Pinpoint Test U: DTC U1900 - Can Communication Bus Fault - Receive Error (RCM)

WARNING: This page is about a different car, the 2007 Ford Ranger. However, it is still accessible from the selected car via links, so may be relevant.

NOTE: Most faults are due to connector and/or wiring concerns. Carry out a thorough Inspection and Verification before proceeding with the pinpoint test.

U1 CHECK FOR CONTINUOUS AND ON-DEMAND DTCs
WARNING: Restraint system diagnostic tools are for service only. Tools must be removed prior to operating the vehicle over the road. Failure to remove restraint system diagnostic tools could result in injury and possible violation of vehicle safety standards.

WARNING: Never probe the connectors on the air bag module. Doing so can result in air bag deployment, which can result in personal injury.

WARNING: The safety belt pretensioner is a pyrotechnic device. Always wear safety glasses when repairing an air bag equipped vehicle and when handling a safety belt buckle pretensioner or safety belt retractor pretensioner. Never probe a pretensioner electrical connector. Doing so could result in pretensioner or air bag deployment and could result in personal injury.

WARNING: Never probe the electrical connector on a safety canopy module. Doing so can result in safety canopy deployment.

NOTE: The SRS must be fully operational and free of faults before releasing the vehicle to the customer.
- Enter the following diagnostic mode on the diagnostic tool: On-Demand Self Test /Retrieve and Record Continuous Memory DTCs
- Was on-demand DTC U1900 retrieved?
1. YES : This is a hard fault. The fault condition is still present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test. Go to U2 .
2. NO : This is an intermittent fault when present as a continuous memory DTC only (DTC not retrieved on demand). The fault condition is not present at this time. Go to U3 .
U2 CHECK THE HS-CAN NETWORK
- Enter the following diagnostic mode on the diagnostic tool: Carry Out The Data Link Diagnostics
- Did the Data Link Diagnostics test pass?
1. YES : INSTALL a new RCM. REFER to Restraints Control Module (RCM) in this article. Go to U4 .
2. NO : REFER to MODULE COMMUNICATIONS NETWORK article to diagnose the HS-CAN concern. Go to U4 .
U3 CHECK FOR AN INTERMITTENT FAULT
- Key in OFF position.
- Enter the following diagnostic mode on the diagnostic tool: On-Demand Self Test /Retrieve and Record Continuous Memory DTCs
- Was on-demand DTC U1900 retrieved?
1. YES : This is a hard fault. The fault condition is now present. This fault cannot be cleared until it is corrected and the DTC is no longer retrieved during the on-demand self test. Go to U2 .
2. NO : CHECK for causes of the intermittent fault. ATTEMPT to recreate the hard fault by flexing the wire harness and cycling the ignition key frequently. REPAIR any intermittent concerns found. REFER to MODULE COMMUNICATIONS NETWORK article. Go to U4 .
U4 CHECK FOR ADDITIONAL DTCs
- Refer to the continuous memory DTCs recorded during Step U1.
- Were any continuous memory DTCs retrieved during Step U1?
1. YES : Do not clear any DTCs until all DTCs have been resolved. Go to the Restraints Control Module (RCM) Diagnostic Trouble Code (DTC) Table in this article for pinpoint test direction.
2. NO : RECONNECT the system. If previously directed to deactivate the system, REACTIVATE the system. REFER to Supplemental Restraint System (SRS) Deactivation and Reactivation in this article. REPOWER the system. REFER to Supplemental Restraint System (SRS) Depowering and Repowering in this article. PROVE OUT the system. CLEAR all RCM and OCS module DTCs.