 | Attempt to communicate with the EBCM. Can the scan tool communicate with the EBCM? | -- | Go to Step 4 | Go to Diagnostic System Check |
4 | Attempt to communicate with the body control module (BCM). Can the scan tool communicate with the BCM? | -- | Go to Step 5 | |
5 |
Is the action complete? | -- | Go to Step 6 | -- |
6 |
Does the scan tool indicate that this diagnostic ran and passed? | -- | Go to Step 7 | Go to Step 2 |
7 | Check if any additional DTCs are set. Are any DTCs displayed that have not been diagnosed? | -- | Go to applicable DTC table | Go to Powertrain On Board Diagnostic (OBD) System Check 2.4L or Powertrain On Board Diagnostic (OBD) System Check 3.1L |
