Note. Check the PCM for DTCs, and troubleshoot PCM (see GENERAL TROUBLESHOOTING INFORMATION ) or F-CAN loss of communication errors first.
Loss of Communication DTC cross-reference chart
When an ECU is unable to communicate with the other ECUs on the CAN circuit, the other control units will set loss of communication DTCs. Use this chart to find the control unit that is not communicating with the other control units on the CAN circuit.
- Find the Transmitting Control Unit that is in the same row as all of the loss of communication DTCs retrieved.
- Do the input test for the Transmitting Control Unit.
BUS OFF and Internal Error Codes
| DTC type | Related Unit | |||||
|---|---|---|---|---|---|---|
| MICU | Gauge Control Module | Immobilizer-keyless Control Unit | Automatic Lighting Control Unit *1 | HandsFree-Link Control Unit *2 | Climate Control Unit | |
| BUS-OFF | B1000 | B1150 | B1900 | B1550 | U1280 | B1200 |
| ECU (CPU) Error | B1001 | |||||
| ECU (EEPROM) Error | B1002 | B1152 | ||||
BUS OFF AND INTERNAL ERROR CODES REFERENCE CHART
Loss of Communication
| Transmitting Control Unit | Message | Receiving Unit/Loss of Communication DTC | ||||
|---|---|---|---|---|---|---|
| MICU | Gauge Control Module | Immobilizer-Keyless Control Unit | Automatic Lighting Control Unit (1) | Climate Control Unit | ||
| MICU | RM | B1188 | ||||
| HLSW | B1155 | B1555 | ||||
| WIPSW | B1156 | |||||
| MICU | B1157 | B1556 | ||||
| DOORSW | B1159 | |||||
| DRLOCKSW | B1160 | B1905 | ||||
| Gauge Control Module | VSP/NE | B1011 | B1205 | |||
| A/T | B1008 | B1906 | ||||
| ENG TEMP | B1206 | |||||
| PCM | ENG | B1168 | ||||
| A/T | B1169 | |||||
| VSA | VSA | B1170 | ||||
| TPMS | TPMS | B1173 | ||||
| SRS | SRS | B1187 | ||||
| (1) '10-11 models with automatic lighting system *2: '10-11 models with navigation system | ||||||
| (1) | '10-11 models with automatic lighting system |
LOSS OF COMMUNICATION DTC CROSS-REFERENCE CHART
DTC Troubleshooting Index
Note. Check the PCM for DTCs, and troubleshoot PCM (see GENERAL TROUBLESHOOTING INFORMATION ) or F-CAN loss of communication errors first. Next, record, sort, and troubleshoot all DTCs in this order
- Battery voltage DTCs
- Internal error DTCs
- Loss of communication DTCs (beginning with the lowest number first; for example, if DTC B1008 and B1011 are retrieved, troubleshoot DTC B1008 first).
- Signal error DTCs
MICU
| DTC | Description | DTC type |
|---|---|---|
| B1000 | Communication bus line error (BUS-OFF) | Loss of communication |
| B1001 | MICU internal error (CPU error) | Internal error |
| B1002 | MICU internal error (EEPROM error) | Internal error |
| B1008 | MICU lost communication with the gauge control module (A/T message) | Loss of communication |
| B1011 | MICU lost communication with the gauge control module (VSP/NE message) | Loss of communication |
| B1026 | Front passenger's door lock switch signal error (LOCK/UNLOCK) | Signal error |
| B1028 | Rear window wiper motor (As) signal error | Signal error |
| B1032 | MICU lost communication with the SRS unit (CDS message) | Signal error |
| B1036 | IG1 line input error | Signal error |
| B1077 | Windshield wiper (As) signal error | Signal error |
| B1078 | Daytime running lights signal error (Canada) | Signal error |
| B1079 | Daytime running lights signal error (USA) | Signal error |
| B1127 | Driver's door key cylinder switch signal error (LOCK/UNLOCK) | Signal error |
| B1128 | Driver's door lock switch signal error (LOCK/UNLOCK) | Signal error |
| B1129 | Driver's door lock knob switch signal error (LOCK/UNLOCK) | Signal error |
| B1275 | Combination light switch OFF position circuit malfunction | Signal error |
| B1276 | Combination light switch parking light position circuit malfunction | Signal error |
| B1278 | Combination switch ON position circuit malfunction | Signal error |
| B1279 | Headlight switch DIMMER position circuit malfunction | Signal error |
| B1280 | Turn signal switch circuit malfunction | Signal error |
| B1281 | Windshield wiper switch MIST position circuit malfunction | Signal error |
| B1282 | Windshield wiper switch INT (AUTO) position circuit malfunction | Signal error |
| B1283 | Windshield wiper switch LOW position circuit malfunction | Signal error |
| B1284 | Windshield wiper switch HIGH position circuit malfunction | Signal error |
DTC TROUBLESHOOTING INDEX (MICU)
Gauge Control Module
| DTC | Description | DTC type |
|---|---|---|
| B1150 | Communication bus line error (BUS-OFF) | Loss of communication |
| B1152 | Gauge control module internal error (EEPROM error) | Internal error |
| B1155 | Gauge control module lost communication with MICU (HLSW message) | Loss of communication |
| B1156 | Gauge control module lost communication with MICU (WIPSW message) | Loss of communication |
| B1157 | Gauge control module lost communication with MICU (MICU message) | Loss of communication |
| B1159 | Gauge control module lost communication with MICU (DOORSW message) | Loss of communication |
| B1160 | Gauge control module lost communication with MICU (DRLOCKSW message) | Loss of communication |
| B1168 | Gauge control module lost communication with PCM (Engine messages) | Loss of communication |
| B1169 | Gauge control module lost communication with PCM (A/T message) | Loss of communication |
| B1170 | Gauge control module lost communication with the VSA modulator-control unit (VSA message) | Loss of communication |
| B1173 | Gauge control module lost communication with TPMS control unit (TPMS message) | Loss of communication |
| B1175 | Fuel level sensor (Fuel gauge sending unit) circuit open | Signal error |
| B1176 | Fuel level sensor (Fuel gauge sending unit) circuit short | Signal error |
| B1177 | Battery voltage abnormal | Battery voltage |
| B1178 | F-CAN communication line error | Loss of communication |
| B1187 | Gauge control module lost communication with SRS unit (SRS message) | Loss of communication |
| B1188 | Gauge control module lost communication with MICU (RM message) | Loss of communication |
GAUGE CONTROL MODULE DTC TROUBLESHOOTING INDEX
Immobilizer-Keyless Control Unit
| DTC | Description | DTC type |
|---|---|---|
| B1900 | Communication bus line error (BUS-OFF) | Loss of communication |
| B1905 | Immobilizer-keyless control unit lost communication with MICU (DRLOCKSW message) | Loss of communication |
| B1906 | Immobilizer-keyless control unit lost communication with gauge control module (A/T message) | Loss of communication |
IMMOBILIZER-KEYLESS CONTROL UNIT DTC TROUBLESHOOTING INDEX
Climate Control Unit
| DTC | Description | DTC type |
|---|---|---|
| B1200 | Communication bus line error | Loss of communication |
| B1205 | Climate control unit lost communication with gauge control module (VSP/NE message) | Loss of communication |
| B1206 | Climate control unit lost communication with gauge control module (ECT message) | Loss of communication |
| B1220 | A short in the recirculation control motor circuit | Signal error |
| B1225 | An open in the in-car temperature sensor circuit | Signal error |
| B1226 | A short in the in-car temperature sensor circuit | Signal error |
| B1227 | An open in the outside air temperature sensor circuit | Signal error |
| B1228 | A short in the outside air temperature sensor circuit | Signal error |
| B1229 | An open in the sunlight sensor circuit | Signal error |
| B1230 | A short in the sunlight sensor circuit | Signal error |
| B1231 | An open in the evaporator temperature sensor circuit | Signal error |
| B1232 | A short in the evaporator temperature sensor circuit | Signal error |
| B1233 | An open in the driver's air mix control motor circuit | Signal error |
| B1234 | A short in the driver's air mix control motor circuit | Signal error |
| B1235 | A problem in the driver's air mix control linkage, door, or motor circuit | Signal error |
| B1236 | A open in the passenger's air mix control motor circuit | Signal error |
| B1237 | A short in the passenger's air mix control motor circuit | Signal error |
| B1238 | A problem in the passenger's air mix control linkage, door, or motor circuit | Signal error |
| B1239 | An open or short in the mode control motor circuit | Signal error |
| B1240 | A problem in the mode control linkage, doors, or motor circuit | Signal error |
| B1241 | A problem in the blower motor circuit | Signal error |
| B2983 | A problem in the recirculation control motor linkage, door, or motor circuit | Signal error |
| B2986 | An open in the recirculation control motor circuit | Signal error |
CLIMATE CONTROL UNIT DTC TROUBLESHOOTING INDEX
Automatic Lighting Control Unit ('10-11 models with automatic lighting system)
| DTC | Description | DTC type |
|---|---|---|
| B1550 | Communication bus line error (BUS-OFF) | Loss of communication |
| B1555 | Automatic lighting control unit lost communication with the MICU (HLSW message) | Loss of communication |
| B1556 | Automatic lighting control unit lost communication with MICU (MICU message) | Loss of communication |
DTC TROUBLESHOOTING INDEX
HandsFreeLink Control Unit ('10-11 models with navigation system)
| DTC | Description | DTC type |
|---|---|---|
| B1775 | Microphone input/output short to power/open | Signal error |
| B1776 | Microphone input/output short to ground/open | Signal error |
| B1779 | HFL switch or voice control switch (HFL TALK/HFL BACK button) circuit open/short | Signal error |
| B1780 | HFL switch (HFL TALK/HFL BACK buttons) circuit short | Signal error |
| B1792 | HandsFreeLink control unit internal error | Internal Error |
| U1280 | Communication bus line error (BUS-OFF) | Loss of communication |
DTC TROUBLESHOOTING INDEX
Self-diagnostic Function
By connecting the HDS to the data link connector (DLC), the HDS can retrieve the diagnostic information from the MICU via a diagnostic line called the K-LINE. The K-LINE is separate from the CAN line, but it is connected to some of the CAN related ECUs. The MICU is a gateway between the HDS and B-CAN related ECUs, and sends B-CAN diagnostic information to the HDS. When doing a function test with the HDS, the HDS sends an output signal through the K-LINE to the MICU. The MICU either relays the request to another ECU, or commands the function itself.
Scheme 2
Sleep and Wake-up Mode Test
- Shift to the sleep mode: Close all doors. Turn the ignition switch to LOCK (0), and remove the key, then open and close the driver's door. If the MICU receives no further inputs signals, it will go into sleep mode in less than 40 seconds. Driver's door lock switch (LOCK or UNLOCK) Driver's door key cylinder switch (LOCK or UNLOCK) Front passenger's door lock switch (LOCK or UNLOCK) Tailgate latch switch (tailgate closed) (OFF) Tailgate outer handle switch (tailgate open) Hazard warning switch (OFF)
- Confirm the sleep mode: NOTE: Check any official Honda service website for more service information about parasitic draw at the battery. Check the parasitic draw at the battery while shifting into the sleep mode; amperage should change from about 200 mA to less than 35 mA in less than 50 seconds.
- Shift to the wake up mode: When the ignition switch is turned to ON (II), the MICU, and all other B-CAN system components wake up. When any switch in the multiplex integrated control system is turned on, a message is sent to the related control unit(s) to command the desired function. After confirming the sleep mode, look in the following table for the switch most related to the problem. Operate that switch and see if its control unit wakes up. NOTE: If any control unit is faulty and will not wake up, several circuits in the system will malfunction at the same time. In the table below, the control unit is followed by a list of the switches and input signals that can wake it up. Audio-navigation unit or audio unit switch (switch pressed) Door switches (door open) Driver's door lock switch (LOCK or UNLOCK) Driver's door lock knob switch (LOCK or UNLOCK) Driver's door key cylinder switch (LOCK or UNLOCK) Front passenger's door lock switch (LOCK or UNLOCK) Front passenger's door lock knob switch (UNLOCK) Left rear door lock knob switch (UNLOCK) Right rear door lock knob switch (UNLOCK) Tailgate latch switch (tailgate open) Tailgate outer handle switch (tailgate open) Hood switch (with security) (hood open) Hazard warning switch (ON) Combination light switch (parking, headlight, dimmer, passing ON) Ignition key switch (key inserted)
Scheme 3
Scheme 4
Scheme 5
- Clear the DTCs with the HDS.
- Turn the ignition switch to LOCK (0), and then back to ON (II).
- Wait for at least 6 seconds.
- Check for DTCs with the HDS. Is DTC B1000 indicated? YES -Go to step 5. NO -Intermittent failure, the communication bus line is OK at this time. Check for loose or poor connections, or worn/shorted wires. If the connections are good, check the battery condition and the charging system.
- Check for DTCs with the HDS. Are DTCs B1008, B1011, and B1032 also indicated? YES -Go to step 6. NO -Faulty MICU; replace the under-dash fuse/relay box (see «REMOVAL AND INSTALLATION»(ref-371395-S18403628942010091000000) ).
- Turn the ignition switch to LOCK (0).
- Disconnect the appropriate connector at each control unit in the table one at a time. Clear the DTC, then recheck for DTCs after each unit is disconnected. CONNECTOR LIST Unit Connector Gauge control module 36P connector Immobilizer-keyless control unit 7P connector Automatic lighting control unit (if equipped) 14P connector HandsFreeLink control unit (if equipped) 28P connector Climate control unit ('08-10 EX-L models) 36P connector Is DTC B1000 indicated with each individual unit disconnected? YES -Go to step 8. NO -Check the power and grounds to the control unit that was disconnected when DTC B1000 did not reset. If OK, replace the control unit.
- Disconnect all of the appropriate connectors for each of the units in the table. CONNECTOR LIST Unit Connector Gauge control module 36P connector Immobilizer-keyless control unit 7P connector Automatic lighting control unit (if equipped) 14P connector HandsFreeLink control unit (if equipped) 28P connector Climate control unit ('08-10 EX-L models) 36P connector
- Disconnect under-dash fuse/relay box connector Q (16P).
- Check for continuity between under-dash fuse/relay box connector Q (16P) terminal No. 6 and body ground. Is there continuity? YES -Repair a short to ground in the wire between the under-dash fuse/relay box and the affected control unit. NO -Go to step 11.
- Measure the voltage between under-dash fuse/relay box connector Q (16P) terminal No. 6 and body ground. Is there less than 0.2 V? YES -Faulty MICU, replace the under-dash fuse/relay box (see «REMOVAL AND INSTALLATION»(ref-371395-S18403628942010091000000) ). NO -Repair a short to power in the wire between the under-dash fuse/relay box and the affected control unit.
MICU Input Test
Note. Before testing the MICU, troubleshoot the multiplex integrated control unit first using B-CAN System Diagnosis Test Mode A (see TROUBLESHOOTING - B-CAN SYSTEM DIAGNOSIS TEST MODE A ).
Scheme 6
- Turn the ignition switch to LOCK (0).
- Disconnect under-dash fuse/relay box connectors E, F, G, K, R, and T NOTE: All connector views are wire side of female terminals.
- Inspect the connector and socket terminals to be sure they are all making good contact. If the terminals are bent, loose or corroded, repair them as necessary and recheck the system. If the terminals look OK, go to step 4.
- With the connectors still disconnected, do these input tests at the following connectors. If any test indicates a problem, find and correct the cause, then recheck the system. If all the input tests prove OK, go to step 5. MICU INPUT TEST REFERENCE CHART Cavity Wire Test condition Test: Desired result Possible cause if desired result is not obtained G2 ORN Under all conditions Measure the voltage to ground: There should be battery voltage. Blown No. 23 (10 A) fuse in the under-hood fuse/relay box An open or high resistance in the wire K4 PUR Under all conditions (All doors are closed and the ceiling light switch in the door position.) Attach to ground: The ceiling light should come on. Blown No. 22 (7.5 A) fuse in the under-hood fuse/relay box Blown bulb(s) Faulty ceiling light An open or high resistance in the wire R13 RED Under all conditions Attach to ground: The ignition key light should come on. Blown No. 22 (7.5 A) fuse in the under-hood fuse/relay box Faulty LED An open or high resistance in the wire
- Reconnect the connectors to the under-dash fuse/relay box, and do these input tests at the following connectors. If any test indicates a problem, find and correct the cause, then recheck the system. If all the input tests prove OK, the MICU must be faulty; replace the under-dash fuse/relay box (see «REMOVAL AND INSTALLATION»(ref-371395-S18403628942010091000000) ). MICU INPUT TEST REFERENCE CHART Cavity Wire Test condition Test: Desired result Possible cause if desired result is not obtained E6 BLK In all ignition switch positions Measure the voltage to ground: There should be less than 0.2 V. Poor ground (G602) or an open in the ground wire An open or high resistance in the wire E33 BLK In all ignition switch positions Measure the voltage to ground: There should be less than 0.2 V. Poor ground (G602) or an open in the ground wire An open or high resistance in the wire F20 BLK In all ignition switch positions Measure the voltage to ground: There should be less than 0.2 V. Poor ground (G401) or an open in the ground wire An open or high resistance in the wire T34 BLK In all ignition switch positions Measure the voltage to ground: There should be less than 0.2 V. Poor ground (G502) or an open in the ground wire An open or high resistance in the wire