Multiplex Communication System: Diagnosis Lexus ES XV30

TROUBLE SHOOTING

1. Trouble shooting of a multiplex communication system complaint begins with verification of the customer problem. If problem occurs, go to step 3 . If problem does not occur, go to next step.
2. If problem does not occur, review conditions under which problem occurred for customer and try to duplicate those conditions. For example, if the problem occurs on rainy days or during high humidity conditions, sprinkle water onto vehicle and see if malfunction occurs. DO NOT sprinkle water directly into engine compartment or onto electronic components. Visually inspect for signs of mechanical and electrical damage. Inspect for blown fuses and damaged relays. Inspect for loose or corroded connections, damaged wiring harnesses and/or switches. Check for a broken or partially broken wire inside insulation, which could cause system malfunction but prove good in a continuity/voltage check with system disconnected. Ensure any aftermarket electronic equipment is properly installed. If fault is found, repair as necessary. If problem still cannot be created, go to next step.
3. Perform pre-check. See «PRE-CHECK»(ref-152050-S38681293452003011300000) under SELF-DIAGNOSTIC SYSTEM. When pre-check confirms diagnostic system is functional, retrieve Diagnostic Trouble Codes (DTCs). See «RETRIEVING DIAGNOSTIC TROUBLE CODES»(ref-152050-S17829536372003012700000) under SELF-DIAGNOSTIC SYSTEM.
4. After problem has been identified and repaired, confirm repairs. See «CONFIRMATION TEST»(ref-152050-S26452632962003012900000) under SELF-DIAGNOSTIC SYSTEM.

RETRIEVING DIAGNOSTIC TROUBLE CODES

Note. Always record DTCs during retrieval.

Note. An OBD II scan tool complying with SAE J1978 can be used if Lexus hand-held tester is not available.

Scheme 1

1. See scan tool operator's manual for specific operating instructions. Connect scan tool to DLC3 located under left side of instrument panel. (Scheme 1) If scan tool cannot communicate with DLC3 diagnostic line when ignition is turned on and scan tool is operated, there is a problem either on the vehicle side or tool side of the link. If communication can be established when scan tool is connected to another vehicle, inspect diagnostic circuit of DLC3 of original vehicle. If communication is still impossible when scan tool is connected to another vehicle, problem is probably in scan tool itself. Consult the Service Department listed in the tool's instruction manual. When communication is established, use scan tool to retrieve DTCs. See tester operator's manual for specific operating instructions. Retrieve and record DTCs. Clear DTCs. See «CLEARING DIAGNOSTIC TROUBLE CODES»(ref-152050-S33734779002003012700000).
2. Operate system for which the complaint was recorded to see if fault can be recreated. If same DTC is displayed and fault is present, problem is current in diagnostic circuit, diagnose and repair DTC. See «DIAGNOSTIC TROUBLE CODE INDEX»(ref-152050-S15495184172003011300000) table. If same DTC is not received and no symptoms are present, original DTC was a history code signifying that problem may have occurred in the wire harness or connector some time in the past or is a secondary problem. Check connectors for loose, damaged or corroded terminals. If same DTC is not received, but fault is still present, problem is still occurring somewhere other than current diagnostic circuit. Diagnose and repair problem based on existing symptoms as follows: For symptoms related to engine performance, see «TROUBLE SHOOTING - NO CODES»(ref-134942) article in ENGINE PERFORMANCE. For symptoms related to door control system, see «POWER DOOR LOCKS, TRUNK LID & FUEL DOOR RELEASE»(ref-151739) article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT, and/or «POWER MIRRORS»(ref-152222) under MIRRORS article in ACCESSORIES & EQUIPMENT. For symptoms related to theft deterrent system, see «ANTI-THEFT SYSTEMS»(ref-152127) article under DOOR LOCKS & ANTI-THEFT SYSTEMS in ACCESSORIES & EQUIPMENT. For symptoms related to power seats, see «POWER SEATS»(ref-152272) under SEATS article in ACCESSORIES & EQUIPMENT.

DIAGNOSTIC TROUBLE CODE INDEX

CLEARING DIAGNOSTIC TROUBLE CODES

To clear DTCs, operate the hand-held tester to erase the codes. See tester operator's manual for specific operating instructions.

CONFIRMATION TEST

After repairs have been completed, confirm that problem has been eliminated. Operate system under same conditions recorded for original complaint. If problem is no longer present and no DTCs are present, repair has corrected problem. If problem is still present or DTCs are reset, further diagnosis and repair is required.

Scheme 2

DTC Detecting Condition

No communication has taken place between driver door ECU and body ECU for more than 10 seconds.

Diagnostic Procedure

1. Turn ignition off. Disconnect body ECU 18-pin harness connector B5, driver door ECU 20-pin harness connector D17 and front passenger door ECU 20-pin harness connector F13. (Scheme 2) Backprobing, check continuity of Gray/Black wire (MPX1 circuit) between body ECU 18-pin harness connector B5 terminal No. 11 and driver door ECU 20-pin harness connector D17 terminal No. 7. Also, check continuity of Gray/Blue wire (MPX2 circuit) between driver door ECU 20-pin harness connector D17 terminal No. 8 and front passenger door ECU 20-pin harness connector F13 terminal No. 8 by backprobing. (Scheme 2)and (Scheme 3). If continuity exists, go to next step. If continuity does not exist, repair identified circuit, harness or connector between body ECU and driver door ECU, or between driver door ECU and front passenger door ECU and retest system. See «COMPUTER DATA LINES»(ref-141318-S06258940582002121100000) under SYSTEM WIRING DIAGRAMS article in ELECTRICAL.
2. With driver door ECU 20-pin harness connector D17 disconnected, check power feed circuits (BDR and CPUB) by backprobing between harness side of connector D17 terminals No. 9 (White/Red wire) and No. 10 (Blue/White wire) and good body ground point. (Scheme 4) If 10-14 volts is present at both test points, go to next step. If 10-14 volts is not present at both test points, repair identified circuit, harness, connector or fuse(s) between driver door ECU and battery. (Scheme 3)
3. With driver door ECU 20-pin harness connector D17 disconnected, check ground circuit ("E") by backprobing between harness side of connector D17 terminal No. 2 (White/Black wire) and good body ground point. (Scheme 5) If continuity does not exist, repair identified circuit, harness or connector between driver door ECU and vehicle ground point located under driver seat. (Scheme 3) If continuity exists, replace driver door ECU. See «DRIVER DOOR ECU & FRONT PASSENGER DOOR ECU»(ref-152050-S01268513802003011400000) under REMOVAL & INSTALLATION.
4. After repairs have been made, perform confirmation test. See «CONFIRMATION TEST»(ref-152050-S26452632962003012900000) under SELF-DIAGNOSTIC SYSTEM.

Scheme 3

Scheme 4

Scheme 5

No communication has taken place between front passenger door ECU and body ECU for more than 10 seconds.

1. Turn ignition off. Disconnect body ECU 18-pin harness connector B5, driver door ECU 20-pin harness connector D17 and front passenger door ECU 20-pin harness connector F13. (Scheme 2) Backprobing, check continuity of Gray/Red wire between body ECU 18-pin harness connector B5 terminal No. 12 (MPX2 circuit) and front passenger door ECU 20-pin harness connector F13 terminal No. 7 (MPX1 circuit). Also, check continuity of Gray/Blue wire (MPX2 circuit) between front passenger door ECU 20-pin harness connector F13 terminal No. 8 and driver door ECU 20-pin harness connector D17 terminal No. 8 by backprobing. (Scheme 2)and (Scheme 6). If continuity exists, go to next step. If continuity does not exist, repair identified circuit, harness or connector between body ECU and front passenger door ECU, or between front passenger door ECU and driver door ECU and retest system. See «COMPUTER DATA LINES»(ref-141318-S06258940582002121100000) in SYSTEM WIRING DIAGRAMS article.
2. With front passenger door ECU 20-pin harness connector F13 disconnected, check power feed circuits (BDR and CPUB) by backprobing between harness side of connector F13 terminals No. 9 (White/Red wire) and No. 10 (Blue/Orange wire) and good body ground point. (Scheme 4) If 10-14 volts is present at both test points, go to next step. If 10-14 volts is not present at both test points, repair identified circuit, harness, connector or fuse(s) between front passenger door ECU and battery. (Scheme 6)
3. With front passenger door ECU 20-pin harness connector F13 disconnected, check ground circuit ("E") by backprobing between harness side of connector F13 terminal No. 2 (White/Black wire) and good body ground point. (Scheme 5) If continuity does not exist, repair identified circuit, harness or connector between front passenger door ECU and vehicle ground point located on instrument panel reinforcement under right side of instrument panel. (Scheme 6) If continuity exists, replace front passenger door ECU. See «DRIVER DOOR ECU & FRONT PASSENGER DOOR ECU»(ref-152050-S01268513802003011400000) under REMOVAL & INSTALLATION.
4. After repairs have been made, perform confirmation test. See «CONFIRMATION TEST»(ref-152050-S26452632962003012900000) under SELF-DIAGNOSTIC SYSTEM.

Scheme 6

DTC B1214 is set when door system communication bus is shorted to battery voltage. DTC B1215 is set when door system communication bus is shorted to ground. If either condition exists, all BEAN communication will cease and some DTCs may be output. (Scheme 7)

1. Turn ignition off. Disconnect driver door ECU 20-pin harness connector D17. (Scheme 2) Turn ignition on and retrieve DTCs. If DTC B1214 or B1215 is present, go to next step. If DTC B1214 or B1215 is not present, replace driver door ECU. See «DRIVER DOOR ECU & FRONT PASSENGER DOOR ECU»(ref-152050-S01268513802003011400000) under REMOVAL & INSTALLATION.
2. Turn ignition off. With driver door ECU 20-pin harness connector D17 disconnected, disconnect front passenger door ECU 20-pin harness connector F13. (Scheme 2) Turn ignition on and retrieve DTCs. If DTC B1214 or B1215 is present, go to next step. If DTC B1214 or B1215 is not present, go to step 4.
3. Turn ignition off. With front passenger door ECU 20-pin harness connector F13 disconnected, reconnect driver door ECU 20-pin harness connector D17. (Scheme 2) Turn ignition on and retrieve DTCs. If DTC B1214 or B1215 is present, replace front passenger door ECU. See «DRIVER DOOR ECU & FRONT PASSENGER DOOR ECU»(ref-152050-S01268513802003011400000) under REMOVAL & INSTALLATION. If DTC B1214 or B1215 is not present, check continuity of multiplex communication circuit (Green/Blue wire) between driver door ECU 20-pin harness connector D17 terminal No. 8 and front passenger door ECU 20-pin harness connector F13 terminal No. 8 to determine if the circuit is shorted to power or shorted to ground. Repair or replace Green/Blue wire between driver door ECU and front passenger door ECU. (Scheme 7)
4. With front passenger door ECU 20-pin harness connector F13 and driver door ECU 20-pin harness connector D17 disconnected, disconnect body ECU 18-pin harness connector B5. (Scheme 2) Check multiplex communication circuit (Green/Black wire) between driver door ECU 20-pin harness connector D17 terminal No. 7 and body ECU 18-pin harness connector B5 terminal No. 11 and (Green/Red wire) between front passenger door ECU 20-pin harness connector F13 terminal No. 7 and body ECU 18-pin harness connector B5 terminal No. 12 to determine if either circuit is shorted to power or shorted to ground. (Scheme 7) If short is identified, repair or replace Green/Black wire between driver door ECU and body ECU or Green/Red wire between front passenger door ECU and body ECU. If circuits are not shorted to power or shorted to ground, replace body ECU. See «BODY ECU»(ref-152050-S21727947152003013100000) under REMOVAL & INSTALLATION.
5. After repairs have been made, perform confirmation test. See «CONFIRMATION TEST»(ref-152050-S26452632962003012900000) under SELF-DIAGNOSTIC SYSTEM.

Scheme 7

DTC B1269 is detected when communication between theft deterrent ECU and body ECU has stopped for more than 10 seconds.

1. Turn ignition off. Disconnect body ECU 18-pin harness connector B5 and theft deterrent ECU 26-pin harness connector T6. (Scheme 2) Backprobing, check continuity of Violet wire between body ECU 18-pin harness connector B5 terminal No. 13 (MPX3 circuit) and theft deterrent ECU 26-pin harness connector T6 terminal No. 10 (MPX1 circuit). (Scheme 2)and (Scheme 8). If continuity exists, go to next step. If continuity does not exist, repair Violet wire, harness or connector between body ECU and theft deterrent ECU and retest system. See «COMPUTER DATA LINES»(ref-141318-S06258940582002121100000) in SYSTEM WIRING DIAGRAMS article.
2. With theft deterrent ECU 26-pin harness connector T6 disconnected, check power feed circuit (+B1) by backprobing between harness side of connector T6 terminal No. 2 (White/Red wire) and good body ground point. (Scheme 9) If 10-14 volts is present, go to next step. If 10-14 volts is not present, repair White/Red wire, harness, connector or fuse(s) between theft deterrent ECU and battery. (Scheme 8)
3. With theft deterrent ECU 26-pin harness connector T6 disconnected, check ground circuit ("E") by backprobing between harness side of connector T6 terminal No. 11 (White/Black wire) and good body ground point. (Scheme 10) If continuity does not exist, repair White/Black wire, harness or connector between theft deterrent ECU and vehicle ground point located on instrument panel reinforcement under left side of instrument panel. (Scheme 8) If continuity exists, replace theft deterrent ECU. See «THEFT DETERRENT ECU (SECURITY ECU)»(ref-152050-S42816413132003011400000) under REMOVAL & INSTALLATION.
4. After repairs have been made, perform confirmation test. See «CONFIRMATION TEST»(ref-152050-S26452632962003012900000) under SELF-DIAGNOSTIC SYSTEM.

Scheme 8

Scheme 9

Scheme 10