BUS +/- Signals Open Or No Response From Central Timer Module
WARNING: This page is about a different car, the 2002 Dodge Dakota. However, it is still accessible from the selected car via links, so may be relevant.
Possible Causes:
- Attempt to communicate with another module.
- Open Ground circuits.
- Open Fused B+ circuits.
- Open PCI Bus circuit.
- CTM.
CAUTION:
Always turn ignition off before disconnecting or connecting any control module connector. Failure to do so could result in damage to control module.
NOTE:
Ensure vehicle being tested has a fully charged battery. If it does not, false symptoms may occur.
NOTE:
For component location, see appropriate illustration under COMPONENT LOCATIONS
. For terminal identification, see appropriate illustration under CONNECTOR IDENTIFICATION
. For circuit and wire color identification, see WIRING DIAGRAMS
. For component removal and installation procedures, see appropriate component under REMOVAL & INSTALLATION
.
Testing:
- Turn ignition off. Connect DRBIII(R) to DLC. Turn ignition on. Using the DRBIII(R), attempt to communicate with the ACM and the CAB. Is the DRBIII(R) able to identify or communicate with the ACM and the CAB? If yes, go to next step. If no, see PCI BUS COMMUNICATION FAILURE .
- Turn ignition off. Disconnect CTM C1 harness connector. Ensure all interior lights are off. Using a 12-volt test light connected to 12 volts, probe CTM C1 harness connector terminals No. 1, 2 and 16. Does the test light illuminate for each circuit? If yes, go to next step. If no, repair open in CTM C1 harness connector Ground circuit(s). Perform BODY VERIFICATION TEST under VERIFICATION TESTS.
- Reconnect CTM C1 harness connector. Disconnect CTM C3 harness connector. Turn ignition on. Using 12-volt test light connected to ground, probe CTM C3 harness connector terminals No. 1 and 6. Does the test light illuminate for each circuit? If yes, go to next step. If no, check PDC fuses No. 3 and 12 for an open. If fuses are okay, repair open in CTM C3 harness connector Fused B+ circuit(s). Perform BODY VERIFICATION TEST under VERIFICATION TESTS.
- Turn ignition off. Reconnect CTM C3 harness connector. Disconnect CTM C1 harness connector. Connect Scope Input Cable (CH7058) to channel one connector on DRBIII(R). Connect Cable-To-Probe Adapter (CH7062) and Black and Red test probes to scope input cable. Using the DRBIII(R), select PEP MODULE TOOLS, LAB SCOPE, LIVE DATA and 12 VOLT SQUARE WAVE. Press F2 for SCOPE. Press F2 and use DOWN arrow to set voltage scale to 20 volts. Set probe to x10. Press F2 again when complete. Connect Black test probe to ground. Connect Red test probe to CTM C1 harness connector terminal No. 10. Turn ignition on. Observe DRBIII(R) lab scope. Does voltage toggle from zero to approximately 7.5 volts? See Fig 1 -Fig 3 . If yes, go to next step. If no, repair open in PCI Bus circuit. Perform BODY VERIFICATION TEST under VERIFICATION TESTS.
- If there are no possible causes remaining, replace CTM. Perform BODY VERIFICATION TEST under VERIFICATION TESTS.
NOTE:
Ensure there is PCI Bus communication with other modules on the vehicle before proceeding. If not, see PCI BUS COMMUNICATION FAILURE
.