DTC P1698: No Bus Message From Trans Control Module: Testing
- Turn ignition on, with engine off. Using scan tool, check for DTCs. If DTC SPECIFIC GOOD TRIP counter is displayed and displayed count is "0", go to next step. If DTC SPECIFIC GOOD TRIP counter is not displayed or displayed count is not "0", go to step 6 .
- Ensure ignition is on. Using scan tool, select ENGINE MODULE. Using scan tool, check for DTCs. If DTC is also set for NO SKIM BUS MESSAGE and/or NO MIC BUS MESSAGE, go to next step. If DTC is not also set for NO SKIM BUS MESSAGE and/or NO MIC BUS MESSAGE, go to NO RESPONSE FROM TCM under SYSTEM TESTS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
- Using scan tool, select the following control modules and note if they communicate with scan tool. Using scan tool, select BODY then BCM. Using scan tool, select DOOR MODULES. Using scan tool, select ANTI-LOCK BRAKES. Using scan tool, select ELECTRO-MECHANICAL CLUSTER (MIC). Using scan tool, select PASSIVE RESTRAINTS then AIR BAG. If one or more modules communicated with scan tool, go to next step. If no modules communicated with scan tool, go to PCI BUS COMMUNICATION FAILURE under COMMUNICATIONS in BODY CONTROL MODULES - GRAND CHEROKEE article in ACCESSORIES & EQUIPMENT.
- Turn ignition off. Disconnect PCM connectors. PCM is located on firewall in right rear corner of engine compartment. Visually inspect connectors for corroded, damaged, pushed-out or miswired terminals. Repair connectors as necessary. If connectors are okay, ensure scan tool is connected to Data Link Connector (DLC). Connect Scope Input Cable (CH7058) to channel one connector on scan tool. Obtain Red and Black test probes from DRB scan tool test kit. Connect Red and Black test probe leads to Probe Adapter (CH7062). Connect probe adapter to scope input cable. Using scan tool, select DRB STANDALONE, LAB SCOPE, LIVE, then 12 VOLT SQUARE WAVE. Using scan tool, press F2 for scope. Press F2 again and arrow down until 20 volt scale is selected. Press F2 again when complete. Connect Black test probe to ground and Red test probe to terminal No. 30 (Yellow/Violet wire) at PCM C3 connector. See Figure . Turn ignition on and observe voltage displayed on DRB lab scope. If voltage pulses from zero volts to about 7.5 volts, go to next step. If voltage is a constant zero volts, repair open PCI bus circuit (Yellow/Violet wire). See WIRING DIAGRAMS article.
- PCM has an internal open PCI bus circuit. Replace PCM.
- Turn ignition off. Visually inspect related connectors and wiring harness for damage. Repair connectors and wiring harness as necessary. If connectors and wiring harness are okay, no problem is indicated at this time. Check for any related technical service bulletins that may apply.